SPECIAL SEMINAR

SHIP LIFT SYSTEM

1. DEFINATION2. DIFFERENCE WITH DRYDOCK3. SETUP AND WORKING4. WORKING PROCEDURE5. DESIGN LOADS ACTING6. DESIGN PRINCIPLES7. CLASS DESIGNATION8. SYNCHROLIFT SHIPLIFT AND TRANSFER SYSTEM9. SHIPLIFT SYSTEM IN INDIA10. PARTS OF SHIPLIFT SYSTEM11. ADVANTAGES 12. DISADVANTAGES

TABLE OF CONTENTS

DEFINATION OF SHIPLIFT A shiplift is a large elevator platform, which can be lowered into

water, have a ship hauled-in and positioned over the cradle/blocks present on the platform and then lifted vertically to the yard level, so that the ship can be moved from the platform on to a dry repair berth on land.

Alternative way to dock a ship without a dry dock , floating dock or pontoon docks

Electrically controlled lift platform that lifts ship from water with help of a number of lift winches.

Also occupied with transfer system to transfer ship from platform to workup area through railings.

Electronic sensors keeping track loads on each winch and load distribution and alignments.

DIFFERENCE WITH DRYDOCKDRYDOCKING - the traditional method

1.) Ship is guided to a docking berth2.) The berth is sealed from the sea water by the walls3.) The water is drained out during which the ship is made to rest on the block

SETUP AND WORKING

STEP 1 HERE THE SHIP IS GUIDED INTO THE LIFT

AREA BY THE HELP OF TUGS

Once the ship has properly entered the area the ship is secured along the berthing area by means of lines

STEP 2 THE SUBMERGED PLATFORM IS SLOWLY LIFTED UP BY

MEANS OF HOISTS WHEN THE PLATFORM IS LIFTED THE CRADLES WHICH

ARE SECURED TO THE PLATFORM RISES UP THE FIRST CONTACT IS NOTED CAREFULLY BY

ANALYSING THE LOAD ON EACH HOIST THE WOODEN BLOCKS -ALREADY SECURED ON THE

CRADLE ON THE BASIS OF HULL GEOMETRY- CONTACTS THE SHIPS HULL AND THE SHIP STARTS ITS VERTICAL ASCENT

STEP 3 When the platform has fully risen to the

ground level the trolleys are moved in The trolleys then lift the cradles on the

hydraulic lifts on its surface. these trolleys operate in a synchro and carry the ship to its repair area

EXPLANATION

A shiplift consists of a steel lifting, platform, suspended by wire ropes attached to hoist drums, raised and lowered vertically by a series of hoists.

The hoists are distributed in equal numbers on either side of the platform and are located on piers or foundations.

The hoists are driven in a synchronised mode. By synchronising all the hoists, the platform with or without a ship is raised or lowered vertically, uniformly and in a horizontal plane. Finer levelling adjustment is built into the system.

The shiplift is controlled and operated from a control system and operator console. The control system has a number of in-built safety mechanisms in order to prevent incidents that may arise due to overloading or underloading conditions or severe imbalance of the platform due to shipload and a variety of other causes.

The Ship Transfer System is of modular design and

construction so that it can be reconfigured to suit varying lengths and beam of Indian Navy ships. The modular system greatly enhances the flexibility and versatility.

In the current program, two sets of these modular cradles are included for dry docking 2 ships; additional sets can be added for each new berth, as and when constructed.

The ships and cradles are transported by a self-driven hydraulic bogy system, both longitudinally and transversely. Only one set of hydraulic bogies is required for the ship movement and transfer operations in the yard. The bogies need not be immersed in seawater.

By interconnecting and grouping the hydraulic bogies, the heavier sections of keel loads can be redistributed more evenly and thus heavier ships lifted

DESIGN LOADS ACTING ON SHIPLIFT SYSTEMS 

1. Nominal lifting capacity (NLC)The nominal lifting capacity NLC is the sum of all loads (weight of ship and weight of the variable parts of the equipment, like carriages, ship bearing blocks,etc.). Usually it is defined in metric tons [t]. 2. Lifting load for design (MDL)The lifting load for dimensioning MDL is created from the nominal lifting capacity (NLC) by increasing it with a certain factor and will be distributed equally as a line load along the centre line of the platform. MDL = 10 NLC * ϕ /Leff [kN/m] NLC = nominal lifting capacity [t] Leff = effective length of the lifting platform in [m], which serves to carry the loads of the nominal lifting capacity NLC.

 Φ = load distribution factor  The load distribution factor takes into consideration the unequal

distribution of the ship’s weight at the platform axis as well as dynamic effects during docking and can be defined with ϕ= 1,33 for regular cases. The actual size of this factor has to be agreed with GL,taking into account the actual operating conditions.

 3. Live loadApproachable platform areas not foreseen to be used by live loads have to be calculated using at least the following loads:  An uniformly distributed load of 5 kN/m2, (simultaneous action

of this traffic load and the lifting load for design MDL must not be assumed for regular cases)

A singular point load of 10 kNFor designing, the locally more disadvantageous load has to be chosen.Platform areas foreseen to be used for working and transport have to be measured according to the expected maximum live load.

DESIGN PRINCIPLES  Under loaded condition the speed of lifting and

lowering is restricted to a maximum of 0,5 m per minute. For operations without load, higher speed is permissible.

 For the transfer of the ship to the shore the platform has to be locked at the actual transfer side. Ship lifts, which are also used as a working platform (e.g. for ship repairs), have to be mechanically locked on both longitudinal sides for this working condition.

It is assumed, that wind and waves do not create vibrations of the ship lift loaded with a ship, which are not acceptable from safety point of view. Undue movement has to be prevented by guiding devices.

 

A horizontal alignment of the lifting platform has to be aspired. Inclinations and height differences between adjacent lifting equipment, which are not avoidable during operation have to be limited, that no exceeding of local stress, inadmissible load cycles and disturbances of functions appears. 

The deflection of the girders for the travelling rails should not exceed 1/800 of the distance between two supports.

For bolted connections of platform girders preloaded high-tension bolt connections should be chosen

Class designation In proof of classification ship lifts obtain

the class designation 100 A5 appended the notation "SHIP LIFT" and the nominal lifting capacity NLC in [tons].

Synchrolift shiplifts & transfer system

SYNCHROLIFT SYSTEMSA Syncrolift system is simply a large elevator which raises and lowers vessels in and out of the water for dry-docking ashore.WORKING OF SYNCHROLIFT SYSTEMS To dock a vessel, the platform and cradle are lowered into

the water, and the vessel moved into place over the platform. 

When in position, the Syncrolift Dockmaster raises the platform, removing the vessel from the water. 

Work on the vessel can then be done in situ, or the vessel transferred ashore, leaving the Syncrolift available to dock other vessels. 

On completion, the process is reversed. 

. FEATURES OF SYNCHROLIFT SYSTEMS Speed of operation - more ships docked per year. For example - one of our

larger customers performs over 500 drydocking contracts each year using its single shiplift. Typically some of our units are operated 6 - 10 times daily. A Syncrolift minimises the space required for launching ships at the waterside and the transfer system ensures maximum use of the shore work area. 

Patented ATLAS Dockmaster® control system - provides the operator with information about the ship that is being lifted. This information enables the operator to analyse the distribution of the load being lifted, and hence to protect the vessel during the docking operation. No other drydocking system does this. It also provides condition monitoring data on the shiplift, which reduces the requirement for routine maintenance and extends component life. 

Simpler and faster drydocking procedures - requiring fewer personnel and less man hours to successfully drydock vessels. Typically, drydockings take 25 - 50% less time because of the improved access provided for both labour and materials. A Syncrolift requires no prolonged shutdown period for maintenance. 

Long service life -  The Syncrolift shiplift system will not lose capacity in future years due to deterioration of inaccessible underwater parts.

 

  Syncrolift® shiplifts - self-protecting against electrical and

structural overloads and self-protecting against operation beyond permissible up and down limits.

The shiplifts modular design - permits future expansion of the original installation to obtain increased lifting capacity, to provide a dual lifting capacity, to increase platform length or to generally increase the system capabilities.

Drydock alternative - One Syncrolift shiplift with a transfer system can replace several floating dock or drydock facilities and facilitates the use of modern shipbuilding and/or ship repair techniques, such as modular construction. 

Minimise space - The Syncrolift design minimises space requirements at the waterfront. When combined with our transfer system, multiple work berths can be created to provide efficient and environmentally safe work areas well away from the water. All work can be safely contained without polluting the waterway.

Shiplift system in india1. GOA SHIPYARD LIMITED Features of the ship lifting yard Docking plan is made for the ship to be lifted by the design section

using CAD/CAM . Chokes are placed over trestles. Trestles are placed over the lifting

platform using boogies Ship is placed over the platform which is submerged in water Control room has sensors to checks to see whether the ship is placed

over the chokes, if required divers are sent . A set of 28 winches are used to lift the ship slowly . Trestles take the load from the chokes . Trestles have SWL of 336tons,boogies have SWL of 200tons, the

boogies have a bottom jack to rotate the boogies in required direction for shifting of the ship to required bay .

SPPS (self propelled power station) provides the hydraulic pressure (for the movement) & lift pressure(for lifting), oil suction and ejection provides the hydraulic mechanism involved

Each winch has a SWL of 375tons . 3 steel wires in combination of three are used for better

support The lifting speed is 5mins/m, and it can go down till a depth

of 10.7m . Testing of the shiplift system is done with barges of suitable

weight usually 1.5 times the swl . The chokes are 300mmx1200mm, the chokes are made of

top layer of soft wood and bottom layer of hard wood,they are connected by staplers and surrounded by a layer of mild steel, which in turn is welded to the trestle by a flat bar.

There is a deadman’s switch which switches off the heaving system every 150 secs to prevent any damage to the shiplift system.

The trestles are placed every 4.8m apart ,they are usually made to coincide with bulkheads or web frames .

Spring lines are used to align the ship inside the lift bay.

 100 Tons Capacity Shipyard Unit Transporters (Two Numbers)

 Two Land Berths For Dry Berthing

250 Mtrs Long Jetty

Shiplift & Transfer System The shiplift system is capable of docking the vessels up to

6000T and 120 mts Long X 20 mts WideLength Overall : 120 mtsBreadth : 25 mtsLifting Capacity : 6000 Tons

2. INS KADAMBA

DIMENSION : 178m x 28m CAPACITY : 10000 tons

PARTS OF A SHIPLIFT SYSTEM

1.) PLATFORM IT CONSISTS OF BEAMS SUPPORTED AT EACH END BY

THE HOISTS. THE BEAMS MAY BE CLASSIFIED AS –

1.MAIN TRANSVERSE BEAMS2.LONGITUDINAL BEAMS3.INTERMEDIATE TRANSVERSE BEAMS

THE MAIN CHARECTERISTIC IS THAT THE PLATFORM IS ARTICULATED..

IT MEANS THAT THE PLATFORM IS NOT RIGID BUT ADJUSTS ITSELF IN THE VERTICAL DIRECTION.

EACH MTB HAS ITS OWN SET OF HOISTS SO THE LOAD IS EQUALISED ON EACH OF THE HOISTS DURING THE LIFT OPERATION

2.)HOISTS/WINCHES Electrically operated , to lift the platform along with ship at a

uniform rate of load Each hoist is specially designed 3-φ ac synchronous induction

motor The motors operate at fixed speed and the control system

software protect against high loads.

3.)TROLLEYS/BOOGIES/CARRIAGE They are the part of transfer system which use hydraulic system

to lift the trestle and transfer ship along the railings The trolleys lift the cradles from the platform Then the trolley moves on the rails and takes the ships to its

respective repair area

4.)BLOCKS/TRESTLES These are the steel blocks on which ship rests. Blocks are the wooden planks shaped and arranged in

a optimum way as to reduce damage to the ships hull

DEPENDING ON THE LOCATION OF PLACEMENT THEY ARE CLASSIFIED AS

BILGE BLOCKS KEEL BLOCKS

5.)CONTROL SYSTEM Located in contol tower of the ship lift system has sensors to

sense load on each winch, control lift operations ,check alignment etc. startup

automatic on upon software startup

"power' panel main power switch

"alarms"panel accept button

"winches "panel activate button

platform control panel(up & down or lock & unlock buttons)

platform control panel stop button or auto stop

winches panel deactivate button

shut down software

shutdown

6.) SPPS(SELF PROPELLED POWER STATION)

Provides the hydraulic pressure (for the movement) & lift pressure (for lifting),oil suction and ejection provides the hydraulic mechanism involved .

ADVANTAGES OF SHIPLIFT SYSTEM

Much faster than other docking methods. Provide easier ways of launching avoiding

slipways and calculations. Avoids problems related to unavailability of dry

docks or limited dry dock through ship transfer system.

Avoids risk of dock gate and provides and open and easier accessible work areas

One platform can lift several ships without any space restrictions

Free space available for the convenient repair work

DISADVANTAGES OF SHIPLIFT SYSTEM

Restriction on dimension and displacement. High cost of installation Requires frequent maintenance and safety checks. Operation to be done very carefully and there can be

chances of ship to roll aside if seating is incorrect before lift on the blocks.

Not suited for ships whose under water area is damaged, hull is cut, very old hulls

Experiences full wind forces as there is no shelter Precision and accuracy are required for the smooth

functioning Lot of machinery involved which makes it vulnerable for

damage