Short term statistics of hydroelastic loads of a containership in head and oblique seas

Vertical bending moment (VBM) is an importantparameter for the structural safety of any sea going ship.Generally, it is expected that ships encounter largest VBM inhead seas. However, when it comes to flexible ships, it is notnecessary that the largest VBM always occurs in head sea. Itcan also occur in oblique waves and high frequency response inwaves with shorter period can be as large as the wavefrequency response or can be even larger. Studies conducted inthe recent past by other researchers has shed some light intothis peculiar characteristics of VBM of flexible hulls.Therefore, it will be worthwhile to further investigate to checkwhether the nonlinear design load calculation of the flexiblehull in head seas will lead to conservative results or should betested for a range of headings with different combinations ofwave period in order to estimate the largest VBM acting on thehull. In this paper, the numerical and the measured VBM of anultra large container ship (ULCS) in low to severe sea states areanalyzed and compared. The effect of speed, significant waveheight, springing and bow flare slamming on the response isstudied. The measured VBM in head and oblique waves arecompared and interesting findings are observed.