Abstract
We investigated the nonlinear effect and forward speed effect of hydrodynamic forces for the longitudinal motions of trimarans. To discuss the nonlinear effect and forward speed effect of hydrodynamic forces, we employed the nonlinear strip method and linear Rankin panel method respectively. Results show the nonlinear strip method is more effective than linear strip method to predict the longitudinal ship motions in the case of Fn=0.2, and the results of the longitudinal ship motions by using Rankin panel method give better agreement with the experimental ones in the case of Fn=0.4 and 0.6. It is confirmed that the phase difference of restoring forces acting on the main hull and side hulls affects the restoring force of trimarans.
