A Modified Static Equivalency Method for Roll-on/Roll-off Vessels

摘要

A refined static equivalency method (SEM) for assessing damaged stability is presented, based on the accumulation of water on the vehicle deck of roll-on/roll-off (RO/RO) vessels. For each damage case, a critical water head on the vehicle deck can be calculated that causes the ship to heel statically to a point of no return. This static elevation is compared with the dynamic one, induced by waves, which has been obtained theoretically. This enables in turn the knowledge of the critical sea state, described by significant wave height H_s, and calculating the factor s = F(H_s), essential in the new subdivision regulation, based on distribution of sea states at the moment of collision. The critical H_s for each damage case represents the capsizal resistance of damaged RO/RO vessels. The paper explores the theoretical boundary stability curve along with the uncertain zone and shows good agreement with the previous and new experimental results. Based on this analysis, new expressions for the critical relative wave height and critical sea state were derived.