Collision Damage Statistics and Probabilistic Damage Stability Calculations in Preliminary Ship Design

The recent IMO Resolution MSC 19(58) points towards a more rational way of obtaining subdivisions in ships to ensure a sufficient stability in damaged conditions.In the preliminary phase of ship design it is important to know how the attained subdivision index and the possible oil outflow in a collision are influenced by the actual positions of the watertight bulkheads. This information should be given in form of sensitivity factors yielding the change in attained index, subdivision and oil outflow for specified changes in the position of user-defined bulkheads.In the paper such a procedure will be described. The formulation is quite general implying that future improvements in the damage stability regulations can be easily implemented.Furthermore, information of oil outflow from damaged cargo tanks is included. By that, both the probability of zero outflow, average hypothetical oil outflow as well as mean local outflow are presented. The procedure can thus be used to compare the environmental damage to be expected from different type of oil tankers in a given collision scenario.