This paper deals with the resistance and self-propulsion tests in still and rough waters on a series of three geometrically similar models for a super tanker. The results of resistance tests in still water show that Froude's method of calculating a ship's resistance has in principle lost none of its applicability if a proper friction line is chosen. According to the propeller open tests and self-propulsion tests there will exist a slight scale effect on the smaller model propeller. The results of tests in waves show that virtual mass coefficient is almost constant independently of length of models, and that there are little scale and wall effect in such a range of model length, model speed and wave conditions as in these experiments.