Numerical Simulation of Ship Dynamics for Application in a Weather Routing System

In order to enhance the efficiency and safety of a ship sailing in rough seas, the authors aim to develop a ship dynamic performance system, which can be used to predict ship motion responses, wave loads as well as quasi-mean added resistance. Two-dimensional strip theory discretized by the source distribution method is implemented to calculate Response Amplitude Operators (RAOs) for 6 DOF motion as well as the wave loads for the vertical shear force and bending moment. In addition, the ITTC directional wave spectrum of the short-crested wave adopts the one-hundred years return sea state as the input for testing the sea-keeping performance. Subsequently, we developed a database for a specific ship to realize the relationship between the sea-keeping performance and a combination of wave headings and ship speeds. Since the calculation of hydrodynamic coefficients correspond to the instantaneous hull form below the free surface (draft), the B-spline curve fitting technique based on the fourth order Runge-Kutta method is introduced to describe the relative wave heights together with second order nonlinear forces.