Long term wave data and their influence on design values of wave loads of ships

The design values of wave bending moments are of critical importance to ship structure design. When direct design methods are used for ship design, especially for ships beyond rules, wave data, in which ships will sail in their lifetime, must firstly be well recognized and rationally selected. In this paper, five sets of wave data form different sources are analyzed. Based on the scatter diagram of these wave data and with linear and nonlinear strip theories, the long-term wave-induced and combined bending moments including slamming components are predicted for a large containership. The results are compared with the design values in IACS UR-S11 and the influences of wave data on design values of wave loads are analyzed. Finally, some suggestions are made for direct design calculations of wave loads of ships.