Stability Assessment of a Ship by Applying Risk Analysis Based on the Capsizing Probability

Abstract

The authors proposed a method to assess the stability quality of a ship by the risk analysis based on the capsizing probability of it in wind and waves. This method was already experimentally confirmed to be valid for hard-chine craft when experimental results of the roll damping and exciting moment of the craft were given. In the present paper, the method is applied to conventional cargo ships whose roll damping and exciting moment can be predicted by modern ship motion theories developed in these twenty years. The experimental work on the capsizing probability of cargo ships in waves are carried out to confirm the availability of the method. Six kinds of cargo ships in Japanese domestic service are chosen to calculate the capsizing probability for making the assessment of the stability quality of them in severe sea conditions. These results also show that the method is useful to decide the optimum GM value and the optimum size of bilge keels to keep the sufficient stability quality in design stage.