Semi-Empirical Assessment of Long-Term High-Frequency Hull Girder Response of Containerships

High-frequency responses extracted from measurements onboard a Panamax containership and a post-Panamax containership were assessed by calculating cumulative fatigue damage. Responses were superimposed on damage obtained from numerical rigid body seakeeping calculations. Numerical analyses accounted for duration of measured seaways, ship headings relative to prevailing directions of encountered seaways, and ship forward speeds. Only the post-Panamax containership on its Far East route encountered relatively mild seaways, resulting in relatively low damage ratios. To represent worldwide service routes, measured high-frequency contributions were extrapolated to obtain high-frequency response of both these ships operating in severe North Atlantic and North Pacific seaways.