Abstract: A technique for testing marine propellers by analyzing the type of cavitation appearing on a reduced-scale model of the associated actual ship, and thereby obtaining data for correcting imperfections in propeller design, and for reducing pressure fluctuations at the lower sternframe portion of the ship. The technique inculdes simulating the water flow acting on the propeller. The procedure is characterized by adjusting the denominator of the cavitation index of the model in order to achieve an approach in the tests to equality between the cavitation indices of the model and the actual ship. This adjustment is achieved in the tests by increasing the towing speed or the propeller revolution rate of the model until the above-mentioned equality of cavitation indices is reached, ignoring the influence that the actual component of the wake speed due to wave formation might have in the tests.