NON-LINEAR PREDICTION OF STEERING PERFORMANCE OF SERIES 60 MODELS

Hydrodynamic forces and moments due to ship motions in the horizontal plane were obtained in tests of 5-foot Series 60 models, and results were used in computations of ship motions in calm water. Non-linear predictions of ship response to rudder action are correlated satisfactorily in comparison with trajectories of a free-running model. Variations of ship maneuvering motions with changes in ship configuration are then examined, and the relationship between maneuvering response and rudder rate is studied, using non-linear computation, to obtain a basis for determining optimum rudder rate for ships of different speed and size. Computed results show that the minimum rudder rate presently allowed is for ocean trading ships of ordinary size and speed; however, this adequate rudder rate could be lower for very large, relatively slow ships, such as super-tankers.