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RP592 (RP564) INVESTIGATION INTO THE SAFETY OF RO-RO PASSENGER SHIPS FITTED WITH LONG LOWER HOLDS – PHASE II © Andrzej Jasionowski and Peter Blackwood / Safety At Sea Ltd / UK Project Team Piotr Dolebski / Safety At Sea Ltd / UK Pöyliö Esa, Aarno Liimatta / Deltamarin / Finland December 2007 – March 2009 Funded by UK and Netherlands 31 st March 2009

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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Two designs ParameterValue Ships length overall 182.6m Ships Length Between Perpendiculars 166m Ship breadth (moulded) 27.2m Depth (moulded) 14.2m Draught (design) 6.0m Number of Passengers 1000 People R = 0.74

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Ship 1 & 2 Arrangement

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Ship 1 & 2 Machinery Ship 1 Ship 2

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Commercial feasibility Ship 2 offers more Ro- Ro space (though higher GM required to comply with SOLAS2009)

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Systems un-availability Ship 2 has superior systems protection w.r.t. Ship 1! Ship 1 Ship 2

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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s formulation Adoption of GZ max = 0.12 for RoPax ships has been a historical error. Conventional ships RoPax

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s formulation Maximum reduction of ~16.8% to index s depending on the GZmax. Note that no reduction will apply when GZmax = 0 or GZmax > 0.25.

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s formulation Actual variations to s factors for different flooding cases …

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s formulation Maximum possible reduction to A would be 16.8% reduction to s, applicable to 13.5% possible flooding cases, so = ~2%. When accounting for actual reduction to s and p i for each flooding case, the reduction amounts to A = 1.07%.

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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Ship 1 SA is the most stringent stability requirement (for DS). Note that SA can be met by enforcing A DS =R

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Ship 2 SA not MET!!

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Ship 1 & 2 Ship 1 (designed to A DS =0.9R) does not comply with Stockholm Agreement (SA) at deepest draught DS slightly. Ship 2 does not comply with SA by a big margin! It simply is prohibitive from viewpoint of SA. Is Ship 2 so much worse than Ship 1?

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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Ship 1 & 2 Simulation performed for Worst Case SA and a KG value. Survivability assessed for Ship 1 and 2.

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Worst SA case, Ship 2

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Immediate Capsize! This just verifies that attempt to seek compliance with SA by experiment would also likely fail at reasonable KG.

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Vulnerability - UGD … it seems that actually the vulnerability of both Ships, both of which meet MSC216 Reg 6-1, i.e. A DS =0.9R, is of the same level overall … Note that this is result averaged according to w i for all draughts. … the vulnerability implies probability of capsize within given time after collision. 25% implies that of every 4 statistically possible collisions, one would lead to rapid capsize say in ~120minutes

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Monte Carlo Simulations A series of damages are randomly chosen and numerical simulation for 40minutes is performed … The result is a series of capsizes within simulation time! Make histogram of these times and derive CDF ….

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Vulnerability – Numerical Simulations This just verifies through independent technique that the vulnerability of these two ships is of the same level despite SA implying vast difference! Note that this is result for DS only

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What is the meaning? (1)The level of survivability is the same for both ships: SOLAS2009 UGD or Numerical Simulation (2) So the level of survivability would also be the same for these KG. However according to SA only Ship 1 is viable! Hence – SA is not consistent!

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What is the meaning? But what about the worst flooding case of Ship 2 that failed SA? How can rapid capsize be accepted? Well, according to MSC216, as many as 18.7% of cases which have ZERO stability is acceptable … A further % of cases would be overcome by some waves Only 67% would survive up to 4m sea states after a collision … so, this capsize is one of 18.7% that are allowed under SOLAS anyway …

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What is the meaning? Note that this is result for DS only This level of survivability can be achieved by ensuring that A DS =R The difference between SOLAS09 Reg 6-1 and SA is about 20% reduction in vulnerability. But it does not mean that all feasible flooding cases could be survivable by a SA- compliant ship. Far from it.

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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Revise MSC216 (82) Reg 7-2-5 and 6

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Revise MSC216 (82) Reg 6-1 and Reg 7-1

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Revise MSC216 (82) Reg 6-2-3

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SOLAS 1974 Chapter II-1 assumedThe subdivision of passenger ships into watertight compartments must be such that after assumed damage to the ship's hull the vessel will remain afloat and stable. any feasibleThe subdivision of passenger ships into watertight compartments must be such that after any feasible damage to the ship's hull the vessel will remain afloat and stable.

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Outline Design development Impact of s formulation on A Impact of standards on KG limits Level of survivability (vulnerability) Recommendations Conclusions

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Two different ships were designed to SOLAS09. Neither complied with SA, and hence SA is the most stringent standard in force. Impact of appropriate correction to s formulation amounts to some 1% reduction of index A. The level of survivability between both designs was found to be the same, despite vastly different level in the lack of compliance with SA (vastly different KG limits). Hence, the level of survivability implied by SA is not consistent. The level of survivability implied by SA could be achieved by ensuring A DS =R. Neither of standards prevents catastrophic loss of stability. Goals of SOLAS convention are revised to amend this serious ship vulnerability.

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