Investigation of the influence of propeller loading on a ship rudder in the bollard (J=0) condition

The results of tests on a rudder operating downstream of a propeller are presented. The tests were carried out in an open laboratory. The tests were therefore carried out at true zero speed. This corresponds to an advance ratio of J=0 or bollard pull condition. Performance comparisons were made for seven rudder angles between -45 degrees and +45 degrees at two rates of revolution 1160 and 1460 rpm. The tests consisted of a series of parametric studies into the effect of longitudinal and lateral distance between the propeller and rudder. A five-component strain-gauge dynamometer was used to measure lift, drag and three moments on the rudder. A rotating strain gauge dynamometer measured the developed thrust and torque of the propeller. Results are presented in the form of non-dimensional coefficients lift (C subscript L), drag (C subscript D). The influence of rudder on propeller performance is given in terms of non-dimensional thrust (K subscript T) coefficient and torque (K subscript Q) coefficient. The results provide data for detailed rudder design, for numerical modelling of the rudder and propeller interaction problem and for use in low speed manoeuvring simulations.