|Title: EMSA Study on Damage Stability of ROPAX Vessels|
|Written by: Stefan Krüger, Hendrik Dankowski, Petri Valanto|
|in: EMSA Research Project, Hamburg 2009|
Abstract: Two new RoPax ships were designed to meet the requirements of the new probabilistic SOLAS 2009 damage stability standard. The safety levels attained by the different ship damage stability rules to these two ships were determined with Monte Carlo simulations. For both ship designs the safety level presented by the SOLAS 2009 Reg. B-1 rules clearly drops down to a significantly lower level than that presented by SOLAS 90 Reg. II-1/8 standard together with the Stockholm Agreement. The hydrostatic calculations show that the smaller ship suffers from a general lack of stability, but the designed subdivision is reasonable. The larger ship has a sufficient level of stability, but the ship would capsize or sink rapidly also in calm water, if the lower hold got damaged. In general the numerical simulations give a good picture of the ship heeling and vehicle deck flooding process, but they predict a somewhat too low survivability for these two vessels. Typical damage cases were chosen for the model tests, which gave the following results: The smaller ship capsized already at significant wave height Hs 3.0 m. In some other damage cases ship is expected to capsize in much lower waves, also when there is no water on the vehicle deck. Excluding the lower hold damage the larger ship would probably survive some likely damage cases in a sea state of Hs 4.0 m. Altogether the present investigation of the two RoPax vessels shows that in the framework of the new probabilistic damage stability rules (SOLAS 2009) for passenger ships built from January 1, 2009, it is possible to create ship designs with significant deficits with regard to safety. In view of this it is difficult to come into any other conclusion that the ship stability required by the SOLAS 2009 rules is not likely to be sufficient in all cases. Corrective action should be taken to amend the SOLAS 2009 rules. A suggestion for the direction of future work is given.