In this study, the characteristics of thrust and rudder force caused by an outboard engine attached to a small boat at low speed are investigated based on the measured data by fully captive oblique towing model test with outboard engine and its required experimental conditions to obtain them sufficiently are proposed. The range of experimental conditions in propeller advance coefficient, rudder angle and drift angle of boat are determined according to the measured data for a real boat at berthing maneuvers.
From the results of the oblique towing test with outboard engine being in operation, it is confirmed that the test with forward speed should be conducted for several inflow angle for outboard engine which is sum of drift angle and rudder angle and propeller advance coefficient within the range of motion of a real boat at berthing maneuvers. On the other hand, the test with backward speed should be conducted for several combinations of drift angle and rudder angle in addition for the conditions of the test with forward speed. However, the measured thrusts and rudder forces for the two conditions which are line symmetry in the longitudinal direction of towing tank are almost same, therefore one of them can be omitted. Moreover, from the comparison the results of oblique towing tests with outboard engine in being operation and not, it is found that the effects of the operation on rudder force is small, then the rudder force can be obtained from the test with outboard engine not in .
