In this study, numerical prediction of a ship maneuvering in calm water area with varying water depth are carried out to investigate the shallow water effect on ship's maneuverability. The system based prediction approach is adopted by establishing a 3 degrees of freedom (DOF) mathematical model based on the modular concept. The lateral added mass and added moment of inertia are obtained by a strip theory method. Other coefficients including the longitudinal added mass, the maneuvering derivatives and the coefficients for estimating the resistance on the hull in straight moving, the propulsive force by the propeller, steering force by the rudder, and the interaction between hull-propeller-rudder are obtained by commonly used empirical and semi-empirical formulae, or directly from published data. The MOERI KVLCC2 tanker vessel is selected as the sample ship. The free running manoeuvers in deep and shallow water at different water depths are simulated and compared with available experimental results for validation. A special simulation case of stepped bottom varying from deep water to shallow water which resembles the real situation in harbor area is also carried out. The shallow water effects on ship's maneuverability are discussed and recommendations on steering operations in shallow water are given.
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