SHIP DESIGN USING PROBABILISTIC DAMAGE STABILITY RULES-A SENSITIVITY STUDY

Publisher Summary This chapter addresses the calculation of the Attained Index A. The first part considers the variation of A with the degree of details in the modeling of the compartmentation. The exemplified vessel is a recently built Danish ferry and both the SOLAS Part B-1 and the SLF 43/3/2 proposals are applied. The contributions from single and multiple compartment damages are identified. The reason for the different predictions from the two calculation procedures is discussed. The conclusions contain guidelines for the level of details needed in the geometrical definition of the vessel to predict the Attained Index A with acceptable accuracy. The current IMO resolutions contain two different probabilistic damage stability regulations: A.265 for passenger vessels and SOLAS Part B-1 for dry cargo vessels. However, ongoing harmonization studies as those presented in the IMO documents SLF 42/5 and SLF 43/3/2 aim at one single damage stability rule applicable to all kinds of ships. Such a harmonization requires due consideration of both the calculation of the attained index describing the probability of survival, and specification of a suitable minimum level, taking into account the consequences of loss of the vessel. The second part of the chapter considers the variation of the Attained Index A with change in main parameters in the preliminary design phase. The main conclusions are that the height of the main deck may influence the attained index by up to 60 per cent, whereas the length of the machinery room can change A by up to 20 per cent.