Motions and loads of a trimaran travelling in regular waves

Comparisons are carried out between the wave-induced motions and loads of a trimaran travelling at various forward speeds in regular head waves obtained using three-dimensional fluid-structure interaction models, treating the vessel both as rigid and flexible body. For the rigid body analysis only, both pulsating and translating, pulsating source distributions over the mean wetted surface are used. The latter is more suitable for fast vessels, due to the speed dependent Green's function. Only pulsating source distribution is used for the hydroelasticity analysis. Differences are observed between heave and pitch motion RAOs predicted by these two methods, for low as well as relatively high forward speeds of operation, arising in the main from the interaction between main hull and outriggers and the pitch resonance. The concept of the trimaran requires estimation of longitudinal loads, such as vertical bending moment, as well as transverse loads, such as prying moment at the connection of the crossbeam to the main hull, in order to evaluate the dynamic response of the structure in waves. The predicted vertical bending and prying moments from the three analytical models show differences, especially at relatively high forward speeds.