Abstract: The invention relates to the adaptation of a Mazda RENESIS rotary engine to use as a marine vessel propulsion system. It is an object of present invention to enhance the power and torque bands of the rotary engine and shift them to the midrange of engine speeds that are most applicable in direct drive systems. Peak torque of 300 ft-lbs. at 3750 rpm and Peak power of 325 hp at 5800 rpm have been realized. The invention comprises various engineering developments to increase performance. These developments include modifications to standard engine components such as intake and exhaust manifolds as well as addition of customized performance tuned components including a turbocharger, an aftercooler, an oil cooler, and an engine control management system. Improvements to engine mounting and power transmission mechanisms are also described.