wegemt workshop...incat 74 metre wave piercing catamarans from tasmania in 1990. the industry then...

Book Ref. GG96001

WEGEMT WORKSHOP

Friday, 13 September, 1996

venueUniversity of Glasgow

hosted byDepartment of Ship & Marine Technology,

University of Strathclyde,

and Department of Naval Architecture,U University of Glasgow,

WEGE.\IT Worksholp on

Conceptual Designs Of Fast SeaTransportation

Proceedings of a one-day Workshop held onFriday 13 September 1996

James Watt Building, University of Glasgow

Hosted by the Universities of Strathclyde and GlasgowSCOTLAND

Published by WEGEMT

Publication reference number GG96001

ABOUT VT G ENIG TWEGEMT isa European Association of37 universities in 17 countries. It was formedin 1978 with die aim of increasing the knowledge base. and updating and extending theskills and competence of engineers and postg-aduate students working at an advancedlevel in marine technology and related science.

WEGEMT achieves this aim by encouraging universities to be associated with theFoundation. to operate as a network and therefore actively collaborate in initiativesrelevant to this aiim

WEGEMT considers collaborative research, education and training activities at anadvanced level. and the exchange and dissemination of information, as activities whichfurther the aim of the Association.

NB For "marine technology and related science", this includes all aspects ofoffshore oil & gas exploration and production, shipping and shipbuildin&underwater technologies and other interdisciplinary areas concerned with theoceans and seas.

ABOUT THE PUBLICATION

This publication represents a series of lecturers' notes which were presented at a one-day Workshop on Conceptual Designs of Fast Sea Transportation first presented atthe University of Glasgow on Friday 13 September 1996.

ISB.N - 1 900453 02 9

Published by WEGEMT

Copyright © 1997 WEGEMT. All Rights Reseived. No part of this publication maybe reproduced- stored in a retrieval system or distributed in any form or by any mean:without the prior ,ritten consent of the publisher.

This volume has been made available so that it contains the original authors't'pesciipts. Thie method may from time to time display typographical limitations. It ishoped however, that they do not distract the attentions of the reader. Please note thatdie views expressed are those of the individual author(s) and the publishers cannotaccept responsibility for any errors or omissions.

WEGEMT Workshop on

Conceptual Designs Of Fast Sea Transportation

Friday 13 September 1996

James Watt Building. University of Glasgow

Hosted by the Universities of Strathclyde and GlasgowSCOTLAND

CONTENTS

Review of Recent Developments in Fast Sea Transportation and Future PotentialMr Stephen Philips, Seaspeed technology Ltd., UK.

The Euro-Express Concept-Application of Slender Monohull Design to Fast VesselsMr Kai Levander. Kvaerner-Masa Yards, Finland.

The Techno-Superliner ConceptDr Kazuo Sugai. japanese Shipbuilding Research Association, Japan.

SES ConceptsMr Geir T Rise. Lund Moluo & Gaiever, Norway.

The Commercial Requirement for a New Shipping InitiativeMr Geoffiey Phillips. Thorneycroft Giles and Co Inc, UK.

New Concept Hull Forms for Fast Sea TransportationM S Shin. S I Yang. E C Kim. KRISO, South Korea.

Developments and Potential in Open Sea SWATH ConceptsProfessor Apostolos Papanikolaou. NTUA. Greece.

REVIEW OF RECENT DEVELOPMENTS IN FAST SEATRANSPORTATION AND FUTURE POTENTIAL

byMr. Stephen Phillips, DirectorSeaspeed Technology Ltd., UK

Paper presented at theWEGEMT Workshop on

Conceptual Designs Of Fast Sea TransportationFriday 13 September 1996

Universities of Strathclyde and GlasgowSCOTLAND

CONCEPTUAL DESIGNS OF FAST SEA

TRANSPORTATION

WEGEMT WORKSHOP - 13TH SEPTEMBER 1996

GLASGOW - SCOTLAND

FAST SEA TRANSPORTATION - A REVIEW OF RECENT

DEVELOPMENTS AND FUTURE POTENTIAL

BY S.J.PHILLIPS BSc CEng FRINA

Director, Seaspeed Technology Limited

1. Introduction

The fast marine transport industry has grown substantially over the past twenty fiveyears, approximately doubling in size every five year period.

Up until 1990 this industry consisted entirely of passenger carrying craft - with theexception of a small number of large hovercraft able to carry passengers and cars.Since 1990 the growth in fast ferries carrying passengers and cars has been very rapidwith over 30 such vessels in service by mid 1996.

This rate of growth (see Figure 1.) has caught the interest of designers and shipbuildersworldwide and, combined with the innovative technology associated with the design ofthese craft, is providing a catalyst for a much needed change in traditional navalarchitecture and shipbuilding.

The industry started with small boatbuilders, mainly in the UK, Scandanavia andAustralia. building relatively small but fast craft. This progressed, particularly inAustralia. to these same builders building larger and larger craft until the arrival of theInCat 74 metre wave piercing catamarans from Tasmania in 1990. The industry thenexpanded very quickly with a large number of traditional European shipbuildersproducing still larger craft, with the largest to date being the Stena HSS 1500, which isa 120 metre catamaran craft with the ability to carry 1620 passengers and 375 cars atspeeds up to 40 knots.

The technology, regulations and commercial considerations which have developed inassociation with these craft are leading to a changed culture in the shipbuilding industryworldwide. The benefits are that rationality is replacing tradition. This is clearly ahealthy situation for an industry so long as the fundamental reasons for the traditionalapproach are understood. Unfortunately many of these reasons have become lost intime and so close attention to safety is now even more critical to the continuingsuccessful development of the industry.

This cultural change is being fuelled by a similar expansion of the cruise ship industryand a cross fertilisation of ideas from other advanced transport sectors. A-s a result, theapplication of fast sea transport technology is being investigated in more depth leadingnaturally to the possibility of transporting freight at higher speeds and over longerdistances at sea.

2. Benefits of Speed

The most fundamental benefit that speed can offer is the reduction in capitalexpenditure and in some.fixed running costs. This is explained very simply for the fastferry industry where, for example, a vessel which can operate at 40 knots carrying say500 passengers could be used in place of a more traditional vessel operating at 20 knotscarrying 1000 passengers. They both have the same transport capacity over a givenperiod of time and yet the faster vessel will be considerably smaller, will have asubstantially lower capital cost and will require less crew to operate it. The fastervessel will almost certainly have a higher fuel requirement and the economics of oneoperation over the other will vary as the price of fuel, wages and other items fluctuate.At present, ship operators clearly find the economics of the faster vessels moreattractive although this is not to say that they will remain so.

There are however other commercial advantages that have been found in practice toaccrue from the faster craft, some of which are:

- The ability to serve a niche market for those wishing to get from A to B in asshort a period of time as possible.

- The opening up of new routes that would otherwise be considered unworkabledue to the time involved if serviced by conventional craft.

- The flexibility within one craft to operate economically at low, medium andhigh speed to suit variations in payload demand, thus mini'mising capital investment fora given demand profile.

-The ability to complement existing operations, meeting peak demands orvariations in light freight to passenger ratios in a cost efficient manner.

- The ability to substantially reduce crewing costs in instances where the crewon conventional craft would otherwise have to work in shifts and/or be accommodatedaway from their home port.

- The ability in a growing number of instances to take on the passenger andsmall vehicle carrying capacity of conventional vessels, allowing a more cost effectiveoperation. The truck and more dense cargo capacity of these conventional craft beingcarried by other dedicated vessels.

Interestingly, it is not only strictly the speed of these vessels which offer benefits: thepresent regulations governing themt also offer opportunities. These regulations take intoaccount both the design and operation of the craft with the emphasis on operationsrather than prescriptive design. This has provided significant opportunities to produceless expensive and more efficient vessels albeit with some operational restrictions. It ishoped, however, that this will be a short lived advantage since it is likely thatconventional ship regulations will in the future also become more rational and followthis trend.

3. Existing Craft Types

3.1. .Achievement of High Speed

In order to achieve higher ship speeds it is clearly necessary to increase the propulsivethrust available and./or to reduce the thrust required to propel the craft at sea. Whilstthe increase in thrust available is largely reliant on the propulsive power installed andadvances in prime mover and propulsor design, the reduction in thrust required in calmand rough water is primarily a function of the craft's hydrodynamic and to a lesserextent aerodynamic design. It is these latter issues which have lead to the diversity offast marine craf .t types discussed in this section and to their light weight construction.

The two principal means of reducing hydrodynamic drag that have been used to dateinclude:

a. Inducing substantial hydrodynamic and/or aerodynamic lift on the craft such that itclears the water surface, either partially (in the case of planing craft, hydrofoils andsome SES) or completely (in the case of some hovercraft and Wing-in-ground-effectcraft).

b. Shaping a displacement hull form such that the hydrodynamic pressure and/orviscous drag components are minimised. The high length to displacement hull form is agood example of this and has been exploited in slender monohull and many multihulldesigns.

3.2. Monohulls

Potentially the simplest of all the hull form concepts, the monohull generally offers alow cost and low risk solution. The drag of a monohull is reduced by either designing aplaning hull form which generates significant lift thus reducing the amount of hull inthe water or by designing the hull to have a very high length to displacement ratio inorder to minimise hydrodynamic pressure (wave) drag. Clearly if the latter is taken toan extreme and the hull is made too long then the frictional drag component willincrease so as to offset the low wave drag characteristics.

It is interesting to note that the term 'Slenderness Ratio' which refers to the length todisplacement ratio is easily misinterpreted as meaning length to beam ratio. Whilstlength to beam ratio generally increases with length to displacement ratio, it should benoted that it is the latter which has the dominant effect on resistance, not the former.Increased beam has for many years been incorrectly accepted as being detrimental toresistance in the case of semi-displacement craft. This is not strictly so and it is quitepossible to have two fast vessels of the same length and displacement with one having amuch broader beam than the other and for them both to have similar resistancecharacteristics (see Figure 2.).

There is however a limit to how much the beam can be increased for a given lengthand displacement since the vessel's block coefficient can quickly become impracticallysmall. Thus the static stability of slender monohulls can be an important limiting factorin the design and can present significant safety problems particularly for vesselsrequiring large unsubdivided decks low down in the hull.

3.3. Multihulls

The multihull configuration can clearly overcome the stability problems of slendermonohulls whilst benefiting from their low drag characteristics and this is one of theincentives for designing with more than one hull.

Other equally important benefits are the ease of providing efficient deck layouts,particularly for ferry operations, and the provision of multiple independent propulsionsystems and a potentially low capsize vulnerability, both due to the multiple hulls.

There have been a number of investigations made into the effect of hull numbers andhull positions on the overall powering and seakeeping performance of a multihull. Todate the catamaran is by far the most common configuration although trimarans andquadramarans have also been constructed. The simple catamaran clearly offers all themajor advantages of a multihull but it is the trimaran which is probably the mostflexible arrangement in meeting a variety of needs. This is because the side hulls caneither be made very short and used to stabilize a long narrow (monohull) centre hull forgood powering and seakeeping performance or they can be made the same length asthe centre hull to offer good powering performance for vessels of restricted length. Theside hulls can also be positioned longitudinally to suit the layout requirements. Asimplified comparison of the resistance of a monohull, catamaran and trimaran all of

the same displacement and speed, is presented in Figure 3. This figure is based ofl allthree hulls of the trimaran being the same length although the monohull line could alsobe assumed to represent the case of a trimaran with very small side hulls.

3.4. Hydrofoils

Another means of reducing resistance and improving seakeeping of a fast vessel is tolift the main hull clear of the water surface. In the case of a hydrofoil this is achievedby a series of underwater lifting surfaces (foils) which generate the requiredhydrodynamic lift. Whilst this presents a challenge for the design of the hull and foilstructure, the means by which the vessel retains longitudinal and transverse stabilitybecomes a critical design factor. There are three main foil arrangements which haveproven successful to date all of which are generally arranged transversely with a singleforward foil and one or two aft foils:

a. The surface piercing foil

Here the outer extremities of the transverse foils are designed to extend at a divergentangle through the water surface such that with an imposed angle of heel, the lift on thefoil on the downward side is increased and conversely reduced on the upward side,thus providing a stabilizing moment. Likewise with an imposed angle of trim, the foilsat the forward end and aft end gain and loose lift in such a manner as to provide alongitudinal restoring moment.

This arrangement is probably the most simple, is certainly the most common but ofcourse also suffers from a significant variation in lift generation when travellingthrough waves, thus inducing heave, pitch and roll motion.

b. The fully submerged roil

Here the lift generating foils are fully submerged to significantly reduce the liftvariation imposed by waves. However, with no surface penetration of the liftingsurfaces, this configuration is unstable in pitch, roll and heave. In order to provide therequired stability the lift on the foils needs to be automatically controlled. This isnormally achieved by mechanically varying the angle of incidence of the lifting surfaceand controlled by feedback from a motion sensor.

This type of arrangement has been very sucessfully used, particularly in the BoeingJetfoil craft, to produce a vessel capable of operating comfortably at very high speedsover rough water. Their limitations are imposed by a practical limit to the length(depth) of foil than can be accommodated but more importantly by the limiting seaconditions that allow the vessel to accelerate from rest in the hull borne mode to theoperating foil borne mode.

c. The surface following foil

This arrangement was developed in Russia by the late Dr Alexeyev and is the mostcommon arrangement for the numerous hydrofoils operating on the Russian riversystem. The lifting foils in this case are fully submerged but only just below the watersurface. Stability is gained by the fact that foils exhibit a reduction in lift as they arebrought nearer to the water surface. If the submergence of a foil in operation isincreased by the effect of roll, pitch or heave then the lift will increase thus providing arestoring force. Likewise if its submergence is decreased then lift is lost, againproviding a restoring force. Whilst this arrangement offers a simple, lightweight andlow drag system, the performance in rough water can be unsatisfactory for operation inexposed sea conditions.

3.5. Air Cushion Vehicles

Another method of lifting a hull clear of the water is with the use of a cushion ofpressurised air. In the case of the hovercraft, which contains the air cushion within acircumferential flexible skint, this has the advantage of making the vessel amphibiousand in practice this has proven to be its most important benefit. The other benefit ofcourse is the very ]ow thrust requirement for achieving high speed although this isslightly offset by the reliance on air rather that water as the propulsive medium, thisbeing most noticeably a problem in strong head winds!

In order to offer the benefits of water propulsors and reduced maintenance costs for thevulnerable skirt system, the concept of a sidewall hovercraft was introduced. In thiscase the side skints are replaced by long slender rigid hulls or 'fences' which limit thepressurised air leakage to the remaining forward and aft skirts or 'seals'. This ofcourse is no longer amphibious but it does retain the very low power requirements forhigh transit speeds. The sidewall concept is now well developed and resembles an aircushion supported catamaran. These craft are currently referred to as surface effectships (SES). They offer most of the benefits of a catamaran configuration with theadditional advantage of very low propulsive thrust requirements. However the vesselsoverall system engineering is less straightforward and the construction of the flexibleskirt system has proven vulnerable in many operations, imposing additionalmaintenance effort.

3.6. SWATH Crart

Although often referred in discussions on fast craft, this concept does not readily lenditself to particularly high speeds. It does however have significant seakeeping benefitsover just about any other marine vehicle and an associated ability to maintain speed inrough conditions.

The concept is based on a twin hull configuration, each hull consisting of submergedlower (torpedo like) hull with a slender strut attached to its upper surface, whichextends through the water surface and joins the upper cross structure forming acatamaran like arrangement. The hull is supported at all speeds by the buoyancy of thelower hulls with the side struts providing transverse and longitudinal stability. the sidestruts are often designed to become wider from some point just above the waterline,forming a more buoyant structure known as a 'haunch'. This provides the staticstability and reserve buoyancy needed to satisfy the current stability requirements.

In waves, the narrow side hulls ensure that only small buoyancy force variations areexperienced by the vessel thus minimising ship motions. The ratio of the vessel'sdisplacement to its waterplane area can be varied, as can the shape of the waterplaneitself, to provide minimum ship motion in given sea state and speed combinations.

The disadvantages of existing fast Swath configurations are in general a deep draft,higher power requirements for a given calm water speed and the difficulty in arrangingpropulsion machinery (due to the narrow side struts). The advantage is the high level ofpassenger comfort offered and the ability to maintain speed in rough conditionscompared to virtually any other alternatives.

3.7. Wing-In-Ground-Effect Craft (WIG's)

Another example of Russian ingenuity, the WIG or Ekranoplan as it is called inRussia, is a very low flying aircraft w~hich generates lift more efficiency by operatingin ground-effect only a few metres above the sea surface. These craft can currentlytravel at speeds of up to 300 knots. In the case of the Ekranoplan, turbofan propulsorsblow over and under the wings thus providing significant lift even at very low craftspeeds. Their fuselage, or main hulls, are generally reinforced on their underside andthey can take off from land (flat ground, ice or snow) or sea over a very short distanceand are substantially amphibious.

Maintaining dynamic stability has proven to be a technological challenge during theirdevelopment although this is understood to have been largely Solved. However theoperation of such craft at these very high speeds very close to the sea surface inevitablyraises the question of operational safety. The regulators for such craft have yet to beidentified!

4. Technical Developments in Fast Marine Transportation

The main technical developments in this industry currently fall into about sixcategories:

- Improved hull form arrangements- Active motion control- Lightweight materials and structures- Propulsion systems- Marine escape systems- Docking and loading facilities

a. Improved hull form arrangements

Whilst the vessel types described in Section 3. above represent the main concepts thathave been tnied and tested to date, there have been many successful (and unsuccessful)combinations of these concepts. The most successful include:

i. The semi-swath catamaran. This hull form incorporates a swath like bow and midbody, for improved seakeeping ability, with a more conventional stem shape, allowingfor a practical and efficient propulsion system layout. This arrangement is emerging inEurope as the most promising hull forms for the larger multihull fast ferries.

ii. The hydrofoil supported catamaran. This is a catamaran which is either partially ortotally supported by hydrofoils in order to reduce resistance. A number of successfulcraft have been developed using this concept although, to date, the foil technology hasrestricted the practical size of the craft.

iii. The air-lubricated (air cushion) mono and multi hull. This is a craft which has anair cushion cavity built into the lower hull which is supplied with pressurised air. Thisprovides a certain degree of lift to the vessel but more importantly can significantlyreduce the wetted area of the hull. The need for flexible skint systems on these crafttypes is generally avoided. This is an area of rapid development at, present withshipyards in Australia and the USA building craft with air-lubricated hulls.

b. Active motion control

These are systems which are designed to actively control the motion of the vessel.Whilst passive damping can be effective in reducing resonant motions, activestabilisation (ride control) has been found to offer substantial benefits in terms ofpassenger comfort.

In most fast craft the ride control system consists of a series of underwater fins,actively controlled to provide variable lift forces aimed at minimising the ship motion.The systems vary in complexity, some minimizing pitch, roll and heave (as on someSwath craft) whilst others aim to minimize vertical accelerations at specific points onthe vessel. The fins are generally hydraulically activated although a electric activationis also currently being pioneered in the USA. It should be noted that these active finsystems generally have a much higher frequency of activation than conventional rollstabilizers since the pitch periods experienced by vessels operating at high speed aregenerally much shorter than their roll periods. Some vessels make use of activetransom flaps to provide the lift control at the aft end of the vessel. This system offers

minimum additional drag although is less efficient since significant downward forcesare more difficult to generate.

In air cushion craft the ride control system can include an actively controlled vent inthe air cushion boundary which controls the craft motion by varying the pressure in theair cushion. Varying the supply fan flow rate has also been investigated but was foundin practice to be more costly.

Whilst ride control systems can provide significant motion reduction in low to moderatesea states, the effectiveness of these systems reduces with increasing wave period andhence loose their usefulness in higher wave conditions.

c. Lightweight materials and structures

The speed of any fast vessel will be improved by reducing its weight and consequentlygreat effort is being made to provide light weight hull structures, equipment and outfitmaterials. Aluminium has become almost universal for the hull and superstructureconstruction of fast ferries and it is difficult to see the use of steel or compositematerials making an impact in the larger craft. All else being equal, the use of steel forthe hull construction generally results in a lower payload capacity and/or lower speedand the financial penalty in the use of composites again makes it uneconomical.However the combination of materials, used in the particular areas of the vessel wherethey can contribute distinct benefits is becoming more common. For example a steelcross structure for a large multihull may provide the stiffness required without anysignificant weight penalty. The use of composites in non load bearing areas can alsoprovide significant weight savings without cost penalties. In the selection of materials itis clearly important to see the effect that the choice has on the overall operation ratherthan just the local technical issues.

d. Propulsion systems

With the development of the larger craft, propulsion systems capable of absorbingbetween 25MW to 60MW are being developed for ship speeds of 40 knots and above.At present this is mainly centred on the development of large wacerjets with internalimpellers. It is difficult to see that open propellers will be developed for theseapplications except perhaps for very large SWATH craft.

For the long term, waterjets designed without conventional impellers are beinginvestigated. These may use fuel injected directly into a waterjet with combustiontaking place within the jet itself.

e. Marine escape systems

Rightly or wrongly, the emphasis of the rules under which fast craft are regulated is on'evacuation' of the vessel in emergency conditions rather than 'damage control'.Therefore there is clearly a requirement to improve the speed and quality of passengerevacuation over traditionial methods.

This has lead to an acceleration in the development of a number of marine escapesystems (MES) in which passengers can escape from the ship into liferafts withoutentering the water. The most significant developments have been in the modificationinflatable slide systems such that passengers not only transfer from the ship. down theslide and directly into the liferafts but also do so in a system which keeps the liferaftsseparated from the ship side. This is important since, ini rough sea conditions, the areaimmediately around the ship can be extremely dangerous. The escape rates on some ofthese systems has also been improved dramatically with a recent deployment of a twintrack slide recording 424 passengers evacuated in 8 minutes 15 seconds.

Other important developments have been in what are known as vertical descentsystems where passengers transfer from the ship via a vertical chute into the liferafts.

The chute is designed to ensure a safe rate of descent and this aspect has beenapproached in various ways by the different manufacturers. The advantage of such asystem is that the height of deployment is not a restriction whereas for inflatable slidesthe current practical restriction in height is about 15 metres due to the difficulties inproducing an inflatable slide of sufficient strength and stiffness.

f. Docking and loading systems

Whilst the higher speeds of these craft at sea can offer reduced crossing times, theimportance of the reduction in 'block time' (ie the time from leaving one port toleaving the next) should be recognized. Indeed a reduction in the time that the craftspends loading and unloading passengers and cargo is possibly more important toaddress since it is by far the cheaper way of reducing 'block time' when compared tothe increased cost of the fuel required for higher ship speeds.

New docking arrangements have been designed for many of the most recent high speedferries in an attempt to reduce the time in port. In particular the Stena HSS operationsuse an automated docking system for the ship which takes over control the vessel onceclose to the docking area and manoeuvres the ship into position. The passengers arethen provided with a dedicated passageway into the shoreside terminal and the vehiclesprovided with a number of routes out of the stem of the craft.

With the development of fast freight craft it will also be vital to have a well developedrapid loading/unloading system to ensure that block times are kept to a minimum. Anumber of different systems are under development at present for existing freightvessels but the new faster, smaller freighters will provide an additional opportunity tooptimize the ship and shore facilities, particularly since the fast freighters are likely tobe of a very different arrangement to existing craft.

5. Potential for Fast Vessels in the Existing Freight Market

The success of fast vessels in the freight market will clearly rely on their ability togenerate a better overall commercial return than by using existing conventional craft.

Since the economics of freight operations depend heavily on so many parameters,many of which vary with time, it would be difficult to come to any reliable conclusionin this forum. However it is worth looking to see whether the size and performance ofexisting vessels can provide an indication of what is likely to be feasible in the nearfuture.

A study of the merchant fleets of the world was recently made by the US MaritimeAdministration (Ref 1). The numbers of merchant ships, divided into their relevantfunctional groups, is presented in Figure 4.

It can be seen that approximately half the numbers of ships in the world fleet are usedin the bulk and tanker trade and since the average deadweight of these ships is so high(Figure 5.) they are clearly not candidates for fast ship technology.

However the remaining groups (passenger and cargo, general cargo, container and ro-ro) all have potential sub-groups for which this technology could be relevant. Lookingat the size of the vessels in the passe nge r/cargo, general cargo and ro-ro groups(Figure 5.) the average deadweight capacity is below 10,000 tonnes.

Another survey of conventional ro-ro craft building in 1996 (Ref 2) also reveals that themajority of these vessels have deadweight capacities below 10,000 tonnes (see Figure6). Additionally, it is interesting to note that 95% of these ro-ro craft have speeds ofbelow 25 knots, and the majority of these are below 20 knots (see Figure 7.).

By analysing the capability of current fast ferries it is not difficult to see that byreplacing the passenger/vehicle and associated outfit weights with freight areas, thefreight capacity of these already proven 40 knot vessels could be well over 500 tonnes.

Thus it is evident that in terms of size there is potential in terms of current or 'close'technology to provide fast freight vessels of the same net freight transfer capacity tocurrent conventional freight vessels in the same manner as has been done for fastferries (le provide fast vessels of half the carrying capacity but twice the speed whencompared to existing craft, where the capital cost of the fast craft is substantially lessthan that of the conventional vessel).

Since so many freight craft, almost by the nature of their function, operateinternationally and many in exposed sea conditions, it is important to investigate theexpected performance o~f these vessels in the relevant sea conditions.

The sea state statistics for a number of sea areas relevant to international freightoperations is presented in Figure 8. For year round service it is required that thevessels be capable of operating with a high degree of availability at the service speed,certainly with the ability to maintain high speed for over 95% of the time.

By plotting the sea state statistics on a logarithmic scale it is possible to see that for seaareas such as the Caribbean and Mediterranean the fast vessels must be able to operateup to at least a significant wave height of 4 metres to give an availability of 95%.

For more exposed areas such as the North Sea, East China Sea and South China Seathe vessels should be able to operate at high speed up to significant wave heights of 6metres for an availability of 98% and for trans-ocean service, a significant wave heightof 8 metres for a similar level of availability.

Thus current fast vessel technology could be used to provide the performance requiredfor Caribbean and Mediterranean routes although it is clear that on more exposedroutes a significant reduction in availability would be expected for these craft.

Using motion data for conventional fast catamarans at 40 knots, the LCG verticalacceleration was calculated for a range ship sizes and sea states and the results plottedin Figure 9. This figure indicates the limiting significant wave height at which certainacceleration thresholds are met.

On a very crude assumption that the acceleration at the most forward freight Positioncould be 1.5 times the LCG acceleration and knowing that the peak acceleration isapproximately equal to 4 times the rins value, then to avoid a peak accelerationexceeding ig (for freight safety), the limiting LCG rms acceleration should be about1.5 m/s^2.

For a conventional catamaran operating in the Caribbean/Mediterranean sea areas thisequates to a vessel of approximately 125 metres which may have a freight deadweightcapacity of about 1200 tonnes (assuming a deadweight to displacement ratio ofapproximately 0.3 for this size of vessel). It is expected that this would be the smallestfast freight vessel that could be seriously proposed for practical operation in exposedsea conditions.

For open sea operation the vessels are likely to be considerably larger with currentproposals ranging from 5000 tonnes to 30,000 displacement giving freight deadweightvalues of 1500 to 10.000 tonnes respectively.

6. The Future of Fast Sea Transportation

Analysing the current trends in fast marine craft orders (Ref 3) it is clear that whilst thetotal numbers of craft produced each year is not increasing rapidly, the averagetonnage per craft is increasing quite substantially such that the industry as a whole iscontinuing to grow at about 15% per year as it has done since the mid 1970's.

The number of passenger only craft built per year has levelled off and reached a peakafter about 20 years of continuous growth. The tonnage of passenger/vehicle craftproduced per year is clearly in its infancy and may have a decade or two of furthergrowth. The build of fast freight tonnage has not started in earnest but the technologistsare clearly knocking loudly on the door of potential operators. The economics ofoperation is now the critical factor - the technology is waiting to be exploited.

References

1. Maritime Reporter, June 1996

2. RO-RO Technology, 1996, ISBN 91-87624-26-5

3. Jane's High Speed Marine Transportation 1995/96, ISBN 0-7106-1370-9

High speed craft tonnageordered worldwide over last 25 years

Tonnage (Lightship), Thousands100

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40 L// II

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70/75 75/80 80/85 85/90 90/95

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Figure 1. Increases in fast ship tonnage ordered worldwide over the last twentyfive years.

Power requirements for two monohullcraft of equal length and displacement

Effective Power Pe, KW (Thousands)251

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Figure 2. Comparison of the effective power requirements for two craft of thesame length and displacement but one having a beam 50% greater than the other.These calculations are based on Series 64 data.

Comparison of monohull, catamaran antrimaran power requirements

Effective Power Pe, KW (Thousands)2001

150-,

100 4

K Ii

50-

70 80 90 100 110 120 130 140 150 160 170 180

Waterline length, metres

V=5Okts, Disp=3000t

Trimaran Catamaran Monohull

Figure 3. Comparison of effective power requirements of a monohull, catamaranand trimaran (with all three hulls the same length) based on a commondisplacement and design speed.

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Figure 4. Merchant fleets or the world (Oceangoing ships or over 1000 grt).Numbers of merchant ships by functional group.

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THE EURO-EXPRESS CONCEPT -APPLICATION OF SLENDER MONOHULL DESIGN TO FAST VESSELS

byMr. Kai Levander, Vice-PresidentKvwrner Masa-Yards, FINLAND




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Kvmrner Masa-Yards Technology Page 1

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Kvarner Masa-Yards Technology Page 3

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Kverner Masa-Yards Technology Page 8

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Kvwerner Masa-Yards Technology Page 9

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Kvarner Masa-Yards R3D

ResearchDevelopDemonstrateDisseminate


THE TECHNO-SUPERLINER CONCEPT

byDr. Kazuo Sugai, Consultant

Japanese Shipbuilding Research Association, JAPAN




The Techno-Superliner Concept

Kazuo SugaiConsultant,

Japanese Shipbuilding Research Association

1. IntroductionThe R & D Programme of Techno-Superliner(TSL) started in 1989 by the TSL Associa-tion which consists of seven leading shipbuilders in Japan. A target of the Programmewas to accomplish technological foundations for a super high speed ocean going cargovessel, named " Techno-Superliner" with a performance of 50 knots in speed, 1,000tons in payload and over 500 nautical miles in range. In addition, sufficient seaworthi-ness of the vessel capable to navigate on schedule, even though in such a rough seaas the sea state 6 was desired.

Elemental technologies necessary for the ship were studied for 4 years on the firststage of the Programme from 1989 to 1992. In order to confirm completion of theelemental technology and to verify the performance of the Techno-Superliner in total,large scale models of the ship were built and tested at sea on the second stage of theProgramme in 1993 and 1994. Then, fundamental technologies for designing andbuilding of the ship had been accomplished as a hardware. However, much problemyet remains as a software to put the Techno-Superliner to practical use in physicaldistributions. Experimental voyages for practical cargo transportation at some routes,including the handling in the harbours were carried out in 1995 fiscal year, by using theair cushion type test ship. The R & D Programme for 7 years was finished completelywith a great success on March of this year.

This paper describes an outline of the R & D Programme, in particular, emphasizing onthe concept of the ship as a hardware. Moreover, a new concept of the physicaldistribution system in which the Tehcno-Superliner should be utilized is considered.

2. Background and Establishment of The TSL AssociationConventional merchant vessels such as those represented by tankers, bulk carriersand container ships still play a significant role in mass transportation comparatively at alow speed. Meanwhile, ongoing changes in economic social structures such as small-lot but high added value production with a wide variety and dispersion of production

-1 -

facilities both domestically and abroad require much faster marine transport. Truckingis progressing rapidly in land capitalizing on door-to-door service at a reasonable rate,but road hauling has suffered from traffic congestion, a shortage of drivers and pollutionby the exhaust gas.

As a possible solution to these problems, a proposal of the modal shift from motorfreight to marine transportation has drawn nationwide attention. Although slower thanother modes of transport, ships offer large cargo capacities. If the problems of speedand punctuality could be overcome, the modal shift to marine transportation would be-come practicable.

This supposition led to the biginning of the Techno-Superliner R & D Programme. Forthe sake of it, Technological Research Association of Techno-Superliner was inaugu-rated in 1989 by seven leading shipbuilders in Japan. A term of the R & D Programmewas planned for 7 years as shown in Table 1. It consisted of three stages, viz., the firststage for the elemental technologies, the second stage for the experiments at sea bylarge scale models and the final stage for experimental voyages. The goal was con-sidered to provide technological foundations for designing and building of Techno-Su-perliner and to make the ship ready for practical use.

Table 1 Schedule of the R & D Programme

M R&D Schedule (Fiscal Year] Late 1990s

1989 1990 1 1991 1992 1993 1994 1995Basic research for the Techno-Superliner ISI I - xei m na

Elemental research I Vlro nt a for•Tank test ii psfo

* Simulation p practical ISmetc. cargo trans. I .Ietc. I portation W

I of large-scale models 0t 'Wand at-sea tests using models I - II - Hydrofoil-type hybrid hull

Air-cushion-type hybrid hull If'" "I " J

3. The Concept of The ShipOne of the most important problems on starting the Programme was how to sellect themost pertinent concept to the Techno-Superliner. The concept should be not only witha high performance of the ship itself but with a high possibility of the realization as acommercial cargo ship.

-2-

There are three forces to support a total ship weight, viz., buoyancy, dynamic lift and airpressure. Each of them shows advantages and disadvantages itself as the ship sup-porting force and no one can satisfy individually the four main requirements of such alarge and high speed ship like the Techno-Superliner as mentioned in the above.Therefore, the pursuit of the most pertinent hybrid hull form concepts which combinethe supporting forces in multiple was considered inevitable. At the first stage of theProgramme, we started the study in selecting two kinds of hull form concepts as mostpromising ones.

The one is a hydrofoil type hybrid hull form concept (TSL-F) which consists of an upperhull, a fully submerged lower hull, hydrofoils and struts as shown in Fig. 1. To avoidthe influence of the sea surface, the upper hull with the cargoes aboard is sustained inthe air by dynamic lift of the main hydrofoil together with buoyancy of the submergedhull at a height not to be hit by waves.

Generally, when a total weight ofthe ship is suspended by the dy- Upper hull

namic lift together with the buoy-ancy, there is an optimal ratio ofthem depending on each weight Water-etand speed. When a higher speed -z

is required, the concept support-ed by dynamic lift only is superiorand when a larger total weight is Submerged hull

required, the concept supported Hydrofoil

by buoyancy only is advantageous. Fig. 1 Hydrofoil type hybrid hullAt a speed of 50 knots, one of the form concept ( TSL-F)most favorable concepts utilizing the dy-namic lift and the buoyancy is a hybrid type in the range of the displacement between2,000tons and 8,000 tons. In the case of the Techno-Superliner, the ratio of the dy-namic lift to the buoyancy is considered about 1:1.

This concept features supperior seaworthiness, in particular, easy ride, because nohull element exists near the water surface except the struts. On the contrary, com-paratively a large engine power necessary and a poor stability without natural restora-tion were considered to be improved. Besides, comparatively a deep draught in harbourwas considered to be another shortcoming.

-3-

The other is an air cushion type hybrid hull form concept (TSL-A) which consists of acatamaran and an air chamber partitioned by a bow seal and a stern seal. The totalship weight is supported by the air pressure mainly and the buoyancy of the catamaransubsidiary, as shown in Fig. 2.

JLouverThis concept is very similar to Hull

the usual surface effect ships, Air vent for

though it has comparatively cushion

long and narrow dimensions Uw

due to its large ship size. fi

Besides, it is equipped with Side hulls

control fins under water to Water-jeIinlet

improve the seaworthiness. (Viewed from below) Stem seal

Fig. 2 Air-cushion type hybrid hullform concept ( TSL-A )

The concept features superior powering performance due to its small hull form resis-tance and light structural weight. However, anxiety still remains on its comparativelypoor seaworthiness, in particular, high level accelerations and fragilation of seals. Theseweaknesses were also considered to be overcome in the Programme.

4. Elemental TechnologiesFour research items were considered to be necessary for developing the Techno-Su-perliner as follows;(1) Pursuit of new hybrid hull form concepts with high performance,(2) Application of new materials and adoption of the most reasonable hull structures,(3) Sufficient and reliable waterjet propulsion system,(4) Sophisticated motion and ride control technologies.

These items were studied by every technological means such as tank tests, laboratorytests and computer simulations on the first stage of the Programme.

Above all, main effort was made to complete the ship concept with a reasonable shipconfiguration and high controlability in the case of TSL-F. The reasonable ship con-figuration has attained through the consideration of an optimal slenderness of thesubmerged hull, pertinent design of the hydrofoil which works under the interaction ofthe submerged hull and the water surface and clearance between the bottom of theupper hull and the sea surface. The smaller number of struts yields the better resis-

-4-

tance performance, however, it causes anxiety of the structural weakness, especiallyof the vibration problem. We believe that the present configuration of TSL-F is one ofthe best solutions in which the powering performance had been improved about 10%off the initial design. Computer aided control system plays very important roles in theTSL-F concept, in particular, on the occasion of not only motion control in waves buttaking off & landing and bank turning. The control surfaces were designed so as to bewithin the cavitation free conditions. The total system consisted of computers, varioussensors and hydraulic driven flaps worked very well with a new designed algorithm.

Much effort was made to achieve better seaworthiness and lighter ship weight in thecase of the TSL-A . The excellent seaworthiness capable to sail in the sea state 6 hasbeen attained through investigations into the thoughtful wet deck design and thesaphiphisticated ride control system by fins and louvers. Adoption of special materialand shape for the seals led to the extension of the maintenance period. A new designmethod for the ship structure which is made of aluminium alloy has been developed bymeans of so called "Advanced Design by Analysis". About 10% of lightening wasattained through investigations into the computer culculatfons by the finite elementmethod and the fatigue tests on the main frame member fabricated by welding.

5. Experiments at Sea by Large Scale Ship ModelsExperiments at sea by using large scale ship models were carried out on the secondstage of the Programme. The purpose of the experiments was to confirm completionof the elemental technologies which we investigated on the first stage of the Programmeand verify the performance of the Techno-Superliner totally at sea.

Both two concepts of large scale ship models were designed and built for the experi-ments. The scale of the TSL-F ship model was decided as 1/6 of the actual ship.Although the ship speed corresponding to Froude's number is about 20 knots, how-ever, the design speed was raised to 40 knots so that observation of cavitation at thesame cavitation number as the actual ship became possible. The shape and dimen-sion of the submerged parts such as the hydrofoils, the submerged hull and the strutswere similar to the actual ship, though the upper hull above water was somewhat big-ger and heavier than the corresponding weight of the actual ship, because of the highcorresponding speed. Materials of the ship structure were stainless steel for the sub-merged parts and aluminium alloy for the upper parts. The propulsion system was anaxial type waterjet pump with an inducer driven by a gas turbine of 3,800 PS. Twotypes of inlets for waterjet pump, viz., a ram type and a flush type with an adjustable lip,were provided to evaluate difference of the performance. A general arrangement and

-5-

principal particulars of the TSL-F ship model are shown in Fig. 3.

The scale of the TSL-A ship model was decided as 1/1.8 of the actual ship, the lengthof which is 127m. The reason was that the larger scale is the better to understandbehavior of the ship under the influence of water and air cushion simultaneously. Thedesign speed was decided as 50 knots in still water to realize some phenomena at theabsolutely same speed. The ship structure adopted a longitudinal frame system madeof aluminium alloy, as the same as the actual ship. An analytical method was appliedto the ship design, in which a severe environmental condition like real seas was given.The ship model was propelled by two sets of waterjet propulsion systems driven by a16,000 PS gas turbine each. The control system consists of sensors, computers andfins with flap control. In addition, louvers were fitted for freeing the pumped up airpressure in waves as the ride control system. A general arrangement and principalparticulars of the TSL-A ship model are shown in Fig. 4.

The TSL-F ship model was constructed at kobe Shipyard of Kawasaki Heavy IndustriesLtd. and was completed in April, 1994. The model was named "Hayate" (which meansgale in Japanese). The fore part of the TSL-A ship model was built at TamanoShipyard of Mitsui Engineering & Shipbuilding Co. Ltd. and the aft part was built atNagasaki Shipyard of Mitsubishi Heavy Industries Ltd. simultaneously. The fore partwas transferred to Nagasaki aboard of a barge and joined with the aft part on the dock.The model was completed in June, 1994 and named "Hisho" (which means flying inJapanese).

The TSL-F ship model succeeded to make taking off and landing very smoothly andattained 41 knots at the trial in April, 1994, as just predicted by the tank test. After that,various kinds of the experiments such as performance tests, cavitation tests,maneuvrability tests and control tests were carried out in Osaka Bay. The photographof the TSL-F ship model during the experiment at sea is shown in Photo. 1. Throughthe experiments at sea, the reasonable configration of the TSL-F was confirmed, as theship could sail just what we expected. Moreover, the design of control surfaces andthe algorithm was so proper that the total control system worked very well for keepingthe ship attitude appropriately, even in waves and in transient conditions like the takingoff and landing.

The TSL-A ship model started at sea tests off Goto Island of Nagasaki Prefecturewhere she succeeded to attain the maximum speed of 54 knots at the trial, much fasterthan the designed speed. After finished the performance test in still water, the ship

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SIDE VIEW

-- -- - -- ------• .,3 ' _ . ;

SECTION

Principal Particulars of TSL-F Ship Model

Scale about 1/6(Length of the submerged hull of the actual ship is 85.0 m)

Upper hull Length over all 17.10 mBreadth moulded 6.17 mDepth at the midship 3.35 m

Submerged hull Length over all 14.17 mDiameter 0.93 m

Main hydrofoil Maximum breadth ( incl. Side pods) 6.36 mDraught (from the bottom of the Submerged hull)

Draught in ship borne condition 3.13 mDraught in foil borne condition 1.60 m

Design speed 40 knotsMain engine Gas turbine 3,800 PS X 1Propulsor Axial type water jet pump X 1

( with the reversor and the deflecter )

Fig. 3 General arrangement and principal Particulars ofthe TSL-F ship model

-7-

SIEVIEW

,~ ý z i ,

FACE

UPPER DECK

~~~~... ....... .. .:: ::i ............°

BACK

Principal Particulars of TSL-A Ship Model

Scale 1/1.8(Length of the actual ship is 127 m)

Principal dimensions Length over all 70.0 mBreadth moulded 18.6 mDepth moulded ( till the upper deck) 7.5 mDesign draught ( in off cushion cond.) 3.5 m

( in on cushion cond.) 1.1 mDesign speed (in still water) 50 knotsMain engines Gas turbine 16,000 PS X 2Propulsors Water jet pump X 2

( with the reversor)Engines for lift fan High speed diezel engine 2,000 PS X 3

Gas turbine 2,000 PS X 1Seals Fore seal Full finger type

Aft seal Lobe type

Fig.4 General arrangement and principal particulars of

the TSL-A ship model

-8-

moved to Chiba Prefecture to conduct the performance test in waves in the PacificOcean. Through the experiments from July to November in 1994, various kinds ofexperiments such as performance test in waves, maneuvrability test and control testswere carried out. The photograph of the TSL-A ship model during the experiment atsea is shown in Photo. 2. The maximum wave height that the test ship met during theexperiments was 4m in the significant scale. As the result of the experiment, highperformance of the TSL-A was confirmed even in rough seas. In addition, as themeasured structural data showed a good agreement with the prediction, it was be-lieved that the design method for such a large ship structure made of aluminium alloywas established.

Photo. 1 The TSL-F ship model dur- Photo. 2 The TSL-A ship model dur-ing the test at sea ing the test at sea

Although featuring superior characteristics each, it is convinced that both of the TSL-Fand the TSL-F concepts can satisfy the requirements of the Techno-Superliner almostcompletely.

6. Experimental VoyagesMuch problem yet remains as a software to put the Tech no-Superliner to practical use.In order to solve the problem, experimental voyages using the air cushion type test ship"Hisho" were planned and conducted in 1995 fiscal year.

Among the problem, following items were considered to be solved first;

(1) Safety navigation operated by a small number of crews, even in nighttime andconjested sea areas,

(2) Transportation in the sequence of door-to-door system including the cargo handlingin a harbour,

(3) Acquisition of data necessary for the shipping business.-9-

For the purpose, the test ship "Hisho" sailed around Japan from Hokkaido Island toKyushu Island, not only in the Pacific Ocean routes but in the Japan Sea routes. Throughthe voyages she ran about 17,000 nautical miles in total at the average speed of 45knots even in considerable rough seas without any trouble. The test ship could beoperated by 6 crews safely even in a long route and in nighttime. The total number of100 containers packing various kinds of cargoes such as fresh foods and high addedvalue products were transported as the test in several routes. Any damages andharmful effect on cargoes did not happen during the voyages. About a half day timesaving compared with the trucking in land was achieved in the long routes. Photo. 3shows the test ship "Hisho" was on her experimental voyage with some actual contain-ers on the board.

Photo. 3 The test ship "Hisho" was on her experimental voyagewith the actual containers on the board

The actual ship of the Techno-Superliner is supposed to carry 150 standard size con-tainers as two layers on the deck. A high speed physical distribution system requiresmuch faster cargo handling in harbour. The container loading/unloading tests withnew cargo handling facilities were also conducted in some ports. These facilities hadbeen developed in parallel with the TSL Programme by the other organizations thanours. There are two systems, viz., the one is so called "Horizontal System" with arobotic vehicle which transfers the containers between the ship and the pier throughthe ramp and the other is so called "Vertical System" utilizing conventional cranes witha special spreader. Both of them handles an unit of 4 containers at the same time andby that means about 3 times of the cargo handling efficiency compared with conven-tional means was realized. Photo. 4 and 5 shows the horizontal and vertical systems

-10-

respectively.

T0'A"

Photo. 4 The horizontal cargo Photo. 5 The Vertical cargo

handling facility handling facility

Many data useful for the practical shipping business like as the fuel consumption, the

schedule keeping and the maintenance problem were obtained through the experimen-

tal voyages. The speed reduction in waves was not so heavy than we supposed

before as shown in Fig. 5. Besides, the fuel consumption was just the same as we

predicted by the data on the working test of the gas turbine in land. The life of the seals

was furher long than that we expected before.

2 120

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Fig. 6 Spccd roductian i n waves

- 11 -

7. ConclusionsThrough the R & D Programme, the fundamental technology for designing and buildingof the Techno-Superliner has been completed as a hardware. In addition, variousproblems on the practical cargo transportation using the ship were investigated as asoftware. The member shipbuilding companies are now ready to accept the order andsupply the ship. However, a remaining barrier to the practical use is only the problemof transportation economy. Although the Techno-Superliner can transport a lot ofcargoes about a half day faster than the trucking in land in the case of 1,000 kilome-ters distance, the cargo rate of the Techno-Superliner is still 20% higher than thetracking. As a target of the rate would be finally the same level as the tracking, aneffort should be continued to reduce the building cost and the fuel cost. Meanwhile,arrangement of the infra-structure and the safety rules and regulations for the Techno-Superliner transportation system is also urgent. When these problems were solved,the Techno-Superliner will be able to make debut by the end of this century and breaka new field in high speed seaborne cargo transportation not only in Japanese domesticroutes but also in East Asia routes.

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SES CONCEPTS

byMr. Geir Rise

LundMohr & Gaiever, NORWAY




SES CONCEPTS September 13 1996Pace : I

Presentation at WEGEMT Workshop on

CONCEPTUAL DESIGNS OF FAST SEA TRANSPORTATIONUniversity of Glasgow, Friday September 13 1996.

SES CONCEPTS

ByMr. Geir Rise, B.Sc. Engineering ManagerIngeniorene Lund, Mohr & Giever-Enger As - LMGE ,Bergen - Norway.

1.0 Introduction

The following paper is called SES CONCEPTS, and features 2 SES projects in Norway. Bothprojects are military, and they cover the new class of Minecounter measure vessel (MCMV),and the new class of Fast Patrol Boats (FPBs). The paper aims to highlight the some of thespecial reasons for using the Surface Effect Ship principle as a ship platform.

2.0 General comments on Surface Effect Ships

Surface effect ships are being used for a number of different applications. The most widelyused application has been for the transport of passengers. Passenger crafts have been built inthe UK, Norway, USA, Korea, Australia and Belgium.There has also been built a number of demonstrator crafts or prototypes, the most well knownhave come from Germany, Sweden, France, Russia, USA and Japan.Like any other craft, the SES has its weak and strong points. There are many routes around theworld which are ideal for an SES, perhaps with long open rough stretches. Due to thefrequency response inherent in the craft type, sea sickness incidence is reduced. There are alsoexamples of ideal routes from catamarans, where the speed and comfort is ideally suited for theroute.As designers of high speed crafts, we are not advocates for any particular craft type, but weare able to see the different advantages and disadvantages with the crafts.

The most commonly known characteristics of an SES are:

" Comparable favourable resistance characteristics compared to other high speedcrafts

+ Very high speed potential+ Very favourable seakeeping qualities

- Extra systems installed compared to catamarans and monohulls- Reduced motion comfort in the lower seastates

IGENIORENE

L"UND. MOHR & GIU'VER-ENGER A.S

SES CONCEPTS September 13 1996Page : 2

It is perhaps true to say that the SES have not achieved the overall widely use as other twinhulled crafts. There are several examples of routes operated by SES where the passengernumbers increased by 50% with the introduction of a SES, due to the higher speed capability.There are also examples of the same due to the improved seakeeping qualities of the SES. Thepassenger SES is operating in many open ocean routes, like Malta- Sicily, the Baltic Sea, offthe coast of Brazil and in Japan.

Nearly all of today's passenger SES have lengths below 40m. It is difficult to point out thereasons for this, since we are today seeing an expanding number of large high speed crafts. Thelarge expansion of new high speed crafts are today coming from the above 40m lengths, andthis market is booming, both for monohulls and catamarans. It is interesting to see the interestamong traditional passenger/car ferry operators to venture into new craft types, and new waysbf operation. It could seem like the development of SES crafts in the late eighties halted , forvarious reasons.The most notable large SES projects that did not come into production were:

- The 3K frigate program in the US- The Cardinal MCMV program in the US- Various 60m and 90m passenger/car ferry designs from Norway and Germany.

It may be correct to say that craft performance is more critical than catamarans and monohulls.This is partly due to that there are more factors involved which determine the performance. Toobtain the required performance, it is of vital importance that the SES craft have the correctrunning trim, the lowest possible weight and the correct longitudinal position of gravity. Wehave seen examples of SES designs that have been built with excessive weight, suffering fromspeed and comfort penalties. A higher weight than the design weight may result in the craftoperating on a lower cushion factor, with increased resistance. This also may lead toinsufficient liftfan capacity, which again prohibits the use of any motion damping system.

The SES have been criticised for having some many additional systems, like electronics,hydraulic actuators and mechanical devices for motion control purposes. It is however a pointof interest, that today no catamaran or even monohull over a certain size is delivered withoutany active device for controlling either pitch, heave or roll motion.

3. The SES as a military ship platform.

The presentation features 2 platforms for military application in Norway . Both crafts areunique for this application, which is The minecounter measure vessel and the new Fast patrolboat. The MCMV consist of a class of 4 minehunters and 5 minesweepers. The RoyalNorwegian Navy have several of the minehunters in operation, delivered form the yard ofKverner Mandal. In late August this year, the contract for building the prototype for the newFPB class was awarded to the same yard. After the FPB prototype has undergone technicaland operational tests by the navy for a 2 year period, a class of 7 series crafts may be built.

x*s GENIORENE

LUND. MOHR & GIEVER-ENGER A.S

SES CONCEPTS September 13 1996Page : 3

4. The MCMV platform.

The typical MCMV designs are as many other navy crafts very conservative, consisting ofmonohulls constructed in FRP. Both the craft type, and the building materials for theNorwegian MCMV are special, using an SES made in the FRP/Sandwich construction method.What were the reasons for using an SES as a platform for the MCMV ?It is of interest to consider the requirements laid down by the Navy, and to highlight theinherent advantages of the craft principle.The most important aspect of the Norwegian SES Minehunters are:

SHOCKDue to that the craft is operating on an air cushion and only a smaller fraction of thehull is under water, a lower magnitude shock is transferred to the hull structure andto the equipment onboard. Several shock tests were done both by a full scale model,and the first minehunter. All the test results were very satisfactory, with shock levels farbelow any other MCMV.

SYSTEM INTEGRATIONOne of the key elements in the requirements of the SES platform, were that the lowermagnitude shock levels would require equipment with lesser degree of MIL standard,and also less complex mounting systems could be adopted. This again would lead toreduced costs of the craft.. Unconfirmed information reveals a price difference of 40%up to the nearest monohull contender.

PLATFORM SIZEThe craft has a massive internal volume, and a large platform size for equipment andcrew.

ARRANGEMENTNearly all systems onboard are located above waterline, which enhances safety, lowersthe acoustic signature and reduces the vulnerability

OPERATIONThe craft operates on a draught of less than I m, which makes it ideal for shallowdraught operation and enhances vulnerability

SPEEDThe craft has a transit speed up to 25 knots with the installed diesels.

The results so far from operation and tests of the craft show that all requirements have beenmet.

k sNGEN10REN E

LU ND. MOHR & GIEVER-ENGER A.S

SES CONCEPTS September13 1996

Page: 4

5. The Fast Patrol Boat.

The latest SES project in Norway is the new FPB for the RNON. The project is part of aprogram which involves refurbishment of 14 units of the Hauk class of existing FPBs, anddelivery of 1 +7 of the new class. The plan is to deliver the first craft as a prototype, which willbe a demonstrator for testing out the concept itself as well as the different weapons systemsonboard.The craft will be constructed in FRP/Sandwich according to the same production processesand materials as the minehunters.

The craft has the following characteristics

Length o.a. :47.0 mLength pp :41.5 mBeam mld :13.1 mBeam o. a. 13.5 mDepth : 6.3 mCrew : 15Propulsion arrangement : CODOG with watedjetsInstalled propulsive power :2 x 6000 kW / 2 x 370 kWInstalled liftfan power :2 x 730 kWDisplacement 260 tonsSpeed potential 55 knots +

The project started in 1989 and the main requirements of the craft were laid down in 1993.Several alternative craft concepts were evaluated, both monohulls, catamarans and SES. Themain objective was to meet the requirements with the most cost efficient solutions. It was alsoevaluated whether the new class of FPBs should have peacetime functions, like environmentalsurveillance, search and rescue, personnel transport etc.It became apparent that the alternative functions had to be reduced to a minimum.

As a result of all the analysis and evaluations, that the SES would totally meet the requirementsin the best way as a ship platform for the weapons package..The main parameters for this are:

SPEEDThe SES platform gives the highest speed for the same power compared to the otheralternative craft types. It also gives the best fuel economy , especially for the increasing speeds.

The craft has a dieselengine installation for slow speed loitering, with a max speed potential of

6 knots, The installed gasturbine has a max.continous output of 2 x 6000kW.The craft has top speeds in excess of 55 knots.

SEAKEEPINGThe craft dynamics of an SES is typically characterised by dominant response at higherfrequencies than catamarans. While the catamaran has a dominant response in the sub Hz area,the SES response is above Hz. This means that the SES response lies in an area where the

hING ENI0NE

LUND. MOHR & GIEVER-ENGER A.S

SES CONCEPTS September 13 1996Page: 5

human body is less susceptible for seasickness. Consequently, although there is definitelymovement on board an SES, this is dominant at higher frequencies.

PLATFORM SIZE.The platform gives a very functional arrangement.From safety and vulnerability viewpoints, all important systems are mounted above waterline,and some of them above maindeck. Stability is excellent, and even flooded stability for 2compartments gives possibility for operation of critical systems / weapons.

SIGNATUREThe ship platform gives very good stealth characteristics, low optical and IR. signature.The outer panels are faceted and the construction makes use of special materials.

WEAPON INTEGRATIONThe craft will be equipped with very powerful and versatile weapons package, and most of theweapons are integrated into the main hull. 8 surface to surface missiles will be integrated andlaunched from the sheltered main deck aft.

6. Conclusive remarks

The craft is well documented through extensive research and engineering work. Model test atI in 10 scale were carried out at the University in Trondheim for resistance and waterjetcavitation tests. A free running self propelled model of the same scale was also tested, mainlyfro dynamical stability. Computer fluid dynamics analysis was carried out to calculate the airresistance, dynamic lift and lifting mornent.The hull structural calculations have beenperformed, and extensive weight calculations have been done.Seakeeping prediction analysis have been done .In order to investigate the structural impact and temperature response of the missileinstallation, full scale tests were done, This was done to investigate the consequences of anunwanted firing of a missile or a case where the fired missile was not allowed to free.The blast duct are made in composite materials, and the tests consisted of firing 2 starterengines of the missile without letting the missile free. The results were positive, which loweredthe risk for the total missile arrangement.

The coming phase will consist of yard verification of the work that the Navy have undertaken,and subsequent construction and testing.

The Navy will conduct a 2 year test and trial period after the prototype delivery.In this period the Navy must decide if this concept wvill perform the functions of an FPB andmeet the requirements. If so, the series production will commence, and up to 7 craft may bebuilt.

\-7rs INEMSI0ENE

LUND, MOHR & GhEVER-ENGER A.S

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THE COMMNIERCIAL REQUIREMENT FOR A NEW SHIPPING INITIATIVE

byMr. Geoffrey Phillips,

Thorneycroft Giles and Co inc, UK

Paper presented at theWEGENIT Workshop on



WEGEMT Workshop

on the

Conceptual Designs of Fast SeaTransportation

The Commercial Requirement for a New Shipping Initiative

by Geoffrey PhilippsCommercial Director - Thornycroft Giles & Co Inc

Friday September 13th 1996

The Commercial Requirement for a New Shipping Initiative:by Geoffrey Philipps

Commercial Director - Thornycroft Giles & Co Inc

Ladies and gentlemen, good afternoon. It is a great pleasure and honour to be herewith you today at this symposium. By way of introduction, my' name is Geoffrey Philippsand I am the commercial director of Thomycroft Giles and of FastShip Atlantic Inc. I feela little intimidated here this afternoon being a commercial animal amongst suchtechnical talent. I will however attempt to tame you by putting a slightly different lighton the proceedings this afternoon and sharing with you some of our experiences atThornycroft Giles in establishing what is the potential market place for fast freightservices and try to identify what are the important issues that concern the shipper.

I think it is fair to assume that for the foreseeable future there is no requirement for bulkcargoes to move fast by sea. Therefore we are addressing only the container and RoRotrades of today with a possible exception of the reefer trade.

Traditionally the shipping industry has been concerned with building vessels that havea market position from the shipowner perspective. I can remember one occasion in theearly days of containerisation when a leading liner operator decided that they shouldenter the world of containers, after all everybody else was doing so. The board ofdirectors asked the technical and commercial departments to advise as to what vesselsshould be built. The proposal put before the board was for four ships of 40,000bhp, theboard in its wisdom decided that there should be five ships of 50,000 bhp because thenumbers were rounder. That company is no longer in shipping - things have improvedbut still there is a very wide gulf between the shipper and the shipowner and theproblem for the shipyard is that its customer is the shipowner and it does not have theproper access to the real buyer - the shipper. How on earth can the designs bedeveloped properly under these circumstances.

The requirement for speed for passenger traffic is now well accepted. With somecompanies, the realisation of consumer demand has only come about after theircompetitors have stolen a march. It is only now that the shipping industry is starting tounderstand that its customers are also interested in the faster carriage of goods by sea.

Over the past two decades there has been considerable change in manufacturingindustry. Increasing competition from the emerging nations has resulted in a substantialrationalisation of production processes. There has been a significant investment inmechanisation and computerisation. Now the benefits from further investment are verylimited in terms of profit generation, manufacturers are having to look at other areas inorder to enhance their competitive stance.

The focus is rapidly turning to logistics. From a domestic market stand point a greatdeal of progress has been made in the area of logistics, improving response times andreducing pipeline stock. The growth of the third party logistic industry is evidence asto the emphasis that manufacturers are now placing on the whole logistics question.

Some of the results are also very significant. Two years ago General Motors contractedout the distribution of its spare parts within the United States to a single third partyprovider. This company handles the whole parts operation from supplier to dealer. Inthe process the average response time has been reduced from 28 days to 48 hours.The reduction in stocking levels at forward stocking points was, as you can imaging,substantial. The benefit both from a financial and a customer perception point of viewwas significant.

Land based logistics system particularly in the United States are now well developed.In Europe the more fragmented nature of the transport industry and the differingnational regulations make the move to better logistics systems more difficult. Whatdoes not exist today however is a meaningful logistics solution involving a significantshipping element.

Is the pursuit of higher speeds commercially realistic or is it the fantasy of a limitednumber of yards and naval architects? At Thornycroft Giles we have spent aconsiderable amount of time talking to the potential customer base to establish thedynamics of the whole international logistics chain. There is absolutely no doubt thatthe customers are looking for a substantial change in the way their goods are handled.In looking at any new cargo concept it is important to establish the real priorities of thecustomer base and that is not necessarily speed.

Shipping is a very conservative industry, it resists change. The introduction ofcontainerisation in the early 1960's was a major event but it brought no real benefit tothe shipper other than to reduce pilferage. Transit times are actually no better than theywere with the old finer vessels. In fact the service levels have not effectively changedsince the introduction of steam! The Cutty Sark regularly achieved 17 knots whichoverall compares very favourably with modern day transit times.

At Thomycroft Giles we regard ourselves as a logistics company. We have specialisedin the development of advanced seaborne logistics systems which are designedspecifically designed to operate along side the existing land based logistics systems.

Let us for a moment dwell on the North Atlantic trade. If you talk to shippers they willtell you that if everything goes right, it rarely does, they are able to move goodsbetween Europe and the United States in 14 day on a door to door basis. This answercompares reasonably with the advertised sailing schedules. This is less than half thestory. Ask a shipper what transit time he budgets for in planning his stock levels. Askhim what he contracts against. The answer will vary considerably. At the low end it is20 days, overall the mean is in the 22-23 day range but some will go as high as 30days. This is the aspect that the shipping companies tactfully ignore in their promotionalefforts.

What does the shipper really want. He is shipping more and more higher valuemanufactured or part manufactured goods and is following a rapidly increasing globalsourcing policy. The answer does not necessary point towards faster vessels but inorder of priority we have found the key issues to be:

2)

ReliabilityFrequencySpeed

It is the same as the requirements for land based logistics. Speed on its own isinconsequential, without reliability it has absolutely no benefit. Many different highspeed concepts have been proposed which address the questions of speed but appearto ignore the matter of sea keeping.

Traditionally the problem for any operator of a liner service is weather. It is very difficultto maintain schedule on many of the worlds key trade routes. Port congestion adds tothe problem and one finds that companies often miss out port calls in order to regainschedule. This erodes customer confidence and causes considerable extra costs interms of additional land hauls.

If you look at the US Government statistics on port operations some amazing numberscome to light. Take for instance the figures for the arrival of container vessels fromEurope on the US East Coast between February and July 1994. We find that over 50%of the services arrived on the wrong day when compared with their schedule. One mustalways be careful with statistics. A vessel due at 11 pm could arrive at 1 am thefollowing day and be judged to be on the wrong day, but equally a vessel arriving at11 pm against a 1 am schedule is regarded as having arrived on the right day. In landbased logistics times are measured in minutes therefore in any new deep sea seaborneconcept we should at least strive to work within a small number of hours.

It is the inability of the current services to provide high levels of schedule reliability thatcreated the largest single problem for the international logistics chain. The unreliablescheduling prevents the building up of an effective link between the sea leg and theland systems. Therefore I would suggest that when seeking new logistic orientatedconcepts we should be careful not to simply try and use the old, well tried, principles.We should seek out new methods.

In studying new concepts it important to look at the whole logistics chain. A problemexists in the ports where a very substantial investment continues to be made in asystem that is at best inefficient from a logistics point of view. The arrival of the largervessels will only serve to exacerbate this problem.

The shipping industry in its wisdom has decided that the way forward is for biggervessels. There is a continuous struggle to bring down slot cost because this is seenas the shipper's primary concern. There is no doubt that the market place is driven byvolume discount with no position for service levels. Why? Because, with an almostpermanent over supply of slots, the shipper is always driving down the rate, theshipowners are easy meat. Innovation is not something that comes easily in thecontainer world, the severe level of competition only means that any small improvementintroduced by an operator has to be sold without any rate premium and any marketingadvantage is very quickly eroded away What is needed is a completely differentapproach which can provide a totally distinct level of service.

Is big really beautiful? If you look again at the Atlantic, a typical 2,500 teu vessel willtoday command a timecharter rate of UIS$25,000 per day or US$1 0 per slot. Assumefor ease of reference a 10 day transit time. This represent a podt to podt cost of US$1 00per slot add~about $25 for bunkers and the cost of the sea transit itself represents~only15% of a good contract rate across the Atlantic; for the small shipper it is a lot less.Bigger vessels are projected to reduce vessel slot costs 15-20%, a very small savingin the overall equation. This saving should then be compared with the additionalproblem cause on land by the larger vessels.

The container world is at a stage of flux. There is a consolidation of the larger linesstarting to happen. The smaller players will have to decide where their best options lieonce again. For the shipper the developments during the past week indicate areduction in choice and eventually a reduction in service levels. The larger vessel willbring about some longer transit times for cargo that are not originating or destined forthe larger podts.

One of the major errors that has been made by the shipping lines in the past is to shipall containers at the same rate irrespective of the value of the goods to the shipper. AsI have previously indicated, individual shipper volumes are what dictates the price. Theresult is that hay is shipped at the same price as auto padts. The advent of the largerships and a rapid increase in the world slot capacity leads to a mad scramble to identifynew cargoes. This inevitably leads to the shipping of lower value commodities. Todaythe largest single commodity shipped in container is waste paper! The problem with l owvalue cargoes is that they cannot afford long land hauls. To attract these cargoes astring must add more port calls. More podt calls bring more delays and therefore areduction in the service level.

The airlines long ago realised that the profit comes in the front of the plane, the backis filler. They design their services around the premium passenger to considerableeffect. Container shipping designs its service round the big volume shipper whichcoincidentally tends to be the low value shipper. The result is that the shipper whowould be interested in a premium level of service continues to be forced to travelsteerage.

The criticism of faster vessels is that they require much higher fuel consumptions. Thefirst thing that any ship owner asks about a vessel is its speed and consumption. Withsome designs the fuel cost on a per nm basis is five times that of the newer generationcontainer vessels. But for conventional vessels, as you can see, the bunker costrepresents only 2-3% of the overall the port to port cost.

None the less for deep sea applications the advent of greater speed will necessitatea premium rate but it is important to understand that the product is quite different froma conventional container service and therefore one is not involved in a box rate war ifthe required reliability and frequency factors are met.

At Thomycroft Giles we talk about the middle market, the market between Airtreight andconventional seafreight. In the case of airfreight the potential middle market transit

4

times are sufficiently similar to make a new cargo concept very attractive againstexisting air services due to a substantial rate differential. It is the service differentialthat has to be addressed in the competition with conventional container services. It isthe same as the competition between the postal services and the courier companies.On a domestic basis the postal service in Europe is very effective but we are allprepared to pay a significant premium to achieve a guaranteed delivery of a smallpackage ie to buy a certain level of service. Already in the middle of September we arestarting to see the last posting dates for Christmas being advertised!

To understand the reason for the shippers interest in a premium service one must lookat some of the dynamics and I will mention four examples which are not untypical.

Company A is a major manufacturer both in the US and in Europe. Parts andsub-components move between the production lines in Europe and the US andin some instances an individual component will cross the Atlantic four timesduring the production process. The major priority is to keep the production linesrunning therefore the company has a policy of moving anything that it requiresin less than 21 days by airfreight irrespective of the cost.

Company B ships a deep frozen material with a value as low as $20 per tonne.The material is shipped approximately every two weeks and is placed in coldstore before being released to the production line. The availability of a highfrequency, reliable service would allow the material to be taken directly into theproduction process without the handling in and out of cold store leaving only thesafety stock in store. The differential in handling costs is sufficient to justify asubstantial premium despite the very low value of the product.

Company C would like to ship a liquid product that over time will separate outto give a solid that cannot be discharged from the tank container. The onlysolution is to use a very sophisticated tank which cannot be justified on cost.Therefore the product is not shipped today. The reduced door to door transittime associated with a new logistics concept would be sufficient to prevent thefull settling to occur nd therefore allow the material to be shipped in aconventional tank.

Company 0 ships a material that has a limited shelf life at ambient temperatures.Today it is shipped by reefer at a considerable premium but a faster morereliable transit time would permit shipping in drybox

These four examples show some of the different aspects of a new logistics approach.None of them address the question of cargo value or inventory holding costs. Todaya substantial portion of the freight cost associated with finished articles relate toairfreight. The high airfreight impact is only there because there is no meaningfullogistics system associated with seafreight services.

The aircraft industry has developed its product substantially over the past 20 years.The result has been a substantial reduction in the real cost of air travel despite the high

5

capital investment that has been involved. Fuel economy and asset utilisation havebeen high on the agenda of an industry that understood the dynamics of supplyeconomics. With the introduction of the jet airliner at the end of the 50's no one couldof possibly have foreseen the market growth in air travel that would occur as a resultof improved logistics. The development of the industry has been design led.

In the same time shipping has not moved forward. Its market has grown as a result ofgeneral global communications not as a result of innovation in shipping. The industryis now at the stage where the aircraft industry was in 1955 - wondering whether itshould embrace new technologies or carry on with the DC3 - a stretched DC3 that is.It has been forced to use the same basic design concepts by a strong handed customer

The potential for significant advances in Gas Turbine power systems and waterjettechnology in particular are exciting to say the least. If we are to be able to reap thebenefit, the industry has to take its head out of the sand and understand what itscustomer really wants and why and when he is prepared to pay for it.

Ladies & Gentlemen, little has been achieved in the shipping industry over the pastyears. Your eventual customer, the shipper is looking for solutions, there are excitingpossibilities if you look into what has been achieved by other industries. Some newthinking is required, there is a tremendous potential for creative thinking and some veryexciting prospects. Please lets move shipping into the 21 st century rather than stayingin the 19th through design.

Thank you.

6

NEW CONCEPT HULL FORMS FOR FAST SEA TRANSPORTATION

byM.S.Shin, S.I. Yang, E.C. Kim,

Korea Research Institutes of Ships and Ocean Engineering, KOREA




New Concept Hull Forms forFast Sea Transportation

September 1996

Myung-Soo Shin, Seung-I1 Yang, Eun-Chan Kim

Ship Performance Department,Korea Research Institutes of Ships & Ocean Engineering,

Yusong P.O.Box 101, Taejon, 305-600, KOREA

ABSTRACT

This paper presents the results of the study on the conceptual design ofseagoing high-speed ships. The five concept hull forms are studied, this is a350 passenger class Hydrofoil-Catamaran, a payload 200 ton class Double BottomHydrofoil Catamaran, a payload 500 ton and a 1,000 ton class Air CushionCatamaran, and payload a 1,000 ton class Super Slender Mono Hull. All of theseships can be used as a passenger ship, car-ferry or container ship.

All of conceptual design work are focused on the enlargement of ship sizeand realization of actual ship, since all of main engine, propulsors, equipmentand hull structure can be manufactured without any special difficulties. Thedesign concepts, towing tank results and perspective view will be presented anddiscussed.

1. ]INTRODUCTION

Recently super-high speed hybrid crafts draw much attention since they canfill the gap between airplanes and conventional vessels. Many advancedshipbuilding countries invest to develop hybrid crafts for the purpose of securingthe high-speed vessel market in the 21st century[1,2,3]. To develop the newhybrid crafts, it is essential to create new concepts beyond conventional ideas.

In the present project, the new concept hull forms, 350 passenger ship, thepayload 200- 1,000 ton class hull forms are studied. In order to find out thefeasibility of newly developed concepts, the model tests were carried out and theresults were analyzed.

A 350 passenger ship, Hydrofoil-Catamaran concept is developed. Onepassive hydrofoil is attached to main hull to improve the resistance performanceand slender long bow is adopted to minimize the longitudinal motion. As aresult, this ship shows the reduction of power by at least 15% in comparisonwith a normal catamaran with equivalent seaworthiness. This ship shows fairlygood seakeeping quality due to the damping by attached hydrofoil and the wavepiercing effect by the slender long bow. Now, this ship has been operated insouthern coast of Korean peninsular as a passenger ship after a successfuldelivery.

The conceptual design of payload 200 ton, displacement 660 ton classcar-ferry is carried out. This hybrid hull form is supported by the combinationof lifting forces by hydrofoil, displacement and planing. The fore-part of hullform supports 250 ton of weight, iL e. 100 ton, 50 ton and 100 ton owing tohydrofoil, displacement and planing lift, respectively. The towing tank test showssome prospective view of seakeeping performance of this ship.

ACC (Air Cushion Catamaran) with bag and finger type bow skirts andtriple bag type stern skirt is designed as a car-ferry. The aim is to design thepayload 500 ton and maximum speed 50 knots class passenger car-ferry. Theresults of towing tank test show good powering performance so that the

maximum'speed might be maintained. Moreover, the transverse stability andseakeeping quality are satisfactory on cushion condition in sea state 6. It islikely that the design and construction of AGO will be possible and credible.

As an extension of this work, a payload 1,000 ton, displacement 2,500 tonclass AGC cargo ship is also developed. This hull form can carry 100-150 TEUcontainers.

A Super Slender Mono Hull of displacement type with the length of 120 m,and the breadth of 12 m is developed. To improve resistance and seakeepingperformances, L/E is chosen to be 10 and long and slender bow bulb is installed.The upper deck of bow is placed behind FP (Fore Perpendicular) for the betterseaikeeping. Displacement can be about 2,500 ton since payload-displacement ratiois higher than any other hybrid hull type, which requires lower engine power.

The design concepts, towing tank results and perspective view Will bepresented and discussed.

2. 350 PASSENGER CLASS HYDROFOIL-CATAMARAN

2.1 Design concepts of Hydrofoil-Catamaran

Before the creation of design concept, discussions were carried out toproperly consider commercial operations and system reliability as well as thepossibility of future scaling up of the development plan.

In order to minimize resistance and improve seaworthiness, the L/B ratio ismaximized and a passive foil is considered. The lift force of the passive foil islimited to between 30 and 40% of the design weight. The modified NACA-66section is adopted in order to suppress the generation of cavitation[4]. A sharpand slender long bow is optimized to minimize the resistance and thelongitudinal motions which severely affects the passengers and crew in acatamaran hull form.

Model tests of two types of hull and three locations of a passive hydrofoilwere carried out and the configuration of optimized hull form is shown in Fig. 1.Details of optimization procedure is described in [51 and model test results arediscussed in this paper. The principal dimensions are tabulated in Table 1.

2.2 Model tests

An 1/20 scale model was manufactured of urethane foam to reduce themodel weight and Fig. 2 shows the photograph of manufactured model ship. Thelength of model ship is about 2 m. Resistance and seakeeping tests were carriedout in the towing tank of KRISO.

In order to analyze the resistance of hull, the hydrofoil resistance isseparated from the total resistance.

II

FOIL SECTICON

Fig. 1 Configuration of foil, bow and stern sectionsof 350 Passenger Class Hydrofoil Catamaran

Fig. 2 Photographs of model ship of 350 Passenger Class Hydrofoil Catamaran

Committee)In the full-scale prediction, it is assumed that the sea condition is calm and

there is no wind. The frictional resistance coefficient is extrapolated by ITTC1957 Model-Ship Correlation Line.

The resistance of the foil is defined as follows.

RFo=CD. L PAV+ CF' LPAV, (5)

where A denotes the planform area of submerged hydrofoil, and CD is the dragcoefficient which is predicted by theoretical formula.

Consequently, the total resistance of full scale ship is as follows.

Rrs= C "- I PsVt + RFO!L (6)2

To evaluate the seakeeping performance, model tests were carried out inirregular headseas with significant wave heights of 1.5 and 2.5 meters. ITTCtwo-parameter wave spectrum is used for the generation of irregular waves. Shipmotion (pitch and heave), local acceleration for various locations and addedresistance were measured and compared.

2.3 Test results and sea trial

The resistance tests were carried out in the range of 20-46 knots while thedesign speed is 40 knots. The schematic diagram of resistance test is shown inFig. 3. The resistance dynamometer is moved up and down in order to measurethe resistance along the thrust line. The running attitude is measured by trimgauges installed at F. P. and A. P.

Fig. 4 shows the resistance-weight ratio of the model ship. There are nosignificant difference at the low speed range, but resistance-weight ratio isreduced by 18 %, from 0.12 to 0.1 at 40 knots, due to the attached hydrofoil.Moreover, the ship speed becomes higher, the difference becomes larger.

The effective power is shown in Fig. 5. The reduction of effective power byhydrofoil is around 400 PS at 40 knots and it corresponds to the increase of 2knots in speed.

To evaluate the seakeeping performance, model tests were carried out inirregular headseas with significant wave heights of 1.5 and 2.5 meters [5]. ITTC2 parameter wave spectrum is used for the generation of irregular waves. Testresults show that the acceleration of pitching moment is reduced around 15%,compared to conventional catamaran with same size.

This ship was successfully constructed in 1993 without any teething problem.One passive hydrofoil was successfully attached to the location of longitudinalcenter of gravity. The sea trial test shows that the maximum speed of this shipis 40 knots with 4,000 Kw main engine power.

Table 1 Principal dimensions of 350 Passenger Class Hydrofoil Catamaran

LOA (M) 40.0

LaP (M) 37.0

Breadth (m) 9.3

Depth (m) 3.5

Design 1.41

Full 1.55

CS 0.27

Cw 0.43

Wetted Surface Design 268.0Area (M2) Full 294.0

Trim (cm) Design -48.0-: by stern Full -47.0

The total resistances of the model with foil is defined as follows.

RTM= RHbRL + RFOIL (1)

The total resistance coefficient of the hull( CT,) is nondimensionalized as

follows,

o n RII&,L (2)C ' pSV '2

where S denotes the wetted surface area of hull.Residual resistance coefficient is derived as follows according to Froude

assumption ;

CR = C T.W-- CFW, (3)

where CTj, and CF.M are the total and frictional resistance coefficients of model

hull only. The total resistance coefficient of the full scale ship( CS) is

C7"= CR+ CFS+ C1 , (4)

where C.., is the correlation allowance. The correlation allowance (CA) is set tozero, which is proposed by 19th ITTC (report of the High-Speed marine Vehicles

7000

6000-r

5000w/o FOIL

4000

w/ FOIL3000

2000

1000 Fig. 5 Curves of effective

0 I power of 350 Passenger

20 25 30 35 40 45 Class HydrofoilKnots Catamaran

3. PAYLOAD 200 TON CLASS DOUBLE BOTTOM HYDROFOILCATAMARAN

3.1 Design concept

Design target is the payload 200 ton class car-ferry. This size of payload ismainly operated as a car-ferry, and conventionally catamaran or displacementtype mono hull forms are adopted. Although this ship is fairly large as a highspeed vehicle, it seems difficult operating at sea state 6 and satisfying theseakeeping requirement of passenger ship. To solve this problem and to improvethe seakeeping quality, it will be one of the solution to adopt the active controlsystem and to raise the hull by hydrofoil on the free-surface but the economicalefficiency becomes worse.

The concept of the Double Bottom Hydrofoil Catamaran is focused on twoaspects to improve the seakeeping quality. Firstly, the weight of hull issupported by the combined lift force of submerged hydrofoil, planing and thedisplacement. The seakeeping quality will be improved by not only reducing thesurface area on free-surface but also damping of hydrofoil. Secondly, the hull isdivided into two sections at each direction, longitudinal and transverse directions.As a conventional catamaran, the displacement is divided into two transversesections. As a results, transverse stability is satisfied and the broad deck area isattained. But this catamaran has some rooms for a longitudinal stability, i. e.,pitch movement in waves. To overcome this problem, the hull is also dividedinto longitudinal direction. This division will mainly contribute to theimprovement of seakeeping quality, because the hydrodynamic forces areconcentrated between station no. 3-5, i. e., near shoulder not the bow, which isobserved at the flow around ship in relatively large waves.

Tri - mTrimnguge gauge

-1 -------------- ---- T hru ýt Iline

'ResistanceDynamometer

Fig. 3 Schematic diagram of resistance test of 350 PassengerClass Hydrofoil Catamaran

, 0.15

0.14 w/o FOIL

0.12

0.10

ocoa Fig. 4 Curves ofresistance-weight

ratio of 3500.06 Passenger Class

0.04 ,Hydrofoil

20 25 30 35 40 45 Catamaran

Knots

Table 2 Principal dimensions of payload 200 ton classDouble Bottom Hydrofoil Catamaran

Design Load

LIp ( m ) 80.0B (im) 20.0D (m) 5.0A (ton) 660.0TF (iM) 4.0

TA (M) 3.0

Fore part Aft part

A (ton) 245.0 415.0CB 0.300 0.619

Cp 0.877 0.802Cw 0.699 0.845

3.2 Resistance test analysis

This high speed ship has 660 ton in displacement, 4 m in draft at F. P. and3 m at A. P. in design load. The photographs of model ship are shown in Fig.7.

t

Fig. 7 Photograph of model ship of payload 200 ton classDouble Bottom Hydrofoil Catamaran

The body plans and side profile of the hull form with this concept is shownin Fig. 6. The configuration of each section is similar to semi-planing hull withtransom stem. Table 2 shows the principal dimensions of payload 200 ton classDouble Bottom Hydrofoil Catamaran. The maximum speed of this ship is 40knots and the displacement of fore part supports 245 ton and aft part 415 ton,respectively. The aft part has 15 m parallel section in order to mount mainengine and propulsor. The fore and aft hull have basically same configurations.

forebody

VI/

a,..../- a

'V• II 15 I * / ,/ '151 1 2'

12 -

, , at IQ 3 6 5 . at 2

afterbody

-?J a! '? M" 1 "

Fig.6 Boy pan ad prfil ofpyla 00tn4ls

2.l, 21.5 -E 7LJ•Z 1L.....

2, 2 9 to 5 'z 1 3 3 I 1,5 IQ St 2

Fig. 6 Body plan and profile of payload 200 ton classDouble Bottom Hydrofoil Catamaran

The scale ratio of model ship is an 1/30 and the hull was manufactured ofurethane form to reduce the model weight and the hydrofoil is made ofaluminium.

The residual resistance coefficient is based on Froude methods.

CR = CTM - CFM (7)

CTM and CFM are the total and frictional resistance coefficients of a modelship. the total resistance coefficient (CTs) of a full scale ship is as follow.

CTS = CR + CFS + CA (8)

CFS is the frictional resistance coefficient of a full scale ship. The othersare same with of 350 passenger Hydrofoil Catamaran.

The resistance tests were carried out in the range of 20-44 knots in designload while the design speed is 40 knots. Fig. 8 shows the resistance-weight ratioof the model ship. At design speed, Fn=0.7, the resistance-weight value seemsgood as 0.085. But the submerged depth of hydrofoil is not so enough and hassome possibility of the appearance of cavitation. The optimization of this hullform will be considered in the near future.

2 -,- KS529Po I

o o

2 "F:1Fig. 8 Curve of resistance-weight

" Fig ratio of payload 200 ton

:1 •class Double Bottom01 Hydrofoil Catamaran

120 0.ý 30 .;O 10 ,0 0. W ' O .04FN

Fig. 9 shows the variation of trim angle and vertical displacement atmidship. The variation of vertical displacement due to ship's speed is small but

the trim angle shows the significant variation. The trim angle in the range ofFn>0.65 decreases and the bow raises. It may be due to the effect of hydrofoilattached in fore hull.

• 020 0 ° .4 O.M,• 0, , . W0 S. 0im .0 .?.* 0.o, 0,0 0. 7 o.M 0.60

.1

- , .00 0.4 0 .5 06 0.70" 0.00 0.030 0.40 0.50 s.6 1.70 0.60FN

Fig. 9 Curves of trim angle and vertical displacement of L C. G.of payload 200 ton class Double Bottom Hydrofoil Catamaran

The effective power from the measured results shows the peak value ofabout 37,000 PS near 30 knots. And decreases to 17,500 PS at 40 knots due tothe rise of hull by submerged hydrofoil.

The photographs of the model ship during resistance tests are shows in Fig.10. The ship starts to rise at 37 knots and fully raised at 40 knots. Theresistance performance after take-off seems good but before the take-off showssome rooms for optimization. The optimization of the hull will be considered inthe near future.

Fig. 10 Photographs of running ship model in 40 knotsof payload 200 ton class Double Bottom Hydrofoil Catamaran

4. PAYLOAD 500 AND 1,000 TON CLASS AIR CUSHION

CATAMARANS

4.1 The mission specification of the crafts

The payload is 500 tons, including about 800 passengers of each weighing 75kg with 50 kg luggage, and about 150-200 cars for the passenger-car ferry craft.

The maximum speed of this craft is about 50 knots, which may be suitablefor operating on domestic routes as well as international routes, e. g., fromMokpo to Cheju Island (Korea, 83 miles), Pusan (Korea) to Shimonoseki (Japan,120 miles), and Inchon (Korea) to San-Dong Peninsula (China, 240 miles).

Thus, the range of this craft is about 500-600 miles and the endurance ofthe design requirements will be 3-5 days.

The Yellow Sea, located between Korea and China, can be considered as aninner sea since the wave fetch is small. The route at the Korean Strait betweenKorea and Japan is also narrow. Therefore, both of the above routes can becharacterized by a short wave length and period. In addition, in order to keepthe operation of craft for over 280-300 days per year, the craft should be ableto operate on the sea state of 6 as the passenger ferry craft. Thus, the designsea condition is summarized as follows,

H113 = 3.2-4.0 m,

T (modal wave period) = 5.4-7.0 see,T (average wave length) = 45-76.5 m,V•,, (wind velocity)= 20-25 knots.

The JONSWAP(Joint North Sea Wave Project) spectrum is taken as thedesign wave spectrum to predict seakeeping quality for the operational sea region.

4.2 Design concepts

In order to maintain the good seakeeping quality for operating in an opensea with low density of payload (a large amount of passengers and cars as wellas containers), we take the SES craft with high length-cushion beam ratio, lowcushion-length ratio, widened sidewall, deep air cushion and medium cushionlift-weight ratio. Since the Froude number of this craft is not so high (0.7-0.9),the cushion lift-weight ratio(defined by $= Pcx Scl! , where Pc, Sc and W arecushion pressure, cushion area and all up weight of craft, respectively) was takento be 0.75-0.85. The main parameters of craft form are as follows :

Lc/Bc = 5.6-7.0 ; Pc/Lc = 12-14 HswILc > 0.06;•= 0.75-0.85 ; Psw/Bc = 0.2-0.25;

Where Bc Cushion beam length,Lc Cushion length,Psw Cushion depth.

Therefore, this craft can be described as the SES with thick sidewall or the

Air Cushion Catamaran. The background reasonings for the selection of such acraft are given in the sequel.

(1) The resistance performance of the designed craft was predicted to bethe best at this Fn(Froude Number). The craft is designed to operate at theFroude number of 0.7-0.85, since the drag curves for the models with variouscushion-pressure lift ratio will congregate at a small region, i. e., the cross pointof resistance with different side wall configuration will appear at Fn=0.72 -0.76.The friction resistance might be increased due to the thickened side wall, but theair cushion interference resistance will be reduced. The concrete ratio will bedetermined by the model test.

(2) Because the drag peak of the ACC is not very prominent, the craft issupposed to have good low-speed and medium-speed performance, even when thecraft is operating on cushion with only one propulsion engine, just likeconventional ships.

(3) The craft has the good transverse stability, and is safe in waves. Thebuoyancy of sidewall will reduce the cushion pressure fluctuation of the craft inwaves, improving the sea-keeping quality and, reducing the wave pumping andmotion pumping effect. The heave motion characteristics will be improved tosome extents.

(4) The passenger, car cabin and garage can be arranged in the craftthrough the full length of craft with bow and stern exits (entrance) because theengine and lift fan can be located in the sidewall.

(5) Since the craft has higher wetted deck and small draft due to thethickened and deepened sidewall, the force acting on skirt will be reduced.Therefore, the skirt life and repair condition will be improved.

(6) The craft will be less sensitive to the overload, because the drag curve atsuch region of Fn does not have prominent peaks. With the same reason, thecra-ft will be less sensitive to the damage of bow and stern skirts. rrherefore, thecraft is more reliable.

4.3 Lift system and skirts

In order to reduce the noise level of passenger cabin due to the cobblestoneeffect at high speed and in short waves, to improve the seakeeping quality and toreduce the mechanical malfunction, the followings are considered.

(1) rphe bag cushion ratio of bow skirt is set to one, e. g., the air of bagwil] be supplied directly from the cushion room so that the bow fan is notnecessary.

(2) We take the bag and finger-type bow skirt and triple-loop type sternskirt to improve the seakeeping quality. The air in loop will be supplied by twofans located at stern and driven by the hydraulic motors, thus the loop cushionpressure ratio can be adjusted according to the condition of craft speed/coursedirection and waves.

(3) Trhe six sets of centrifugal fan are to be located in the two sidewalls,and driven directly by two diesel engines. The main particulars of the fans areas follows:

Total air flow (Q) : 445 m 3/secSpeed of impeller : 1700 rpmDiameter of impeller : 1.66 mMax. tangency speed of impeller : about 148 m/sec

Max. pressure of fan : 1,300 kgf/ m 2 (12,700 Pa).

4.4 Principal dimensions

The main particulars of the passenger car ferry ACC craft are tabulated inTable 3.

Table 3 Principal dimensions of payload 500 ton classAir Cushion Catamaran

Aluminium alloy Steel hull

hull structure structureLm (max length, m) 92Bm (max width, m) 23Lc (cushion length, m) 84Bc (cushion beam, m) 14 -

Hsw (sidewall depth, m) 5.46AUW (all up weight, ton) 1,670

500 334Wp (payload, ton) (800 passengers (800 passenger

and 150-200 cars) and 100-150 cars)

Lift engine Two sets of marine dieselIIMTU 16V595-TE 70

Lift fans ' 6 sets of centrifugal fanswith a diameter of 1.66m

Total output of lift engine(kw) 10,800Two KaMeWa waterjet

propulsion system size 180 S11Two sets of marine gas turbinePropulsion engine I _TU- LM2500

Total output of engine (kw) 41,600Max. ship speed (knots) 50Initial static transverse stability 9height of craft on cushion h (m)h/Bc 0.68

The craft can be operated in sea state 6 with the significant wave height 3.6m and the modal wave period of 6 seconds, the vertical acceleration of the shipat LCG is estimated to be 0.112 g (rms), which implies the seasickness of

passenger is about 10% at such condition during 2 hours operation time by IMOrequirement.

4.5 General arrangement of the craft

General arrangement of the craft is shown in Fig. 11. Cars will beaccommodated in a garage for 150-200 cars on the wetted deck. It might bearranged with 18 lines and 11 rows. Since the height of the garage is about 3.5m, it's possible to accommodate some buses, coaches, and trucks with larger size.

GENERAL A4,RRANGEMENT (S 1/400)

7

Fig. 11 General arrangement of payload 500 ton classAir Cushion Catamaran

There are bow and stern ramps equipped at the garage to facilitate the raillon/off operation of the cars. The width of both/stern ramp is about 10 m.

The passenger cabin of economy class is to be arranged on the upper deckfor about 700 seats of 21 seats in each row. This cabin will be divided into twoparts, i. e. forward and rear cabin. Some kiosk, buffet, bar, storage house, andtoilet can be arranged between two passenger cabins and about 100 passengerseats of VIP class are located on the weather deck.

Passenger's luggage can be stored at the upper deck behind the passengercabin. Some cargo holds, refrigerators, and air condition equipments is arrangedbetween the funnels.

Two waterJet propulsors are installed at the rear part of each side walldriven by two marine gas turbines. Therefore, the machinery bay are adjacent tothe waterjet pump bay.

The lift fans are installed at the middle of each sidewall, driven directly bythe marine diesel engine. In order to save the weight and area, two funnels arelocated at the both sides of the craft. The inlet of fresh air for gas turbine andthe outlet of exhausted gas for gas turbines and diesel engines are designed toconcentrate into a compact funnel at the both sides above the weather deck.

The diesel engines are mounted in each sidewall separated from the fanroom so as to keep the engine room dry and to feed enough of fresh air for thediesels.

Two hydraulic pumps for driving the hydraulic motor, and the stern fans,are to be driven by two diesels with about 330 kw max. output for each. Thehydraulic motors can drive stern fans directly so as to control the stern loopcushion pressure ratio to meet the requirements of seakeeping quality.

4.6 Model test results

The FRP model was manufactured in the scale 1:25 and the model flexibleskirts are made of varnished cloth of 0.1 mm. Three fans arc equipped forcushion pressure in the model and the model was towed with the three degree offreedom: trim, heeling and heave. All of experimental investigation in this paperwere performed at Krylov Shipbuilding Research Institute of Russia.

4.6.1 Resistance in calm water

The resistance in calm water was measured behind the aerodynamic screenthat was fixed on the towing carriage in front of the model.

Three value of cushion lift ratio in calm water were tested, the cushionpressure could be adjusted by changing the low tip of both bow and stern seals.The test results can be found in Fig. 12. From this test, the cushion pressureratio for the passenger car ACC will be taken to be 0.85.

Three different air-flow rates were taken to estimate the influence of flowrate Q on the craft drag at various craft speeds. Fig. 13 shows the model dragversus speed with various lift cushion air-flow rate of the model in calm water.

The resistance becomes smaller if the flow rate increases. Based on theseresults, the estimation of air-flow rate influence on the total power for lifting andpropulsion was made for full scale ship at the speed of 50 knots. The fans andpropulsion efficiency were taken to be a constant equal to 0.6.

Table 4 Comparison of delivered power at various air flow rates of payload 500ton class Air Cushion Catamaran

Q (m/sec) DHP DHP DHP(Cushion Fan) (Resistance) (Total) 0HP/weight

250 6,800 50,800 57,600 34.5360 9,600 48,900 58,500 35.0500 13,400 48,000 61,400 36.8

From the above table, it is likely that the optimum air-flow rate for cushionpressure is in the range of 250-360 m 3/sec.

0.09

RTI 0.060.08 -0.08 0.7 Q=250(m'/sec)

0.07 Q=360(m',ls=c)---0.75

0.05 Q-5OO(m'/s=)

0.06

0.05

0.04

0.03 0.05 '35 40 45 50 55 45 50 55

Vs (knots) Vs (knots)

Fig. 12 Model drag versus speed Fig. 13 Model drag versus speedwith three different with various lift cushioncushion lift ratio air flow rateof payload 500 ton class of payload 500 ton classAir Cushion Catamaran Air Cushion Catamaran

The influence of longitudinal position of center of gravity can be found inFig. 14. It is expected that the optimum position for the LCG at 50 knots was4.60-4.62 Station with the point of view of minimum craft drag in calm water.But this figure also shows that the optimum position of LCG over 50 knots is4.55 station, a little behind comparing to the location at 50 knots.

Resistance tests for two other weight conditions were performed, as shown inFig. 15. It is interesting that all of resistance are crossing at around 58 knots.

The resistance characteristics of this craft in calm water is excellent and themaximum speed with two sets of MTU-LM2500 (total output 41,600 Kw) willmaintain 56 knots with the propulsive efficiency (q) of 0.65.

0.060

0.0A0.058

0.0568

0.054

0.052

Fig. 14 Model drag versus speed

0.050 ,with various LCG of the model4,.3 4.4 ,.5 4.6 47 4. of payload 500 ton class

St. No Air Cushion Catamaran

0.06 /

0.05

0.04,"., •,= i670ton

------ - --- - .1550toEn

0.03 ..... ..------- A t3 5o

Fig. 15 Model drag versus speed

0.02 _0 for three loading conditions20 o30 •o 0 60 70 of payload 500 ton class

Vs (knots) Air Cushion Catamaran

4.6.2 Seakeeping characteristics

The experimental investigation on seakeeping quality of the craft were alsocarried out in towing tank. The tests were conducted in head regular waves tomeasure the added drag in waves and the pitch and heave motion along with thevertical accelerations at bow and LCG. The added resistances with the waveheight 2 , 3 and 4 meters are shown in Fig. 16. The added resistances weremeasured with the air-flow rate 625 ;n3/sec, relatively higher than the optimum

air-flow rate in calm water (360 m 3/sec). Comparing the resistance in calmwater, it is considered that the added resistance in head waves is quite large -about 50 % at wave height 3 meters with the speed of 35 knots - so that thespeed drop in waves will be a serious problem. It is expected to make moreefforts to develop the hull and flexible skirt configuration.

0.050 Q.500mt/sc

0.045-----------3 5bw-Sm. X.w.l- k-77.5m

0.040

0.035

0.030 ,

0.025 /

0.= -Fig. 16 Added resistance of model0.015 in regular head waves

of payload 500 ton class0.010 Air Cushion Catamaran20 30 40 50

VS iknots)

The peak acceleration values at LCG in wave height 2, 3 and 4 meters areshown in Fig. 17. The maximum peak acceleration value is around +0.3-0.4 g,where g denotes the gravitational acceleration. The mean acceleration of LCG(rms) is estimated 0.2 g. Although it is rather higher than initially estimatedvalue, the seakeeping characteristics in sea state 6 is still satisfied. The bettercomfortability and seakeeping quality can be assured by using the ride controlsystem.

~*' f h.=2 X=55bm F h=An ;'=77.5m

0 0

0.0r • ";0.2

S kh.=3. kX65m

04

0.3

0.2o Fig. 17 Peak acceleration of model0.0 V, ft.) at LCG in regular head waves

.oX0 of payload 500 ton class0.2 ----------------- Air Cushion Catamaran-0.3

,o4

4.6.3 Self-propulsion test

The suitable position and length of skeg also can be determined from thetests to prevent the air injection into the waterjet pump in waves. From thetest result, it is estimated that the propulsive coefficients at design speed is equalto 0.65 by utilizing a pump with efficiency of 0.9.

4.7 Feasibility study on the payload 1,000 ton class ACC

Because the type of this ship is nearly the same as the ACC with payload of500 ton described previously in this paper, the feasibility study on this ship isbriefly discussed.

The payload of this cargo ship is 1,000 ton, i. e., freight capacity will beequivalent of 150 TEU containers.

The sea state 6 is the design sea state for Inchon(Pusan) - Shanghai routeto assure the operational rate higher than 80% for a whole year(292 day/year).

Since the Froude number of this ship is 0.75-0.8, (Vs=45-50 knots), theair cushion catamaran with -- 0.7 is the good choice. The 500 ton payloadhigh-speed passenger-car air cushion catamaran is the prototype, which is simplyenlarged one. The ships have the same main parameters.

The containers (14 ton, L xB xH=40' x8' x9'=12.2 m x2.44 m x2.74 m)are designed to arrange at the middle of ship, with 4-5 rows, 8-9 lines, and 2tiers, therefore, the total number of containers will be 4x 8 x2 or 5 X9 x 2, i. e.,

. L= 12.2X (4-5)+lx(3-4)=51.8-65m

Z B=2.44x(8-9)=19.52--21.96 m

The space of 25-30 m long is needed for main engine and waterjetpropulsion system at stern part and the space of 25 m long is needed on upperstructure for arranging the work and living quarters. Then the overall length ofship for general arrangement will be Lm,,, i l15m.

For the maximum ship width, the width of containers (CEB) and the sparespace on the upper deck should be considered. Then the max width will be

Bý., ý 22+6= 25.5-28m.The lift engines, lift fans, some working space and living quarters are

arranged on the wetted deck. The fuel, oil and fresh water tanks are located inthe both side walls.

Similar to the prototype (Payload 500ton class), the main parameters of thisship are Lc/Bc = 7.0, Hw/Lc=0.065.

Payload Wp is 1,000ton and we assume Jl Wp2-30%AUW.

Then the displacement is 3,400 ton, the principal dimensions areL = 119 m, B = 28 m, Hw = 6.9 m

Lc = 106 m, Bc = 17.7 m, Sc = Lc XBc = 1,876 m 2

= Sc XPc/AUW = 0.7 -0.75 (about 0.73)

Pc = 3,400,000 x 0.73 /1,876 = 1.323 kgf/r M2 = 12,979 paPcILc = 12.48 kgf/ M3

It's obvious that the principal dimension of ship can meet the bothrequirement of general arrangement and performance of the ship.

For the flow rate and pressure for cushion room, lift fans and engines aredetermined.

Since the ship is enlarged, it's expected that the nondimensionalized flowrate-Q can be reduced, then

Q=0.0025, Q=Q- Sc (p,=0.124 kgf/m 3, air density)-Pa

thus, Q=682.0m 3 /sec.The estimated resistance of this ship is given in Table 5. All of parameters

for the estimation are the same as the payload 500 ton class. The totalresistance and delivered power of this craft are 205,000 kgf and 74,500 Kw at 50knots in calm water with the propulsive efficiency ( ;r) of 0.65.

Table 5 Estimation of resistance of payload 1,000 ton class ACC

V (m/sec) 13.03 15.19 _}18.25 20.28 22.8 24.6 30.4" (knots) J 25.35 29.55 35.5 39.45 44.35 47.85 59.14

Fn 0.404 0.471 0.566 0.629 0.707 0.763 0,943I 0.005318 r 007

0.0232 0.025 0.0323 0.0402 0.0476 0.0518 0.0672

p IzR (W 78,880 1185,000 11o9,8201 136,680o1181,840 1176,12o285oR•,,.,t = E.R. 1.1 i I,

(including the drag of 86,768 93,500 120,802f 150.348 178.024 193.732 251.328

appendage)(kgf)l i ]EPS= R (KV U 11,000 13,900 21,600 29,900 39,8001 46,700 54,900

BHP = EPS (KM 17,000 21,400 33,300 46,000 61,200 I 71,900 84,500; -0.65 _ i I

For the cargo SES of 1,000 ton payload, the designing sea conditions are

H113 = 4.5 m,

5. PAYLOAD 1,000 TON CLASS SUPER SLENDER MONO HULL

5.1 Design concept

Design target is payload 1,000 ton class container or cargo ship. Based onthe payload, mono hull type has better efficiency by means of reducing hullweight and the total resistance than catamaran, SES and hydrofoil ships.Normally, the total resistance in constant ship speed is proportional to thedisplacement, while the conventional high-speed vehicle has almost sameresistance-weight ratio. The displacement type hull form has over 0.4 as apayload-displacement ratio, while conventional catamaran, SES and hydrofoil shiphave the range of 0.25-0.33 for payload-displacement ratio. Thus, thepayload-displacement ratio is set to 0.4 and the displacement is determined to be2,500 ton. The length-breadth ratio and block coefficient (CB1) is set to 10 and0.58, respectively. Thus, length, breadth and draft are 120, 12 and 3m,respectively. The midship section coefficient (Cm) is set to 0.8, and then,prismatic coefficient (Cp) is 0.725.

Because this ship will be operated as a container or cargo ship, therequirements for seakeeping quality are not so severe but the wave resistanceperformance is very important in order to have a good transport efficiency. Thedesign speed is set to 50 knots and mono hull with super slender submerged bowis adopted in order to reduce the wave resistance. rrhe slender bow is deeplysubmerged compared to conventional wave piercing type bow so that itcontributes to reduce the wave resistance. The hull configuration on the bow,upper part of the bow, is declined to backside, opposite direction to normalcontainer ship in order to reduce the added resistance in waves.

The principal dimension is shown in Table 6. The half load conditiondenotes the ship with payload 500 ton. The longitudinal center of gravity (LCG)and buoyancy (LCB) are set to same position because this ship is now onl theprimary design stage.

Z' "M ý M

Fig. 18 Photograph of ship model of payload 1,000 ton classSuper Slender Mono Hull

T 6.8 sec,- 72.2 mn,

V = 28 knots

Sea state 6.

By using JONSWAP spectrum, the vertical acceleration of the ship runningin waves can be estimated to be 0.14 g (rms) at 40 knots with the waveparameters( T 1=6.8 sec, H1/3=4.5 m, Vs=40 knots).

The estimated pitching angle of craft is0ý(RMVS)= 1.6' , 95,1/3 = 3.2' ,

0/0 = 4.060Therefore, the vertical displacement (Z) at bow due to the pitching angle is

as follows.

Z~ = L/ c tan 1 3 = 2.67 m2

Z(RMS) = 1.33 mZ111o = 3.38 in

The height of wetted deck at bow is around 10 mn. Therefore it's expectedthat the impact of wetted deck will not be occurred.

The rolling angle of craft in waves is estimated as follows

0, (RMS) =9.5'

Oa 1/3 = 17'

0j jjo = 21.4'Hence the estimated vertical displacement at both sides of craft due to the

rolling angle isZ 0 (RMS)= tan6 = 1.33m

2

Zj,: = 2.41 m

Z1 4/o = 3.09 m

It's found that the rolling angle is rather large, which cause the continuousleakage of cushion air at both sides, resulting in the uncomfortable motion andacceleration. It's due to the large rolling angle occurring at the shorter waves(or small wave frequency) at coastal area.

Therefore, in case of large SES running at coast line (or in sea closed tocoast line), the longitudinal motion (pitching angle or vertical acceleration at bow)will not be serious but the transverse motion (rolling and swaying) will beserious due to the shorter wave. For this reason, it's suggested that the bow (orbow/stern) fin with automatic control system should be mounted on the craft toimprove the seakeeping quality especially in beam sea.

Table 6 Principal dimensions of payload 1,000 ton classSuper Slender Mono Hull

_______________________________________ Half Load Full Load

(in)m 120-

B (in 12-

o min 6-Id (ton) 2,000 2,500

(in) 2.5 3.0TA (in 2.5 3.01-CB (m ) -10.22 -11.268WSA (m2) 1427 1576.3Ca 0.561 0.583

Cp 0.722 0.722 II w I 0.7 0.687

Cmj 0.777 0.08*Thrust Line 2.8 m above base line

5.2 Resistance test and analysis

The weight of full load condition is 2,500 ton and then the draft is 3 m.The model ship was manufactured of urethane foam to reduce the weight andscale ratio is 1/30. The photographs of ship model are shown in Fig. 18.

This ship will use the water jet propulsion system and the height of thrustline is presumed to be 2.5 m from the general arrangement of main engines andwater jet propulsion system.

'Tho resistance tests were carried out in the range of 20-52 knots in halfand fuUl load conditions while the design speed is 50 knots. The total andresidual resistance coefficients are shown in Fig. 19. The resistance coefficientsare monotonously decreased in the whole measured range. Little hollows areshown at Fn=0.35 and 0.65 at both load conditions and wave resistance isdecreased at high speed range of Fn>0.7.

Fig. 20 shows the resistance- weight ratio of the model ship. At FnO0.75,the resistance-weight value is 0.075. Compared to other hybrid hull form, thisship shows stable resistance characteristics at low speed operation.

Fig. 21 shows the variations of trim angle and vertical displacement atlongitudinal center of gravity. The variations of vertical displacement and trimangle are relatively small, because this ship has large length-breadth ratio, as aresult the trim angle varies within one degree. Moreover, the running attitudedoesn't show significant change even at high speed, over 45 knots (FnO0.7).

0.20 0.30 0.40 0.50 0.60 0.70 0.60

_0

IFig. 19 Curves of resistance

~coefficients of0'.20 0 .: ýa 0.' ;a 0.50 0 .o 'O 0. ;0 o.o payload 1,000 ton class

FN Super Slender Mono Hull

Din .a 0'0 T A

gJ

U C'

21 z 3.

D2 30 .5 - .. 0."1

F1 FN

Fig. 20 Curves of resistance-weight Fig. 21 Curves of trim angle and verticalratio of payload 1,000 ton displacement of L.C.G. of payload 1,000class Super Slender Mono Hull ton class Super Slender Mono Hull

Fig. 23 Photographs of running ship model in 50 knotsof payload 1,000 ton class Super Slender Mono Hull

6. CONCLUSION

The conceptual design study results are presented about a 350 passengerclass hydrofoil-catamaran, a payload 200 ton class double bottom catamaran, apayload 500 ton class car-ferry and two 1,000 ton class containers. Theconclusion through this study is given below.

350 passenger (Hydrofoil-Catamaran) :

(1) The hull form combined with the lifting forces by submerged passive foil isintroduced. Its resistance and seakeeping performances are validated andsuccessfully improved.

(2) From the model test results, it is concluded that not only hull form but alsothe location of submerged foil are important. Comparison with normalcatamaran, the resistance-weight ratio is reduced about 18% and it correspondto 2 knots speed up.

(3) The slender long bow and slamming bow are effective to reduce the added

resistance and local acceleration. Sea trial test showed the the resistance,seakeeping performance and running attitude were well predicted.

Payload 200 ton class car-ferry (Double Bottom Hydrofoil Catamaran)

(4) The design concept of this hull form is focused on the improvement of theseakeeping quality. The weight of hull is supported by the combined liftforce of submerged hydrofoil and the displacement. Futhermore, the hull isdivided to two sections at each direction, longitudinal and transversedirections.

(5) Measured results show that the peak value of effective power is around37,000 PS near 30 knots. This value decreases to 17,500 PS at 40 knots dueto the hull rise. The resistance performance after take-off seems good butthe ship before take-off mode shows some room for optimization.

° Fig. 22 Curves of effective power.of payload 1,000 ton class

. - Super Slender Mono Hull

SHIP SPEED IN KNOrS

'rhe effective power is shown in Fig. 22. It is seen that the effective power

linearly increases to the speed over 35 knots. 'rho total resistance and effectivepowers corresponding to 50 knots are as Table 7.

Table 7 Effective and delivered powers of payload 1,000 ton classSuper Slender Mono Hull

50kot aTM CTM OC , CFS3 CTS RTS EHP (sDHP50kos (Kg) × x10 3 x 103 x10 • xl101, (ton) (PS) (P,77r=0. 65!

Half Load 7.588 i 6.032 3.195 1.364 z4.559 i158.9 ! 54,4901 83,830Full Load 18.894 7.070 4.232 1.364 15.597!0195.1 166,895 102,915

The total resistance of ull scale ship is predicted to 195,000 kgf and the

residual resistance to 150,000 kgf. This residual resistance share much portioncompared to conventional catamaran hull knorm. Thisestal resistan stance can bereduced by hull form optimization. However, 50 knots in ship speed can be

attained by the 103,00 PS, less than any other hull forms, with the assumptionthat delivery efficiency is 0.65. It can be said that this hull f'orm has goodeconomic efficiency.

The photographs off running ship model are shown in Fig. 23. The large

wave crest is shown near shoulder where the water line becomes parallel. Thedevelopment near shoulder seems important Mor this ship.

Payload 500 ton class car-ferry (Air Cushion Catamaran)

(6) It can be said that the resistance characteristics in calm water of this craftare excellent. From the experimental results, the maximum speed with twosets of MTU-LM2500 will maintain 56 knots with the assumption that thepropulsive efficiency is 0.65.

(7) Although the mean acceleration of LCG (RMS) is rather higher than initialestimation, that value will be 0.2 g at sea state 6 and it is satisfactory.

Payload 1,000 ton class container (Air Cushion Catamaran) :

(8) By the estimation, the total resistance and delivered power of this craft at 50knots in calm water are 205,000 kgf and 74,500 Kw, respectively with theassumption that propulsive efficiency is 0.65.

(9) The vertical acceleration of the ship running in waves at 40 knots with thewave parameters (T1.=6.8 sec, h113=4.5 m, Vs=40 knots) is estimated to be0.14 g at LCG. But, the transverse motion of craft (rolling and swaying) willbe serious due to shorter wave exerting on the craft. For this reason, it'simportant that the bow fin with automatic control system should be mountedon the craft to improved the seakeeping quality especially in case of that inbeam sea.

Payload 1,000 ton class container (Super Slender Mono Hull)

(10) This ship will be operated as a container, the requirements of seakeepingquality are not severe but the resistance performance is very important inorder to have a good transport efficiency.

(11) The displacement type hull form has over 0.4 for the payload-displacementratio, while conventional catamaran or SES has the lower value. It can besaid that the super slender mono hull is better choice as a container.

It is considered that the construction of these hybrid concepts will bepossible, since all of main engine, equipment and hull structure can bemanufactured without any special difficulties.

ACKNOWLEDGEMENTS

This work was carried out under the sponsorship of the Ministry of Science& Technology program (Contract No. ND342). The development of a 350passenger class hydrofoil catamaran was supported by Daewoo Heavy ShipbuildingIndustries, Co. Ltd. Authors thanks to Prof. Liang Yun in Marine ResearchInstitute of China who studied the main frame of payload 500 and 1,000 tonclass ACC during his stay in KRISO.

REFERENCE S

[1] Ozawa, H., "A Concept Design Study of Techno-Superliner", Proceedings ofFirst International Conference of Fast Sea Transportation (FAST '91),Norway, pp. 199-208, 1991.

[21 Ozawa, H., "The Second Stage of TSL-A Program", Proceedings of the SecondInternational Conference on Fast Sea Transportation (FAST '93), pp. 35-46,Japan, 1993..

[3] Ogiwara, R. et al., "A Submerged Hull and Foil Hybrid Super-High SpeedLiner", Proceedings of the Second International Conference on Fast SeaTransportation (FAST '93), pp. 189-200, Japan, 1993.

[41 Brockett, T., "Minimum pressure envelops for modified NACA-66 sections withNACA a=0.8 camber and buships TYPE I and TYPE II sections", 1966.

[5] Kim, B. S. et al., "Improvement of Hydrodynamic Characteristics ofCatamaran with Hydrofoil", Proceedings of the Second InternationalConference on Fast Sea Transportation (FAST '93), Japan, pp. 631-642, 1993.

[6] Miyata, H., Tsuchiya, Y., Kanai, A., Manabe, T., "Development of a New-TypeHydrofoil Catamaran (4th report : Hydrofoil Interactions and HydrodynamicalProperties of a 4000 ton Type Ship)", Journal of the Society of NavalArchitects of Japan, Vol.168, pp. 1-7, 1990.

[7] Aleez, J. A., "The BES 16-A Spanish SES", Proceedings of HPMV92conference, U. S. A., 1992.

[8] Yun, L., Qiu Sheng-Hong, "Experimental Investigation on Air CushionCatamaran", Proceedings of First International Conference of Fast SeaTransportation (FAST '91), Norway, 1991.

[9] Yun, L., Zhu, J. Z., "Development of Medium Sized Sidewall HovercraftSeries 719", Proceedings of IV. PRAD'S Conference, Bulgaria, Oct., 1989.

[10] Hirano, M., "Research on Hydrodynamic Aspect of "Techno-Superliner-A",Proceedings of First International Conference of Fast Sea Transportation(FAST '91), Norway, 1991.

[ll Skomedal, N. G., "Scakeeping Evaluation of High Performance MarineVehicles", HPMV92 Conference Proceedings, USA, June 1992.

1121 Werenskiold, P., "High Speed Craft operational Performance and Limitation",3rd Conference on HSMC, Norway, Sept. 1992.

1131 Goubault, P., "The Integration of Operating Economics in the Early Designof High Speed Passenger Vessels ", Proceedings of HPMV'92, Virginia, U.S.A.,1992.

[14] Trillo, R. L., "Jane's High-speed Marine Craft", 1992-1993.[15] Shin, M. S., Choi, H. J., Yang, S. I., Yun, L., "Feasibility Study on a

Payload 500 and 1,000 Ton Class Air-Cushion Catamaran", Proceedings ofthe Third International conference on Fast Sea Transportation (FAST '95),Germany, pp. 1211-1222, 1995.

DEVELOPMENTS AND POTENTIAL IN OPEN SEA SWATH CONCEPTS

byProf. Apostolos Papanikolaou, Head of Ship Design Laboratory

National Technical University of Athens, GREECE




Developments and Potential inOpen Sea SWATH Concepts

A. D. Papanikolaou'National Technical University of Athens, GREECE

ABSTRACT

The present paper addresses the development of SWATH 2 type of ship designs for fast Open

Sea operations. The aspect of "Open Sea" is herein understood as a special quality

requirement on the seakeeping performance of the vehicles under consideration. The paper

attempts to cover the essentials of various design concepts deduced from the original SWATH

and related concepts. Insofar, Fast Displacement Catamarans and Semi-SWATHs and SWATH

Hybrids are within the following considerations. A common basis of the suggested twin-hull

designs is that they all aim at following the global concept of fast, reliable and safe sea

transportation, including the efficient cargo transfer from road/rail to ship with a minimum of

interruption of the cargo flow through the port. The vessel itself is considered to be a link in

the waterborne transportation chain, thus the proposed transportation system is acknowledging

the need for efficient interfaces between ship-port and port-road/rail. Finally, the potentiality of

the SWATH concept is reviewed in general, by taking reference to manifold other applications,

including navy ships, cruisers, workboats and oceanographic-research vessels.

' Professor, Head of Ship Design Laboratory, NTUA Athens. GREECE1 2 SWATH: Small Waterplane Area Twin Hull is synonym to SSC: Semi-Submerged Catamaran (MITSUI's brand-name)

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow. September 1996.

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1.INTRODUCTIONThe past decade has witnessed a rapid growth of interest in the development of Fast

(and Advanced) Marine Vehicles for various applications. Whereas, in the past, the design offast marine vehicles appeared to be of interest only to navy authorities, the most recentdevelopments seem to be driven mainly by commercial applications. Along these lines, inrecent years considerable efforts have been expended, world-wide, to develop new types offast cargo ships and to increase the share of waterborne transportation. In addition todevelopments in other countries with highly developed economies (e.g., USA and Japan)similar developments are currently underway in Europe, that might improve the conditions forthe necessary cohesion of various national economies within the European Community. It isevident, that in order to maintain or even increase the competitiveness of the Europeaneconomy as a whole, it is essential to improve the efficiency of the inter-European economyand transportation network as a whole, considering that a significant portion of the final priceof many products is paid for transportation (Zachsial, 1994).

The competitiveness of any transportation system, including Short Sea Shipping,depends on the price and quality of the offered services. The main factor characterising thequality of services is transportation time within a "door to door" delivery concept (Just InTime/lIT products). The inherent advantage of waterborne transportation, namely its lowenergy consumption per ton-kin suggests, that above a certain low limit for the service speed,the value of which is dependent on the transportation scenario, waterborne transportationappears to be a strong competitor to other transportation modes. Considering also theenvironmental impact of road-bound transport, the huge public flinds reserved for this specifictransportation mode and the frequent road traffic breakdown, especially during the summer-tourist season, it seems that a further increase of land transport will be in the near futurepractically impossible. Consequently, a reduction of the road-bound transport and cross-boarder traffic within Europe seems desirable. Thus, alternative transportation modes appearnecessary, even at higher cost.

The above economical and ecological aspects, encouraging the development of efficientand competitive Short Sea Shipping systems, are also supported by current developments inshipbuilding technology. Considering the time factor as one of the most important elements ofany transportation mode, it is evident that developments in Short Sea Shipping are interrelatedwith developments in Fast Sea Transportation and to technological breakthroughs inunconventional ship designs and in innovative port facilities. In the following, we address aparticular type of innovative ship design, namely SWATHs and SWATH Hybrids, that areconsidered to fulfil many of the above qualitative aspects of fast open sea carriers and enablethe integration within a global fast sea transportation system. As an example, an innovativeintegrated container carrier concept, namely SMLJCC3, is presented in the Appendix B. Therest of the present paper is organised as follows. Section 2 addresses the developments inSWATH Technology to date. Section 3 explains the fundamentals of SWATH concept and ofSWATH Hybrids, taking specific reference to their hydrodynamic performance, the hull formoptimisation and a generic computer-aided design procedure. Section 4 presents conclusionsabout the future potential of SWATH technology, considering merchant and militaryapplications.

' SMUCC: SWATH Mutidpurposc Container Cardrif

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WEGEMi' Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow, September 1996.

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2. RECENT SWATH DEVELOPMENTS

It is outside the scope of the present paper to outline the complete pre-history ofSWATH developments, since this has been covered extensively by others in the past (see, e.g.,Kennel, 1985 & 1992, Lang & Slogett, 1985, Mac Gregor, 1987, Betts, 1988). The originalidea of SWATH was first presented by A. Nelson (1905). Faust (1932), Creed (1946),Leopold (1967) and Lang (1971) carried the original concept idea of A. Nelson further andcontributed in several ways to the development of modem SWATH design concepts. Thesignificant change that has occurred in the past 25 years of SWATH history is the transitionfrom the scientific-development stage in the late sixties and early seventies, through theprototype hardware-engineering stage in the seventies, to the SWATH ship production stagein the eighties and the introduction of SWATH Hybrids in the nineties. The number of vesselsbuilt between 1969 and 1984 was merely seven (7). Since then, over four times as manySWATH ships have been built world-wide and this number seems significantly picking-up overthe last two years, considering the recent shipbuilding activity of various high-speed Semi-SWATHs and hybrids.

For the history record, the first two operational SWATHs were the offshore supportvessel DUPLUS (a medium-waterplane area SWATH hybrid of low speed), built in theNetherlands in 1969, and the U.S. Navy prototype KAIMALINO, built at the Pearl HarborNavy Shipyard in 1973. In the following years, MITSUI Shipb. Co. in Japan built a seriesSWATH vessels of varying size for manifold applications, starting with a small prototype(MARINE ACE) in 1977 and going to larger vessels in the late seventies and the 80ties,particularly passenger ships like SEAGULL I & II, oceanographic vessels like theKOTOZAKI, OHTORI and KAIYO and a variety of smaller pleasure boats. The largestSWATH representatives ever built, however, came from Finnish shipyards, namely the 130mLOA low speed cruiser RADISSON DIAMOND, built from steel, completed in 1992 byRAUMA Yards, and the 126.60m LOA high-speed passenger/car ferry STENA EXPLORER -HSS 1500, an all aluminum alloy construction, completed in 1995 by Finnyards. The lattership 4, that is supported by an innovative terminal facility enabling her fast loading-unloading, ischaracterised by her superior seakeeping performance in high sea states, combined with aservice speed in the range of 40 knots. The STENA EXPLORER is considered to represent,today, a world-wide "state of the art" of high-speed passenger ferry technology.

The characteristics of the most prominent SWATH ships built until today are tabulatedin Tables 1.1-1.7, grouped into seven categories according the ship's mission profile (seeAppendix). The list of ships cannot be exhaustive and several technical data are, for obviousreasons, not readily available to the public. However the given tables should contain sufficientinformation to allow comparisons with alternative designs. Finally, Table 1.8 contains thecharacteristics of several SWATH and SWATH Hybrid designs completed at the Ship DesignLaboratory of NTUA since 1989. From the above designs, only Supercat Haroula (GoutosLines, Piraeus) could be put into practice, so far, whereas SIMICA T is currently undernegotiation with local operators. The ferry Supercat Haroula5 , actually a medium speedSWATH hybrid with appreciable waterplane area, has a LOA of 80m, a full load displacement

The STENA EXPLOPER is actually a Semi-SWATH. The forward pat of her hull for-n is SWATH like, whereas the hull rear part follows thecharacteristics of a semi-displacement canamaran. enabling the accominzodation of Iwo 25.000 HP watetijets. per dernihull, and providing thevessel with some degree of dynamic lift for balancing the running trim at higher speeds.

With an installed horsepower of 2X6500 HP she will have a service speed of abt 21.0 knots

A. D. Papanikolaou. "Developments and Potential in Open Sea SWATH Concepts".WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow, September 1996.

3 08/09/96

of 2180 tons and a transport capacity of 1.500 passengers (summer) and 240 cars. She is oneof the largest all-steel twin-hull ships ever built world-wide and the first one of this type andsize built in Greece (Vernicos Yard).

2. THE SWATH CONCEPT AND HYBRIDS

The SWATH carrier design concept follows the strategic principle of "function-separation" and splits the function of the ship's hull into two main functions, namely the cargoor payload carrying function of the ship's superstructure, enabling easy loading-unloadingfrom the top or the side, and the buoyancy-weight supporting function of the ship's lowerpart, accommodating mostly the ship's machinery-propulsion unit and a variety of auxiliarysystems. (see, Fig. 1, acc. to S. Akagi, 1991). For achieving higher speeds with sufficient shipstability, assuming the concept offunction separation as a strategic principle to be followed forthe development of efficient fast marine transportation systems, it appears that the assumptionof a multi-hull configuration is a further inevitable consequence.

[lyto chi kmu.

[ I dTull o f ..l

5 s c-mi~ a -% t ri blujliv

Con ye Jljonn I

Ca- Sc'parmiionfl"Sppor

Cargo Casryi.g * Suppocing aFu"cI ion Suppontng Funcion Supporting FIicljouI

\'Vnre-picrcir:g F lull( Supp tiriig Fonth,

Fig. I Principle of Function Separation for High-Speed Cargo Carriers acc. to S. Akagi

From the fundamental point of view, SWATH ships are buoyantly supported twin hullvehicles with small waterplane area. Most of the buoyancy is provided by the submerged lowerhulls, the shape of which is generally cylindrical, but can vary sectionwise, when optimized fora specific operational profile (speed). The SWATH cross-deck structure, connecting the twodemihulls and carrying most of the ship's payload, is supported by thin streamlined struts,piercing the water surface. Most of the SWATH ships built today have used the "one strut perhull" concept, however a "twin strut per hull configuration" was also implemented successfullyin practice. In addition, though most strut configurations are exactly vertical, a "canted strut"concept was also considered in the past for smaller ships, improving significantly the ship'svertical motion behaviour.

A. D. Papanikolaou. "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow. September 1996.

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Fig. 2 Generic SWATH Geometry Features

Based on the unique hull form configuration and the related distribution of the ship'sdisplacement volume, the primary attributes of SWATH ships are, first, the superiorseakeeping performance and , at second, the low wave resistance at medium to high Froudenumbers. These attributes will be explained in more details in the following.

Other related concepts to SWATH, that we like to call SWATH Hybrids or Semi-SWATHs6, include variations of the global or local thickness of the struts, therefore indirectlyof the magnitude of the ship's waterplane area and the vertical distribution of buoyancy, thelocal shaping of the struts and their connection to the lower hulls up to the completedegeneration of strut and lower hull, locally, to a single form, and local variations of the lowerhull sections, especially in the ship's rear part, for the accommodation of waterjets and theprovision of additional dynamic lift at higher speeds. Finally, a deviation from the original twin-hull SWATH concept, but still with use of SWATH-like cross section shapes, leads to theSWASH 7 monohull and the 0' Neill SWATH-Trimaran concept.

After all, it seems very difficult, nowadays, to distinguish a modern fast displacementcatamaran design from the variety of representatives of the original SWATH concept.Designing a displacement type, twin-hull ship for good seakeeping and reduced waveresistance, for balancing the fundamental drawback of the increased frictional resistance of atwin-hull configuration, the SWATH type of hull form involving the placement of a significantpart of ship's buoyancy well below the free surface, seems natural and clearly justified byphysical reasoning. Independently, as will be shown later, application of modem hull formoptimization techniques lead to the same results, therefore modem twin-hull form designs willnaturally exhibit certain SWATH features, the extent of which will be determined by the setdesign constraints typical to each particular ship design.

'MWATH: Medium Waterplane Area T•in Hull. FDC: Fast Displacement CIatanaranSSWASH: Small Waterplane Area Single Hull

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts".WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow, September 1996.

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3.1 Transport Efficiency - Hydrodynamic Performance

In the past, many authors dealt with the hydrodynamic and transport efficiencyperformance of SWATH ships, especially in comparison to monohulls and other alternativedesign concepts (see, e.g., Eames, 1990, Kennel, 1985).

As far as the transport efficiency is concerned, defined herein, ace. to Eames, as

Do = 5.045 A [tons] Vo[knots]/Po[kW]where A is the full-load displacement, and P0 the shaft horse power required at maximumcalm-water speed V0 , the following chart (Fig. 3, ace. to Eames, 1980), developed in the lateseventies best on results of a NATO study on "New Technologies Applicable to the Design ofHigh Speed Surface Vessels" seems to be of permanent value to the international literature, tobe repeated herein for the sake of completeness. It should be pointed out, that the chart doesnot take into account the maximum attainable speed at sea, therefore the cited values ofefficiency for SWATH ships can be considered to increase by a certain percentage, against thecompetitor designs, based on the sea state conditions for a particular scenario. Also, the chartdoes not account for the payload efficiency, as percentage to the ship's displacement, what isgenerally changing the given trends significantly, based on the particular type of ship design,the used construction material and the employed machinery-propulsion system.

240 1CONVENTIONAL SHIPS 022 SUB-HUMP SEMI-PLANM SHIPS 0 FORECAST

20 0 PLANrNO CRAFT r CURRENT BEST20 ;I\ SWATH I P S Po a POWER REQUIREDIs STO ATTAIN SPEED

< SLENDER Vo IN CALM WATER£ 6

SURFACE EFFECTS SHIPS 0o 14 AIR CUSHICN VEHCLES"

.12 SES ALL L/B

U HYDROFOILO SWATH

00

uJ (9ACV

C_

4 SEMI - P LANNG 00

aLA 0 kt I- k 2,0i t 0 5 0 To kl8k

i E IPLANING 0 I' N"T 2 .30"1. O t 4I~ U Oi 2, k1 do*OtI , ý

2. "0o It b 2 0. 12•6 5. 2 26 : , 4•712.000 59 6 22 1 g 2:., Z 2

O1C 1.5 20 2.5 30 3.5 40 30.0019 ION 42 77 71I ± .4 2-4

VOLUMETRIC FROUDE NUMBER (Fpo)

Fig. 3 Forecast Trends of Transport Efficiency acc. to Eames (1980)

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow, September 1996.

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3.1.1 Resistance and Powering

Compared to a monohull of equal displacement, a SWATH ship tends to exhibit a calmwater speed penalty, owing to her larger wetted surface area, causing an increased frictionalresistance, and her shorter waterline length, placing the ship's operational Froude number at ahigher level. However, proper hull form shaping can alleviate the above drawbacks and giventhe superior propulsive efficiency of a SWATH hull form configuration (besides the inherentlygood seakeeping performance) it seems nowadays possible to develop SWATH like hull formsthat are competitive to alternative designs, including monohulls.

In the following, we address some efficient and reliable methods for the calculation ofthe wave resistance of SWATHs, in their original form, and of Fast Displacement Catamarans,covering the range of SWATH Hybrids. In doing so we tacitly assume, that the frictional andthe viscous-pressure part of resistance of slender hulls, as the demihulls of SWATHs and offast catamarans are, can be successfully approached by common semi-empirical methods(ITTC line with a form factor ace. to systematic experiments and semi-empirical formulas). Ofcourse, the problem of catamaran stem flow separation at higher speeds, needs to beconsidered separately, in connection with the arrangement of an optimal propulsion system. Inany case it can be assumed, due to the slenderness of the demihulls, that the uniformity of thepropeller onset flow of fast displacement catamarans, and especially of those having SWATH-like stern sections, will eventually contribute to a relatively high propulsive efficiencys.

It is well established that the determination of the wave resistance of symmetric slenderor thin twin hull vessels can be easily achieved by application of the classical theories ofMichell-Havelock (monohulls) and Strettenskii-Eggers (monohull in a canal and twin-hulls).They all lead to relatively simple formulas for the wave resistance, in terms of simple typecenterline or centerplane Kelvin source distributions, the strength of which is derivedimmediately from the hull form characteristics of the studied vessel. These methods considerthe effects of hull interaction on the catamaran wave resistance in an approximate way, namelyby superposition of the individual demihull's far-field wave pattern and thereafter byemployment of a modified KOCHIN function to calculate the catamaran's wave resistance.Eventually, there is a direct relation between the wave resistance and the ship's hull form,defined by the hull offsets. Extending this concept also to the frictional part of resistance, beingdirectly proportional to the local Reynolds number and the hull surface area, it is possible todeduce a direct functional relationship between the sum total of the wave and frictionalresistance9 and the ship's hull form offsets, leading to the formulation of a systematicoptimization procedure by Lagrange's multiplier method (see, Papanikolaou, A. andAndroulakakis, M., FAST'91, 1991). This method, that proves to be very efficient and fast,was applied successfully in the past to the design of several SWATHs and thin, but symmetric,catamarans and the theoretical predictions have been validated, in most cases, successfully bymodel experiments.

'Attention should be paid to the reduction of die propulsive efficiency at speeds, corresponding to extreme "humps" in the wave resistance curve.when the propeller is operating under a local wave "trough"'it is essential to include in the formulation of local form optimization problem, by Lagrange's multipliers method, the frictional resistance.because of the "ill-conditioning" of the coefficient matrix. to be inverued for the problem solution (see, Salvesen. N., Von Kerczek. E. H., et al,Trans. SNAME, Vol. 93, pp. 325-346, 1985).

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Whereas the above procedure is limited to symmetric catamaran hull forms only, a fairportion of existing and under development displacement catamarans have non-symmetricdemihull forms for manifold practical reasons, including the hydrodynamic performance in calmwater and in waves. The design of nonsymmetric catamaran hull forms has been addressed,until now, only by use of semiempirical methods and model experiments. We present herein anextension of the traditional wave resistance of Michell-Strettenskii for thin non-symmetricdemihull forms. The proposed method extends Michell's original approach by including, inaddition to the centerplane sources, a centerplane normal dipole distribution, the strength ofwhich is related to the asymmetry of the demihull form. It can be determined numerically bysolution of a properly formulated Hypersingular Integral Equation of first kind. Alternatively,the solution of the above integral equation can be approximated by an asymptotic expansion interms of the local hull geometry characteristics (see details of the complete theory inPapanikolaou et al., ONR Symp. 1996). This particular method, that is, at our knowledge, newin the international literature, has been applied systematically to a variety of standardized twinhull arrangements (non-symmetric demihull forms of WIGLEY or wallsided strut type).Therefrom, some important conclusions concerning the influence of the section asymmetry onthe wave resistance, and especially on the hull interaction resistance, can be deduced. Theimplementation of this procedure into the overall optimization scheme, introduced before, willeventually lead to innovative demihull forms of least wave resistance, depending on the speed,displacement and separation distance of the demihulls, specified by other design constraints.However, it remains to validate the obtained theoretical results for the nonsymmetric demihullforms by systematic model experiments.

For the validation of the above simplified methods, pertaining for thin demihull formshaving a sufficiently large separation distance, and for accounting more general twin-hullarrangements, we employed a full 3D panel source method, that is based on a completeanalytical-numerical solution to the well-known Neumann-Kelvin problem. This latter method,the computer algorithm of which has been recently completed at SDL-NTUA, is based on theevaluation of the 3D Green Function of the traveling source by use of Newman's methodology,as to the Double Integral term, whereas the Far Field disturbance term has been approached bythe suggested method of Baar and Price, considering Bessho's expansions in Neumann series.The developed 3D panel source approach has been validated successfully for a variety of hullforms, both monohulls and catamarans, as shown in the following example cases.

Finally, the validation of the above presented theoretical-numerical methods has beenestablished by systematic model experiments performed at the Marine HydrodynamicsLaboratory of NTUA and partly at the Towing Tank of VWS Berlin. The validation concerns avariety of standard Wigley twin-hull arrangements and several practical designs, developed atthe Ship Design Laboratory of NTUA, namely here two high speed SWATHs and two mediumto high speed displacement Catamarans. Some typical results of these comparative studies aregiven in the Appendix C.


8 08/09/96

3.1.2 Seakeeping

It is outside the scope of the present paper, to describe the theoretical methods used forthe seakeeping analysis of the addressed Fast Displacement Catamarans. Details of theemployed 3D, alternatively quasi 2D, panel source methods can be found in previouspublications of the of the author, listed in the references. We restrict herein ourselves into thedescription of the general methodology for the design of Fast Displacement Catamarans withoptimal seakeeping characteristics, considering that an original SWATH ship will naturallyflulfill several of the attributes, described in the following. The adopted methodology leads tospecific design requirements that can be incorporated as constraints on the hull geometry or asqualitative criteria within the formal optimization procedure for the ship's calm waterperformance, presented before.

The responses of a ship in a seaway are naturally determined by two basic aspects:

1. The ship characteristics: mainly the ship's mass, including the mass distribution, and hernatural periods in heave, pitch and roll.

2. The seaway characteristics: the amplitude and period of the exciting waves and theresulting wave exciting forces and moments.

Given the speed of the ship, and indirectly her mass1 0 , as well as the operationalenvironment (wave characteristics), the methodology for reducing the ship responses, bydesign, consists in measures to tune the values of the ship's natural periods, to be outside therange of possible resonance with the exciting waves, and to reduce the amplitudes of the waveexciting forces, e.g. by proper hull form shaping and favorable weight distribution to the extentpossible within the limits of design and operation of the vessel.

As to the tuning of the natural periods, it is well known that, besides the fine-tuningthrough motion damping devices (fins etc.), the only tool practically available to the designer isthe variation of the waterplane area and, to a certain limited degree", the variation of theship's underwater hull form determining the "added" mass and moment values.

The slenderness and thinness of the demihulls of Fast Displacement Catamarans and thegenerally small waterplane area will contribute, in general terms, to a shift of the naturalperiods in heave, pitch and roll to relatively high values, therefore outside the range ofresonance with short period waves, typical to many coastal areas 12. In addition, assuming ahigh forward speed, the vessels will always tend to operate "undercritical", especially in headseas, due to the effectively very small period of wave encounter. A typical representative ofthis type of ships, with excellent seakeeping characteristics especially in short seas, is theSWATH ship. However, Fast Displacement Catamaran hull forms and Hybrids, deviating fromthe original SWATH concept as to the smallness of the waterplane area and the underwaterhull form, will naturally exhibit worse seakeeping behavior, at the benefit of increased vertical

"It is tacitly assumed, that, at the stage of evaluation of the seakeeping performance, the displacement of the ship is fixed through the initialdesign procedure (for given payload capacity and specific design arrangements, speed and range, an estimation of the weights for the structure,machinery, outfitting and corsumables is possible)."The underwater ship hull form, especially of a fast ship, is commonly determined by low resistance aspects."We assume that Fast Displacement Catamnara will be mainly operating in coastal areas with short period seas. A typical example is the AegeanSea Archipelago with a typical year-round peak wave period of 5.0 sec.

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow, September 1996.9 08/09/96

plane stability. The main design tools for the tuning of the natural periods, to be positionedoutside the range of the possible wave encounter periods, are:

* For the roll natural period. limitation of the transverse metacentric height GMTthrough the smallest possible13 separation distance of the demihulls and the positioning ofheavy loads as high as possible. Maximization of the effective roll radius of gyration by propermass distribution and shaping of the underwater hull form for increased added mass andmoment coefficients. Both latter measures are very difficult to be implemented in practice, dueto technical reasons or because of the contradiction to other requirements.

e For the naturalperiods in heave andpitch: a fine tuning is possible by limitation ofthe waterplane area to the extent possible. A concentration of the waterplane area around thecenter of flotation, leading to short and beamy waterlines, results to a relatively smalllongitudinal metacentric height GMI and relatively high pitch eigenperiod, however at theexpense of increased wave resistance, especially at higher Froude numbers. In any case, a largefast catamaran ship with appreciable mass and with small to medium waterplane area willcontribute through her mass to reasonable values for the heave and pitch natural periods.

As to the second factor influencing the seakeeping behavior of a ship, namely themagnitude of the exciting forces and moments, it is well established that ships with bulb-likecross sections will experience reduced wave exciting forces and moments, at least at the so-called "wave excitationless frequencies"' 14. Again the SWATH type of ship is the bestrepresentative of the Fast Displacement Catamaran family fulfilling the above criteria for a hullform with least possible wave excitation impact.

In evaluating the seakeeping behavior of twin hull vessels alternative quasi 2D (strip orslender body theory approach) and more strict 3D panel methods can be employed. Due to theslenderness of the demihulls of Fast Displacement Catamarans, including SWATHs andHybrids, the analysis of the seakeeping behavior in head seas can be easily accomplished byeither approach. However, the oblique and beam seas condition requires special care, due tostrong interactions between the incident wave and the two demihulls as well as due to three-dimensional effects at the ends. These cases can be successfully approached by 3D panelmethod, accounting for the forward speed effects in the sense of a slender body theory [14].For SWATH ships, additional attention should be paid to the following seas case, when athigh forward speed, and the vertical plane instabilities due to the action of the so-called Munkmoments. Also, the inclusion of the stabilizing fins and the estimation of the estimation of theviscous damping requires additional fine-tuning of the employed computer algorithms.However, these problems are considered solved in a satisfactory way by a variety ofresearchers, including related work at the Ship Design Laboratory of NTUA, therefore anydetails can be omitted herein fou the sake of brevity. Some typical results of seakeeping studiesrelated to SWATH ship designs are given in the Appendix C.

"Limit set by the wave interaction resistance.14see, e.g., Motorm. S.. Koyanma. T., Proc. 6' S)mposiurn on Naval Hydrodynamics, 1966.

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow, September 1996.

10 08/09/96

3.2 Hull Form Optimization

The optimal hull form development of Fast Marine Vehicles is of particular interest,both from the hydrodynamic and design point of view, but also from the construction,operational and eventually economic point of view. The relatively high ship velocity requiresincreased effort as to the minimization of the ship's resistance, particularly the wave resistance,as well as to the seakeeping behavior of ship under consideration. Stability proves to be asevere design constraint for fast ships in general, even in the intact case. Considering inaddition the damage stability of fast ships after grounding or collision, it seems that certainadvantages of the monohull concept against the multihulls, particularly the smaller wettedsurface and structural weight for equal displacement, will have to be reconsidered in the future.Therefore, an increased interest into the design of Fast Multi-Hull Vessels can be expected inthe future.

The demihull form of the addressed twin hull vessels can be assumed, by commondesign sense, to be slender, thus changing slowly in the longitudinal direction, but else being ofarbitrary shape. Thus we should consider herein symmetric or non-symmetric demihullsections, but in general arbitrarily shaped thin or slender hull forms, varying else arbitrarily inboth the transverse and in the vertical direction. Therefore we address practically all thinkabledisplacement CATAMARAN hull forms, including SWATHs'5 and Hybrids' 6.

The present paper is focusing on the calm water performance of Fast DisplacementCatamarans and their hull form optimization with respect to least horsepower requirement,assuming the desired vessel's speed and displacement' 7 known and considering variousgeometric parameters set by design or by other operational constraints. The employedoptimization procedure consists of two basic stages, iamely, in the first phase a globalprocedure leading to the main dimensions and integral form and weight characteristics of theship, whereas in the second phase a local form optimization is performed leading to the exactgeometric characteristics and the final hull form of the vessel under consideration. The overallgoal of the above optimization process is to generate, with the least possible computational andexperimental effort, seakind catamaran hull forms with low weight and resistancecharacteristics. From the naval architectural point of view these requirements arecontradictory, because a seakind catamaran requires moderate stiffness (low to moderatemetacentric height), thus small separation distance between the demihulls, what has theadditional positive effect of low structural weight, whereas the low resistance (and especially,for fast catamarans, low wave resistance) requirement, that indirectly calls for reducedmachinery and fuel weight, suggests a large separation distance for the demihulls, for avoidingthe negative interference effects on resistance, that can easily triple the single demihull'sresistance (see, Turner/Taplin, Proc. SNAME Ann. Conf., 1968). Therefore, a formaloptimization procedure for fast catamarans should be looking for twin hull arrangementsexhibiting the least possible separation distance for the demihulls, thus disposing reduced

"SWATH: Small Waterplane Area Twin Hull is synonym toSSC: Sen•-Submerged Catamaran (MITSUI's Co. brand-name)

"Hybrids: herein understood as a mixture of. conventional displacement catamaran hull form with a SWATH: Medium Waterplace Area TwinHulls (MWATHs), Fast Displacement Catamaran (FDCs, FBM Marine Ltd brand-name), etr.'It is more correct to assume, instead of the displacement, the payload capacity given by the owner's requirements. However, an optimizationwith respect to the least horsepower requirement, as suggested herein, assuming the displacement and the speed of operation fixed, leadseventually for fast displacement catanmarans to ship designs with maximum payload capacity.

A. D. Papanikolaou. "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow, September 1996.

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structural weight and moderate stiffhess in roll direction, without compromising on theincrease of the sum total of the demihulls' single resistance. Instead of, it is expected thatthrough proper shaping of demnihulls the interference resistance can be tuned to be, for thespeed range of interest, small and even below zero. Because of the multiple parametersinvolved, it seems very difficult, if not impossible, considering reasonable effort, to address theproblem of hydrodynamic optimization offast displacement catamarans only by systematicmodel experiments. Therefore, a computer-aided hull form design procedure, as explained inthe following, seems essential for the concept and initial hull form development, that can belater on verified by a limited number of model tests.

3.3 Design Methodology

Due to the innovative character of the design of Fast Displacement Catamarans,including SWATHs and Hybrids, it is essential to set-up a specific computer-aided designprocedure, allowing the convenient and reliable repeat of the necessary steps following thedesign spiral. The overall design methodology and optimization procedure consists of severalindependent but interacting modules, namely (see Flowchart, Fig. 4, [13])

1. The Conceptual Design Synthesis Program, consisting of simplified algorithms and databases of previous designs. It allows the generic design of a standardized ship, assuming theinitial owner's requirements known. It might call, optionally, the hull geometry module (hull-form generator and shiplines fairing under shape and integral constraints).

2. The technoeconomic Parametric Economic Evaluation module, that is employing theConceptual Design Synthesis Program as a pre-processor (evaluation of shipbuilding cost,operational cost, Required Freight Rate RFR or Net Present Value NPV, [9]).

3. The Hydrodynamic Optimization module consisting of algorithms for the HydrodynamicAnalysis (evaluation of calm water resistance and of seakeeping [11], [12]) and for the formalHull Form Optimization (global NLP optimization by the so-called Reduced Gradient Methodand local form optimization by LAGRANGE method, [12])

4. The Preliminary Design Synthesis Program consisting of various software packages for thehandling of the hull geometry and preparation of common naval architectural drawings (shiplines and general arrangements'), the powering, the seakeeping and the structural design (see[13] for details).

ILAUTOCAD-h. AUToSHIprh


12 08/09/96

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Fig. 4 Multi-stage optimization and global design procedure for

SWATHS and Fast Displacement Catamarans


13 08/09/96

4. FUTURE SWATH POTENTIAL

Having assessed the basic characteristics, namely advantages and drawbacks, ofSWATH ships and related concepts3 9, it is possible to outline possible future developments,especially in those fields of application, where the SWATH ship seems to have a clearadvantage over alternative design concepts. These developments will be at the authors opinionthe following:

1. Passengers Ferries

Based on the inherent advantage of SWATH ships in their seakeeping performance, especiallyin short period seaways, typical to many coastal areas around the world, there should be a cleardemand for further development of SWATH passenger vessels with a carrying capacity of upto abt 600 passengers and a service speed of between 25 and up to abt 32 knots. The practicalelimination of seasickness and the provision of regular service even in poor weather conditions,without serious effect on speed, will be the determining factors for the employment of thistype of SWATH ships (and to a certain degree of SWATH Hybrids).

2. Cruise Ships

Again, based on the inherent advantage of SWATH ships in seakeeping performance and inaddition considering the spaciously available deck area and volume of a twin hullconfiguration, as compared to a monohull of comparable size, there should be a clear demandfor further development of SWATH cruise vessels of varying size and type of cruise, startingfrom a pleasure boat of small length of abt 15-20 m with appreciable relative to the size topspeed of abt 20 knots and going to large scale cruisers, over the size of RADISSON'sDIAMOND (LOA over 130 m), then at a relatively low top speed of up to abt 20 knots,determined by the cruising scenario. The practical elimination of seasickness and the provisionof a stable platform for staying, even in poor weather conditions, the spacious livingarrangements for passengers, in best located outside cabins and the increased safety againstcapsizing, will be possibly the major factors for the employment of this type of SWATH ships(and to a certain degree of SWATH Hybrids).

3. Passenger/Car Ferries

Compared to the pure passenger ships, the combined passenger/car ferry SWATH concept ismore difficult to implement successfully in practice, despite good overall relation betweenavailable displacement/ volume and payload weight/space requirements. This is mainly due tothe inherent sensitivity of the original SWATH concept (when with a appreciably smallwaterplane area) against significant cargo weight changes, occurring in practice during the carloading/unloading procedure. However, deviating slightly or even more from the originalSWATH concept by accepting a fuller waterplane, especially in the ship's rear part, it ispossible to design SWATH hybrid hull forms with sufficient vertical (and rotational) stiffnessfor a satisfactory loading procedure. This design measure can be further supported, in case of

'9 Includes SWATH Hybrids, SemkiSWATHs and FDCs (Fast Displacement Catamarans)

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow. September 1996.

14 08/09/96

need, by external-operational means, namely pre-loaded mooring devices and/or efficientballast systems. Again, the inherent seakeeping advantage of SWATH ships, the spaciouslyavailable deck area and volume of a twin hull configuration, as compared to a monohull ofcomparable size, and the high degree of safety (intact and damage stability) should contributeto a clear demand for further development of SWATH car ferries of varying size, starting frommedium size coasters with a length of abt 50 m and a transport capacity of abt 600-800passengers and 60-80 cars and a service speed of abt 25-30 knots and going to large scaleferries, possibly even over the size of STENA's HSS 1500 (LOA over 130 m), then with atransport capacity of about 1500-2500 passengers and 300-500 cars and a top speed of up toabt 45 knots, determined by the operational scenario and the limiting size of existingpropulsion units (gas turbines and waterdets). The practical elimination of seasickness for thetravelers, the provision of a spacious, stable and safe platform for passengers and crew, withlow level of noise and vibrations, the reliability of service even at poor weather conditions andthe high speed of overall transportation, including the fast loading and unloading, will be thedetermining factors for the further developments of this type of SWATH hybrids. Whereashigh-speed SWATHs will be inherently connected with light material constructions and relatedtechnological problems, especially for the larger sizes, it seems that low to medium speedSWATH hybrids, built from steel, will be able to claim also a market share, especially ifconventional Ro-Ro passenger ferries continue to be burdened with stricter damage stabilityregulations leading to compartmentation of the car deck, an increased structural weight anddecrease of the operational efficiency.

4. Pleasure - Crew - Fishing Boats

Again, based on the inherent seakeeping advantage of SWATH ships, there should be a cleardemand for small SWATH boats, for which reduced motion underway, or at rest, in waves isessential.

5. Cargo Carriers

Considering the available SWATH deck area and the volume/weight requirements of certaintype of high value of goods (light containers, electronics, fish products, flowers, etc.),combined with a fast loading-unloading system (Lo-Lo or Ro-Ro concept), it seems that a fastSWATH container carrier of medium to large size should be a valuable alternative to existingconventional shortsea transportation systems (see, e.g., SMUCC concept, App. B). FurtherSWATH cargo carmer concepts, considered so far by European shipyards, include large LNGand H2 gas carriers for the transshipment of large amounts of natural gas and liquid hydrogen.

6. Research - Oceanographic - Diving Support Ships

The inherent excellent seakeeping behavior of SWATH ships at low or zero speed, theirmaneuvering and station-keeping ability and the easy handling of oceanographic devices,submersibles etc., combined with the large available working area on deck and the spaciousliving quarters for scientists and crew, makes the SWATH concept ideally suited for operationsas multipurpose research or undersea support vessel. Various applications have been alreadyimplemented in several countries around the world and this trend will possibly increase in thefuture, as traditional research/oceanographic vessels will be replaced by modem newbuildings.

A. D. Papanikolaou. "Developments and Potential in Open Sda SWATH Concepts",WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow. September 1996.

15 08/09/96

7. Small Navy Ships, Offshore Patrol Vessels

The ability of a SWATH vessel of relatively small size (light 'corvette" class) to support a lighthelicopter, together with its excellent seakeeping performance in high seaways (especially incoastal waters) at an appreciable speed, enables the operator to efficiently supervise a far largerarea than any of the alternatives of comparable size can offer. This increases eventually theoverall efficiency of the available naval or patrol forces, since larger ships will be relieved fromsmall patrol duties.

8. Large Navy Ships

Many promising SWATH warship applications have been outlined in a series of studies,especially of the U.S. Navy, since the early seventies. The combination of the excellentSWATH seakeeping qualities with the inherently large and high deck makes the SWATH anatural concept for the support of naval aircraft forces. Besides current known applications aslarge open sea surveillance vessel (T-AGOS 19 class, US Navy and 1-lIfIlBA, Japan DefenceForces) it appears that the light aircraft (V-STOL) and helicopter carrier (displacement abt.10.000 tons, carries, e.g., 16 Helos plus additional military payload) and the medium sizecombatant ASW concept (displacement abt. 6.000 tons, carries, e.g., 5 Helos plus additionalmilitary payload) are the most promising concepts, to be implemented in the years to come.

CONCLUDING REMARKS

With the SWATH concept in its original or hybrid form now fully proven by variousfull scale examples it seems that time has come to see in practice more and more SWATHapplications, despite obvious hesitations by operators and shipbuilders, who might look foralternatives that are not always justified by rational reasoning. A wealth of research andengineering developments in SWATH technology over the last three decades ties still waitingto be converted into practical applications. It seems, that as seakeeping, safety and high-speedare gaining on importance for various merchant and navy applications, SWATH will eventuallybe a very serious alternative to be followed in the future.

By its nature, the present paper, does not claim to deliver a complete "state of the art"on SWATH technology, because of the restricted availability, to the author, of non-publicdomain data. However, several trends and the potential of SWATH technology have beenoutlined. The following list of references is not exhaustive, but the work of many hereunnamed authors who contributed to the present state of the art is acknowledged. Finally, theauthor likes to thank all members of the SDL-NTUA research team, who contributed in thepast 10 years with great enthusiasm to the development of various design tools of the NTUA-SDL Laboratory, enabling the completion of a large variety of SWATH and SWATH Hybriddesigns, given the constraints of an academic environment.

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts'"WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow, September 1996.

16 08/09/96

REFERENCES

1. Akagi, S., 1991, "Engineering Design", Vol. 1, Coruna Publ. and "Synthetic Aspects ofTransport Economy and transport Vehicle Performance with Reference to High Speed MarineVehicles", Proc. FAST'91 Conference, Trondheim.

2. Allen, R. G., Holcomb, R. S., 1982, "The Application of Small SWATH Ships to Coastal andOffshore Patrol Missions", Proc. RINA Spring Meeting, Conf., London.

3. Betts, C. V., 1988, "A Review of Developments in SWATH Technology", Proc. Int. Cond. OnSWATH Ships and Advanced Multi-Hull Vessels II, RINA, London.

4. Eames, M. C., 1980, "Advances in Naval Architecture for Future Surface Warships", Proc.RINA Spring Meeting Conf., London.

5. Kennel, C. G., 1985, "SWATH Ship Design Trends", Paper in Proc. Int. Contt On SWATHShips and Advanced Multi-Hulled Vessels, RINA Publ., London.

6. Kennel, C. G., 1992, "SWATH Ships", Technical & Research Bulletin No. 7-5 prep. For SD-5Panel of the Ship Design Committee of SNAME, SNAME Publ., Jersey City..

7. Lang, T. G., Slogett, J. E., 1985, "SWATH Developments and Performance Comparisons withOther Craft", Paper in Proc. Int. Conf. On SWATH Ships and Advanced Multi-HulledVessels, RINA Publ., London.

8. Mac Gregor, J. R., 1987, "Historical Development of the SWATH Ship Concept", Univ. ofGlasgow Rep. NAOE-87-44, Glasgow.

9. Papanikolaou, A., Zaraphonitis, G., Androulakakis, M., 199 1, "Preliminary Design of a High-Speed Passenger/Car Ferry", Journal Marine Technology, Vol. 28, No. 3.

10. Papanikolaou, A., 1988-90, "Hydrodynamic Aspects and Conceptual Design of SWATHVessels", Progress and Final Report to the Greek Secretariat General for Research andTechnology.

11. Papanikolaou, A., 1990-94, "On the Stability of a SWATH Ferry in Calm Water and inWaves", Proc. STAB'90 Conf, Naples, "On the Dynamic Stability of a SWATH ResearchVessel in Following Seas", Proc. STAB'94 Conf., Florida.

12. Papanikolaou, A., Androulakakis, M., 1991, "Hydrodynamic Optimisation of High-SpeedSWATH', Proc. 1 st FAST Conference, Trondheim.

13. Papanikolaou, A., 1991, "Computer-Aided Preliminary Design of a High-Speed SWATHPassenger/Car Ferry", Proc. 4th IMSDC Conf, Kobe.

14. Papanikolaou, A., Bouliaris, N., Koskinas, C., and Pigounakis, K., 1995, "SMUCC - SWATHMultipurpose Container Carrier", Paper in Proc. FAST '95, Germany.

15. Papanikolaou, A., Kaklis, P. D., Koskinas, C., Spanos, D., 1996, "HydrodynamicOptimization of Fast Displacement Catamarans", Proc. 21st Symposium on NavalHydrodynamics, Trondheim.

16. Zachsial, M., 1994, "European Short Sea Shipping", Paper in Proc. of 2nd European ResearchRoundtable Conference on Short Sea Shipping - Athens, Delft Univ. Press Ltd, Delft.


17 08/09/96

LIST OF APPENDICES

APPENDIX A:

Tables of built SWATH ships and Characteristic Designs

APPENDIX B:

SMUCC - An innovative SWATH Multipurpose Container Carrier concept

for Shortsea Shipping

APPENDIX C:

Examples of validation of theoretical predictions of SWATH

calm water and seakeeping performance by model experiments

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts".WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow, September 1996.

18 08/09/96

APPENDIX A:

Tables of built SWATH ships and Characteristic Designs


19 08/09/96

TABLE 1.1 SWATH Demonstrators-Prototypes

SHIP NAME SSP KAIMALINO MARINE ACE ALlLENGTH, QA [ml 26.27 12.35 11.27LENGTH, BP [m] 22.23 11.00 9.14

BEAM, WL/OA (m] 13.41/14.32 5.80/6.50 4.60/4.90LOA/BOA 1.87 1.90 2.47

DEPTH [m] 8.84 2.70 3.05DRAFT [ml 4.66 1.55 1.58

STRUT TYPE TWIN TWIN/SINGLE SINGLELOWER HULL TYPE cylindrical cylindricalHULL MATERIAL STEEL/AL AL STEELDISPLACEMENT/ 190 - 217 (max.) / 18-22 21PAYLOAD [tons] 50 (inl. fuel)

POWER [SHPI 4.400 400 140PROPELLER TYPE CPP FPP FPP

SPEED [knots] 25 18 7.6FROUDE 0.86 0.89 0.41

COMPLETION 1973 1977 1990DATE

BUILDER CURTIS BAY MITSUI Shipb. Co. G. SMALL /US Coast Guard Yard JAPAN G. Mc GREGOR, UK

OWNERIOPERATOR NAVAL OCEAN MITSUI Shipb. Co. G. Mc GREGOR, UKSYSTEMS CENTER- JAPAN

NOSC, HAWAII, USA

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts",WIEGEMT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow, Sept. 1996

1 08/09/96

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SHIP NAME T-AGOS 19 HIBIKISHIP TYPE Surveillance Vessel Surveillance Vessel

LENGTH, OA fml 71.32 67.06LENGTH, BP (ml 57.91 61.87

BEAM, WLIOA [m] 24.38/28.65 24.69/29.87LOA/BOA 2.49 2.24

DEPTH [m] 15.24 15.24DRAFT [mI 7.56 7.62

STRUT TYPE SINGLE SINGLELOWER HULL TYPE CYLINDER/CONICAL CYLINDER/CONICAL

HULL MATERIAL STEEL STEELDISPLACEMENT [tons] 3.400

POWER ISHP] 1.600 3.000PROPELLER TYPE FPP

SPEED (knotsl 10.4 11FROUDE 0.23 0.23

COMPLETION DATE 1991 1991BUILDER Mc Dermott Shipv.. USA MITSUI Shipb. Co., JAPAN

OWNER/OPERATOR US Navy Japan Defence Forces

A. D. Papanikolaou. "Developments and Potential in Open Sea SWATH Concept".IVEGa•IT Workshop on Conceptual Designs offast Sea Transportarion. Glasgow, Sept. 1996

4 08/09/96

TABLE 1.4 SWATH Research Vessels

SHIP NAME KOTOZAKI OHTORI KAIYO FREDERIC G. CREEDLENGTH, OA [ml 27 27 60 20.4LENGTH, BP Iml 25 24.08 53 16.8BEAM, WL/OA 10.06/12.50 10.06/12.50 22.9/28 8.22/9.75[m]LOA/BOA 2.16 2.16 2.14 2.09DEPTH [m] 4.6 5.2 10.60 4.88DRAFT [m] 3.20 3.41 6.30 2.60STRUT TYPE SINGLE SINGLE SINGLE SINGLELOWER HULL CYLINDER CYLINDER CYLINDER BOTTLE likeTYPEHULL AL/STEEL STEEL STEEL ALMATERIALDISPL. [tonsl 236 240 3500 80POWER [SHPI 3.800 3.800 4.680 2.160PROPELLER CPP CPP CPP FPPTYPESPEED [knots] 20.5 20.6 14.1 24FROUDE 0.67 0.67 0.32 0.96COMPLETION 1980 1981 1984 1989DATEBUILDER MITSUI MITSHUBISHI MITSUI SWATH OCEANS, USAOWNER JAPANESE JAPANESE JAPANESE CANADIAN

/OPERATOR MINISTRY OF MINISTRY OF MINISTRY OF HYDROGRAPHICTRANSPORT TRANSPORT TRANSPORT SERVICE

A. D. Papanikolaou. "Developments and Potential in Open Sea SWATH Concepts".fVEGECdT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow, Sept. 1996

5 08/09096

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APPENDIX B:

SMUCC - An innovative SWATH Multipurpose Container Carrier concept

for Shortsea Shipping

A. D. Papanikolaou. "Developments and Potential in Open Sea SWATH Concepts".WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow. September 1996.

20 08/09/96

Summary ofpres. at the 3rd International Conference on Fast Sea Transportation, Travemande,

September 1995

SMUCC - SWATH MUltipurpose Container Carrier

ABSTRACT

The present concept concerns the development of a fast SWATH Multipurpose

Container Carrier (SMUCC) for Short Sea Shipping operations in Europe. It is based on

the concept of fast sea transportation and rapid cargo transfer from road and rail to ship

with minimisation of the interruption of cargo flow to the extent possible. The concept

addresses, besides the prototype container carrier, the development of an innovative port-

terminal facility, enabling the rapid transfer of incoming containers from road, rail and

other sea carriers to the proposed SWATH carrier. Based on the high through-put speed

of the defined cargo transportation-chain and the high service speed of the vessel of about

30 knots, the concept promises a high frequency of departures and arrivals for the

candidate vessel, or fleet of similar vessels, at the ports of call. The study addresses the

main aspects of the overall concept and is focusing on the design and the economic

viability of the suggested container carmer.

1. SMUCC Loading-Unloading Concept

Given the availability of a high-speed vessel, of whatever type, there is little benefit for the

overall concept of fast sea transportation if much time lost at the port due to the slow

manoeuvring, mooring and cargo handling. The selection of the proper port location, so

that a high service speed can be maintained for most part of the route, the avoidance of


21 08/09/96

1. SMUCC Loading-Unloading Concept

Given the availability of a high-speed vessel, of whatever type, there is little benefit for theoverall concept of fast sea transportation if much time lost at the port due to the slowmanoeuvring, mooring and cargo handling. The selection of the proper port location, sothat a high service speed can be maintained for most part of the route, the avoidance oflong entrance channels and locks and of shallow water routes, are other aspects of any fastmarine transportation concept that have to be considered too, but they are outside thescope of this paper. The present SWATH Multipurpose Container Carrier concept-proposal addresses the problem of minimisation of the port time as following :

1. The proposed SMUCC carrier has excellent manoeuvring capability through twin hull,twin propeller, twin rudders and possibly through twin bow thrusters arrangements, thusberthing at the port is greatly simplified2. Docking of the suggested SMUCC carrier is taking place at a customised dockingfacility, fitting crosswise to the dimensions of the proposed ship (abt. PAN-MAXdimensions). It is assisted by an automatic shore- or vessel-based mooring system. Theproposed specialised dockingplace is shown in Fig. 1.3. The inherent sensitivity of SWATH ships against weight changes duringloading/unloading is alleviated by considering a medium waterplane area, hull formdesign and the provision of an efficient ballasting system. The crucial keeping of constantdraft and trim of the suggested vessel is supported by the suggested shore or vessel-basedautomatic mooring system (see 2.), ensuring the preloading of the vessel to the designdraft. After the loading/unloading has been completed the vessel can be released to sailout.4. The terminal facility, serving SMUCC (see Fig. 1), might be considered as animproved, inter-modal container terminal facility. Cargo units (aSo or EURO containersor similar unitised cargo) are brought to the terminal by rail or road or otherconventional ships or even other SMUCC ships. The units can be prestacked or directlyplaced on a remotely controlled , "double lane", rolling conveyor or rail, containerdistribution system. The concept considers sub-terminals, local control stations andlocal networks. The control of the movements of the cargo units is achieved through theapplication of modern data transmission systems (Electronic Data Interchange - EDI),considering also all the necessary paperwork, so that the cargo unit might be loadedwithout delays.5. The container transfer from the rolling conveyor to the ship is enabled by a shore-based gantry crane, overlooking the whole SMUCC docking place and the feeding of theland-based distribution network. The gantry crane might load the suggested SMUCCcarrier rowwise, in stacks of up to ten containers per movement. For it, the containersmight be necessary to the placed on pallets or cassettes, depending on the gantry cranehandling design.6 In case of partial loading/unloading of containers, according to the cargo destination,only specific containers will be touched, easily accessible from the top of the ship (no"overstowage" due to spread of containers over large deck area).


22 08/09/96

7 In case of berthing of the proposed SMUCC carrier at a non-specialised terminal, asdescribed above, the ship might be served as a conventional container ship,loading/unloading deck-containers. Berthing and mooring is simplified, trimming anddraft-keeping is provided by own ballast system.8. In an extension of the proposed SMUCC concept, considering a vessel of larger sizewith higher payload capacity, SMUCC might be operated within the so-called Bacat

(Barge Aboard CATamaran System of the Danish shipping company of G. Drohse in

1974, shipbuilder Frederikshavn Vaerft & Tordok A/S, see Witth4ff, 1982).

Fig I Sketch of SMUCC Inter-Modal Container Terminal

2. CONCEPTUAL SMUCC VESSEL DESIGN

2.1 Design Concept

The herein proposed concept of a SWATH Multipurpose Container Carrier (SMUCC) is

following the strategic principle of "function-separation", introduced by S. Akagi, 1991,

for the development of high speed marine vehicles, whereas the hull form of a

conventional ship retains a dual function, namely to accommodate the cargo in the holds of

the hull and at the same time to support the ship by its buoyancy. In developing container

transport vehicles for high value of cargo, requiring high transportation speed, the

resulting hull form for the containerships is consequently slender, with very limited space

in the holds. This fact led the designers "naturally" to the introduction of an increased

number of "deck" containers, thus splitting the dual function of the vessel's hull form and

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts".WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation. Glasgow. September 1996.

23 08/09/96

also enabling easy loading and unloading of the deck containers. However, this split offunctions was partially paid for by the carriage of "non-paying load" (permanent and/orwater ballast), due to insufficient stability reasons.

The proposed cargo SWATH (or in general the cargo catamaran, see Fig. 2) might beconsidered as a further development of the above concept towards a complete split ofarrangements and functions, with the deck (and the superstructure in general for other shiptypes) carrying the complete payload, easily accessible from the top or the side, and thetwin lower hull arrangement providing the buoyancy and accommodating the machineryand propulsion units, as well as all the outfitting to the extent possible. Despite theincreased frictional resistance of the twin hull configuration, compared to a monohull ofequal displacement (due to the increased wetted surface of a twin hull vessel, as comparedto a monohull of equal displacement), the hulls of a SWATH ship can be formed veryslender to experience low wave making and low pressure-viscous resistance, besides theincreased propulsive efficiency due to the slenderness and axisymmetric form of the lowerhulls. Thus at least some of the above drawbacks of the twin hull vessel concept arealleviated and therefore efficient and competitive SWATH hull forms can be developed formanifold operational profiles.

Fig. 2 Geometrical Modelling of SMUCC carrierTurning to the safety of the proposed carrier against capsizing, namely the transversestability problem affecting seriously the design of alternative high-speed monohull vessels,disappears herein trivially, due to the inherent transverse stability of twin hullconfigurations. On the other side, some typical deficiencies of the original SWATHconcept, namely the appearance of the vertical plane instabilities due to the action of theso-called MUNK moments, is addressed by the provision of "medium" sized waterplaneareas for the struts and the employment of two sets of not necessarily movable orautomatically controlled fins (see, Papanikolaou, A., 1990). Through the medium


24 08/09/96

waterplane area of the struts and the placement of the machinery and other outfitting in thelower hulls, the inherent trim, heel and draft sensitivity is counteracted by geometric anddesign (weight controlled) means to the extent possible. Finally, the drawback ofconsiderable draft of an original SWATH hull form, compared to alternative mono- ortwin-hull concepts, that might be of importance for certain Shortsea Shipping routes, canbe addressed by increased displacement volume in the waterplane area region or ellipsoidalcross sections, leading to SWATH-CAT hybrids.

Two important further characteristic of the proposed design are the used construction.material, namely steel, except for the aluminum superstructure, and the global structuraldesign of the vessel. Unlike current developments in the construction of much larger, thanthe suggested, aluminum SWATH like vessels (see, e.g., Finnyards-STENA's HSSproject), the present concept considers the use of a conventional shipbuilding material,namely steel, including higher tensile steel, where locally necessary for the loads carryingship structure. The concept relies on the simplicity of the design and the optimization ofthe structural design of the vessel to counterbalance the weaknesses of steel againstalternative construction materials in terms of the increased structural weight and thereduced payload capacity. Only the superstructure is considered to be built from aluminumalloy, but it is not considered essential for the present design, due to the limited extent ofthe ship's superstructure (bridge). The simplicity of the present SMUCC design allows thesplit of the main deck area into two main structural zones, namely the first one supportingthe deck superstructure at the forward one third of the ship's length and the second one isthe container-load carrying zone extending backwards over the remaining two thirds of theship's length. From the structural design point of view the forward part of the ship isrelatively stiff through the closed character of the corresponding frames extending from

the circular lower hull cross section to the vertical struts, the wedge type sponsons at thehighly loaded haunch area and to the connecting boxlike main-deck double bottom. Forthe container carrying deck area the present concept considers an open bedsteadconfiguration, consisting of a properly strengthened mainframe starting at the aft end of

the main deck and ending at the aft end of the forward superstructure and several equallyspaced boxlike transverse beams between the sponsons of the relevant frames, giving theopen deck-bedstead additional stiffness against transverse bending and torsional loads in aseaway. A similar concept, without the additional transverse stiffeners, was applied to theconstruction of the 43m LOA, steel SWATH "Navatek V" of Navatek Ships Ltd (seeTrillo R., 1991). It should be noted, that due to the proven excellent seakeeping of thesuggested SWATH vessel, the wave induced loads, including underdeck pounding, can beexpected to be lower than for comparable other designs for the same environmental

conditions.

A. D. Papanikolaou, "Developments and Potential in Open Sea SWATH Concepts".WEGEMT Workshop on Conceptual Designs of Fast Sea Transportation, Glasgow. September 1996.

25 08/09/96

2.2 Technical Approach

A common ship design procedure considers, in the first step, the specification of theowner's requirements in terms of the payload capacity and speed for the ship, as well asoperational and environmental conditions in the framework of a transportation scenario. Inthe present case the requirements for the design are of qualitative nature, namely thehypothetical shipowner is assumed to

... a ship design that allows the quickest possible cargo transfer from road and rail toship and vice versa including proposals how to minimise the interruption of cargo flow.The design has furthermore to be based on the necessary collection of small lots of cargoand not of bulk with high frequency of departures and arrivals...

The above requirements are herein interpreted as following:

1. The vessel should, for the sake of innovation, be unconventional or fiituristic, thus itshould deviate substantially from existing other designs.2. The vessel should be suitable for Short Sea Shipping, thus, it will be, at first, of limitedsize and general dimensions.3. The design, including the overall transportation concept, should allow quickest cargotransfer from road and rail to ship and vice versa, thus the incoming cargo must bepreloaded in standard transportation units, like ISO or EURO containers, allowing thequick transfer within a transportation network, consisting of land, sea and even airtransport vehicles. Also the requirement for quick transfer suggests that the transportedgoods are of high value. They must be secured against damage and loss, thus placed incontainers, and transported fast over the sea. Insofar, it is expected that the proposeddesign concerns a high-speed container carrier for Short Sea Shipping operations.4. The proposed concept should include proposals how the minimise the interruption ofcargo flow, thus it should consider a proper container terminal installation, allowing theprestacking of incoming containers by land transport and the quick transfer onboard,whereas the sea transporter itself must be operative year-round and independent ofenvironmental conditions.5. Finally, the concept should consider the collection of small lots of cargo with a highfrequency of departures and arrivals of the vessel at the ports of call, thus besides theeasy loading and unloading of specific containers, the ship must be fast both over the seaand during landing to the port (high manoeuvrability and berthing ability).

Based on the above requirements the conceptual design of a high-speed, feeder containercarrier of SWATH type, so-called SMUCC, with the main characteristics given in Table Ihas been developed at SDL-NTUA. The suggested SWATH container carrier has twoalternative options for the machinery installation, namely an option for the arrangement oftwo (2) MTU 20 V 1163 TB 73 giving the vessel a service speed of abt 26 knots (topspeed 28 knots) and a second version with four (4) MTU 20 V 1163 TB 73 diesel enginesgiving the vessel a service speed of abt 36 knots (top speed 38 knots). The payload


26 08/09/96

capacities varyaccordingly between 430 tons for the first option and 360 tons for the

second, assuming a range of abt. 400 sm. The deck arrangements of the vessel allow thetransport of up to 60 TEU containers in six rows of ten units each crosswise or of other

box units of non-standard size, justifying the Multipurpose character of the proposed

design.

Table 1 SMUCC - Main Dimensions and Technical Characteristics

Length O.A. 51.50 m Deck Length OverallBeam O.A. 31.70 m Deck Beam OverallLength of Hulls 50.00 m Length of Lower HullsMax. Beam of Hulls 3.80 mn Diameter of Lower Hulls - locallyLength of Struts 37.60 m Length of Strut at WaterlineMax. Beam of Struts 2.60 m Beam of Struts - locallyDraft 5.00 mn Fully loadedDisplacement 1060 tonsLight Ship 563 (633) tons Dep. on mach. installation 2(4) enginesDeadweight 497 (427) tons ( ) values for 4 engines versionPayload 430 (360) tons 6 x 10 TEU containers,

( ) values for 4 engines version

Service Speed 26 (36) knots ( ) values for 4 engines versionHorsepower (MCR) 14800 (29600) HP 2 (4) x MTU 20 V 1163 TB 73

2.3 Preliminary Economic Analysis

It is clear that a fast ship will have, in general, increased operational cost, due to

higher initial investment cost and increased fuel cost. Thus it will require higher freight

rates, as compared to a traditional low-speed vessel. However, in evaluating the

economics of such vessels the "total economy" of the transportation scenario must beconsidered (e.g., "value of time" of cargo, savings in storage, "just in time" demands - JITproducts, etc., see, e.g., Levander, K., 1992, Proc. 1" Shortsea Shipping Roundtable

Conference, Delft, and commentary by Wergeland, T, 1992). We address in the following

some basic data for the economic evaluation of SMUCC, considering a hypothetical

transportation scenario. This scenario considers a transportation work of 48 TEU x

132.000 miles/year, or 6.336.000 TEU miles/year. The latter is estimated on the basis of atraveling distance of moderate 400 miles/day (service speed abt 28 knots) and abt 330

operating days/year, and an annual average 80% capacity utilization (80% of the available

60 TEU). On the basis of the above data the following preliminary economic results have

been obtained for SMUCC.


27 08/09/96

Table 2 Main techno-economic characteristics of high-speed SMUCC

Displacement 1060 tonsPayload 430 tons (V.2) to V.2 2 engines version, 26 knots

360 tons (V.4) or V.4 : 4 engines version, 36 knots60 TEU containers 7.2 to 6 tonslTEUPayload used 48 TEU containers 80% utilisationHorsepower 10800 kW V.2 : 2 engines version, 26 knots(service) 21600 kW V.4 :4 engines version, 36 knotsInvestment cost 14 Mio $ US to V.2 : 2 engines version, 26 knots16 Mio S US V.4: 4 engines version, 36 knotsFuel Cost (incl. 10% 2.7 Mo $ US to V.2 :2 engines version, 26 knotsmargin) 3.8 Mio S USV.4 : 4 engines version, 36 knotsOperating Cost 3.6 Mn $ US to V.2 : 2 engines version, 26 knots

5.1 Mio S US V.4 : 4 engines version, 36 knotsRFR per 0.9 $ US /(TEU x sin) V.2 : 2 engines version, 26 knotsTEU and sm 1.2 S US/(TEU x sin) V.4 :4 engines version, 36 knotsRFR per 0.125 $ US /(ton x sin) V.2 :2 engines version, 26 knotston and sm 0.200 S US/(TEU x sin) V.4 : 4 engines version, 36 knotsRFR per 180 $ US /TEU V.2 :2 engines version, 26 knotsTEU for 200 sm 240 $ US/TEU V.4 : 4 engines version, 36 knotsRFR per 25.0 $ US /ton V.2 : 2 engines version, 26 knotston for 200 sm 40.0 S US/ton V.4 : 4 engines version, 36 knots

Although the above data can be considered only preliminary, it seems that theproposed high speed SMUCC container carrier can be very competitive against alternativefast cargo ships of comparable size or even traditional ships, when the value of time of thetransported goods or even storage and additional costs demand a higher turnaround speed,both over the sea as well as at the ports of call. It should be noted that the above numbersfor the RFRs of abt. 0.125 to 0.200 $ US/ton mile for abt 26 to 36 knots of speed ( 48.2to 66.7 km/h) compare fairly well and are even lower than the comparable numbers givenby K Levander, 1992 for the much larger EuroExpress design. Note that according to K.Levander traditional shipping might charge 0.08 $ US/ton mile for 17.5 knots of speed,however with additional storage and handling cost of abt. 40 $ US/ton and at least doublehandling and storage time. Also note, that the operation of the present ship at 17 knotsrequires only 5500 BHP and the resulting RFR might be even below 0.08 US/ton mile.Thus, reducing or even eliminating the storage and handling time with the proposedSMUCC concept, the "total economy" might be very competitive, even against traditionalslow shipping systems. Finally the achieved transport speeds of between 50 to 70 km/hseem very competitive to land transport speeds by road. However, the validation of theabove data remains to be done in the framework of a more complete and detailed techno-economic analysis.


28 08/09/96

APPENDIX C:

Examples of validation of theoretical predictions of SWATH

calm water and seakeeping performance by model experiments

Ref. : Proc. 21st ONR Symposium on Naval Hydrodynamics, Trondheim, 1996Proc. li FAST '91 Conference, Trondheim, 1991


29 08/09/96

A. Papanikolaou et a], Proc. 2 1" ONR Symposium on Naval Hydrodynamics, Trondheim, 1996

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FIg . 3 H e av e a n d • i l c f F AO s 0 1 m o o l i . i 'e 3 3 w a v e s F - = .53 5 o 0 0 n o o ro r 5 1 1 1 0 w a[ o i n s ( -i i S i f l Z Ih o o r w 1 1h o u- - - ),

moasuremnerns wI~oir•f;s La). moasurcinen:s w•fhoul fins (A). J, 3D heor" Wi::h is ( * L. and JO Iheo~y W';tout fins C • *

A. D. Papanikolaou. "Dcveloprncos and Polential in O`en Sea SWATH Concepts".

WVEGEAIT W•orks~hop on Conceptuol Desig ns v/Fast Sea TransportatiOn. Glasgo w. Sep,. /996

08,'09/96

A. Papanikolaou et al, Proc. 2 1' ONR Symposium on Naval Hydrodynamics. Trondheim. 1996

FROUDE NUMBER FRCUOE NUMB.ER0. 0. , n i A Os 07.5 0.22 0.7 0.30 0.34 0.38 0'2 0,6

-7 0 0 0 6 0 0 0 '- - " 2:-,' Z4.C. '-.flQO"

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Zi=M0 4000 ... (20) CMA445e-6000 : -£tPERm.. (NMA)

5000 (s/L-0.42) O . = : I4PO . C=Ms - -eM)0 .. - -J~ o _ _ : @t.5••,,• . v,-e.,w,)

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0 - I - 0 1 2 1 4 1 6 i 2 0 2 2 2 4 ,2 2 I 1 1 1 4 1 I- 1 1 198 - -2 0 1 2 2 2 ,3SPEED (kn) SPEED (kn)

Fig. 12 Comparison between theoretical Fig. 13 Comparison between theoreticalpredictions and model experiments for the predictions and model experiments for theEffective Horse Power of SIMICAT Effective Horse Power of GOUTCA T

Fig. 14 View ofCGOUTCAT model tested at VWS Berlinupper pan: model in scale 1: 16 (LOA = 4 ,928m)

lower part: propulsion test at design speed (v = 21 knots)

1A*

wegemt workshop...incat 74 metre wave piercing catamarans from tasmania in 1990. the industry then...

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