eu project floodstandfloodstand.aalto.fi/info/examples/workshop_presentations_0702201… ·...

EU project FLOODSTAND –Designer’s viewpoint and comments

INTEGRATED FLOODING CONTROL AND STANDARD FOR STABILITY AND CRISES MANAGEMENT

Partner(s): Henning Luhmann, MEYER WERFTAnna-Lea Routi, STX Europe

“FLOODSTAND (218532) Final Workshop/Seminar”Aalto University DIPOLI Congress CentreFinland, Espoo, Otakaari 24February 7th 2012

7 February 2012 Final Public Workshop Helsinki 2

Contents

• Sample Ships• Simulations vs statutory rules• Results of WP 1,2+3• Results of WP 4,5+6• Effect on designs

– Crossflooding through ducts– Flooding through firedoors– Fire doors on bulkhead deck– Cold rooms– Watertight doors– Comparison cruise vessels / ropax

• Outlook and conclusions

7 February 2012 Public Workshop Helsinki 3

Sample ships

• Two sample ships provided by the shipyards• Ship #1

– Large cruise vessel 130000 GT, 5600 persons onboard

• Ship #2– Medium size cruise vessel, 60000 GT, 2400 persons on board


Sample ships

• Both ships represent actual cruise ship designs

• Comply with SOLAS2009 and SRTP

• Cover the majority of ship sizes– No ultra large ships like Oasis of the Seas– No small cruise ships

• Ropax vessels are not included– Special requirements and design features need to be addressed separately

• Cruise vessel have different flooding behaviour and design contraints than ropax vessels


Simulations versus static calculations

• Statutory rules require static damage calculations• Sequence of flooding considered only by stages and phases

• Two kind of simulations are used– Time domain flooding of single damage cases

• Better understanding of flooding inside the vessel– MC simulation to assess the overall level of safety

• Usually including influence of waves

• Results of simulation sometime significantly deviate from each other and from static calculations– What is right, what is wrong?– How can the static calculations be improved to be as close as reasonable to

reality


Simulations versus static calculations

• Static calculations easy to control by designers• Simulations may be used for special cases

– E.g. to determine accurate crossflooding time with restrictive effect of air pressure• MC simulations usually a “black box”• Assumptions for static calculations need to be commonly agreed by IMO• Attained index according SOLAS 2009 may differ from real survivability

– It is an agreed standard to compare the survivability of ships,it is a subdivision index rather than a survival index

• During development of SOLAS2009 simplifications are agreed:– B-walls are not to be considered– A-class boundaries and refrigerator spaces will delay flooding intermediate stages to be

calculated– Cross flooding through ducts based on one CFD analysis only– Effect of air pressure extremely simplified (10% rule)– Time domain calculations, CFD analysis or model tests may be used as an alternative to

MSC 283(85)

Are these simplifications correct?


Result of WP1, 2 and 3

• Assumptions as for SOLAS2009 have been partly confirmed by full scale tests– B-walls and doors collapse very fast– Cabins in wt-compartments are assumed to flood simultaneously– Fire doors may sustain a water level of 2.5m– Cold rooms may sustain a water level of 3.5m– light watertight doors may sustain a water level of 5.2 m– windows located on 2nd tier may sustain water level >18 m

• Crossflooding through ducts to be adapted– Original method too optimistic– Effect of air pressure over estimated

• Flooding simulations very robust and provide accurate results even with a reasonable coarse data model


Result of WP4,5 and 6

• Findings are difficult to transfer in daily ship design– SOLAS74 ships used for analysis

• ESTONIA and MONARCH of the SEAS– LSA arrangement totally different today

• E.g. location of life boats at lower decks


Result of WP4,5 and 6

• Vulnerability calculation lead in the right direction– Calculation of vulnerability to be improved and confirmed with new ships– Showing the effect of various factors in one value easy to understand for the Master– Opening of water tight doors is the most serious factor

• This was known to every stability expert• Now it can be made visible and quantified

– The designers need to consider better the operational needs• WTD must only be used as secondary means of escape• All WTD must be kept closed at sea• The design must allow to keep the doors closed


Crossflooding through ducts

• Cross flooding through ducts proven design• Size of duct to be otimized between space for tanks and time to flood• Effect of air pipes over estimated

– 10% of crossflooding area• Better knowledge to predict time to flood


Flooding through fire doors

• Fire doors collapse at 2.5m water levelfire doors at tank top do not delay floodinginstantaneous flooding to be assumed

• The effect on A index is small, but spaces with higher fire risk can be easier arranged.


Flooding through fire doors

• Fire doors are the weak point in a A-class wall• Flooding sequence to follow the fire doors• Not any combination of adjacent A-class spaces to be investigated• Simplified and clearer calculation procedure

1

4

32

123

4

333 33 2

232

3

131

331

33

4 43

Damage Extent


Fire doors on bulkhead deck

• Fire doors sustain 2.5m water level with only small leakage• May be used to restrict progressive flooding on bulkhead deck• Improves subdivision without the undermining over all risk

– Fire doors may be used in escape ways– No risk for injuries like for WTD


Types of watertight doors

• Different type of doors used– Normal WTD below bulkhead deck– Light WTD with reduced scantlings, other wise like normal WTD– Semi-watertight doors: to be used with GZ range only, not below immersion line– Fire doors

• Use of doors during navigation may be different– WTD always closed– Semi-WTD and fire doors may be kept open


Cold rooms

• Cold room panels and doors sustain a water level up to 3.5m• No change to the design is expected• Cold rooms should be assumed watertight if located just below bulkhead

deck and above• small influence, more heel, but less draught, Effect on index ship specific


Design to keep WTD closed

• All damage stability calculations are based on closed water tight doors• Operational needs are not considered during design• Layout of the vessel is in conflict with operational needs• Many ships have exemptions to have WTDs open during navigation

Many 3-zone damagesare not

survivable


Design to keep WTD closed

• Design can be adapted to keep WTDs closed• Example “Laundry”:


Design to keep WTD closed, examples

Workshops in one compartmentMultiple lifts to access provision roomsLaundry arrangement on

two decksIn one compartment


Cruise vessels vs Ropax

• Focus in on cruise vessels in WP1-3• Some items are also valid for ropax

– cross flooding through ducts in large dry tanks

• Ropax have significant differences for subdivision– No subdivision on bulkhead deck– Very little non-watertight boundaries below car deck– Different design constraints lead to different optimum solutions

• Design impacts shown for cruise vessels to be validated for ropax


Conclusion

• General– FLOODSTAND was a very exciting project, although resulted from a merger of

2 proposals• FLOODCONTROL (WP1-3) : focus on flooding inside the vessel• ISTAND (WP4-6): focus on the behaviour of the damaged ship

– Unfortunately too little interaction between both parts• Results

– Full scale tests of doors very helpful to understand flooding process– Valuable information to improve SOLAS2009 calculations– Vulnerability calculations very helpful to alert the crew during operation– more reliable input data for time domain calculations

• The way ahead– Results to be included in EN by SLF– Designer and operators need to consider watertight integrity and operational

needs at an early design stage.– Design ships to keep that allows to keep WTD closed at all times.

A huge safety improvement


Thank you

Questions ?

eu project floodstandfloodstand.aalto.fi/info/examples/workshop_presentations_0702201… ·...

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