Experimental Researches on Rudder Performance. (2)

The present paper relates to experimental researches on rudder performance utilizing a free running, self-propelled model.Hardover to hardover steering tests have been carried out on four different balance ratios including the optimum one estimated by turning tests, and it is known that the balance ratio must be selected so as to prevent the abnormally large positive torque which may occur when the rudder is steered from port to starboard.An interpretation for the complicated rudder performance during the turning tests have been tried using the results of behind tests and free model tests. As the results, the resonable values for normal force coefficients have been provided through considering the change of slip ratio of propeller and drift angle of ship, but it remains some problems to be investigated for the center of pressure.