This paper describes procedures for predicting the growth rate of fatigue cracks in ship structure welds under sea-wave loading as well as the stress corrosion cracking behaviour of steel in marine structures. A computer program which can be applied to assess the residual life-time and to estimate the probability of failure of marine structures under wave action is presented. The main objective of applying this program is the development of an optimal inspection and maintenance policy for marine structures. Moreover, the presented computer program is of value to insurance companies in order to assess the safety level of a marine structure and consequently to estimate their financial risk