Most of the research work on cold region marine technology so far has been directed toward ice impact loads on structures and propellers and methods of reducing the resistance of ice-transiting ships. Very few studies have been made on the hydrodynamic performance of propellers in a mixture of ice fragment and water. This paper presents a method of predicting the performance of marine propellers in ice-clogged channels by means of model tests in a mixture of water and plastic pieces. The difficulties in experiments caused by the high impact loads of plastic material have been overcome by the introduction of a new method of making model propellers and by the development of a new propeller dynamometer. The results of tests with four propeller models are presented. The importance of disregarding the scaling of the modulus of elasticity and the strength of plastic material to that of natural ice is considered. The laws of similitude are discussed.