Effects of propeller diameters, propeller skew angles and propeller longitudinal positions on self-propulsion factors of a full ship are investigated experimentally and theoretically. Five four-bladed model propellers varying diameters and skew angles were installed on a model full ship, and self-propulsion tests were carried out in the towing tank. The test results varying propeller diameters showed that according to the increase in the diameter wake fraction factor (1-w_T) values increased and values of thrust deduction factor (1-t) and relative rotative efficiency (η_R) were nealy constant. The increse in the skew angle results decrease in 1-W_T and η_R values. The significant effects were seen in the test results varying propeller longitudinal positions. Both 1-w_T, 1-t and η_R values became higher according to the propeller position approached to the rudder, above all variations of 1-t values were superior to the others. Then the increse in the propulsion efficiency became about 3-4%. Test results indicate more attention should be payed not only to the determination of diameter but also to the selection of propeller skew and its longitudinal position. The theoretical calculations based on the ship propulsion theory were performed in order to clarify the interaction mechanics between the propeller and the hull. The effects of diameters and longitudinal positions can be explained well by Yamazaki-Nakatake's theory and skew effects are also clarified by modified Ikehata's theory. It can be concluded that the ship propulsion theory, although it is still under development, now becomes an useful tool of the ship hydrodynamical design.
