3.2 Tuning Test

　

 Drifting distance HD, drifting direction μD, average yaw rate γave, average ship speed ratio Uave /U0, and average oblique angle βaveduring 35deg turning motion for full load and ballast conditions are shown in Fig. 6. Those values in calm water conditions are also shown in Fig. 6 except for drifting distance HDand drifting direction μD. Definition of drifting distance HD and drifting direction μD are explained in Fig. 7. Drifting distance HD is defined as distance between successive ship positions in which wave encounter angle χ is equal to -90deg. Drifting direction is defined as offset angle from wave propagating direction to moving direction of positions of a ship in which wave encounter angle χ is equal to -90deg.