Abstract: A propeller assembly for mounting on the drive shaft of a motorized water vehicle. The propeller consists of a central hub having a hollow body of circular cross-sectional shape through which exhaust gas from the motor can flow. Integrally formed with the hub are a number of arcuate blades. Each blade has a generally fish-shaped axial cross-sectional shape. In particular, from the leading edge of the blade, the cross-sectional shape increases in thickness until reaching a local maximum at a point near the midchord of the blade and thereafter decreases in thickness until reaching a local minimum. The blade thereafter again increases in thickness along concave surfaces until terminating in a concave trailing edge. The trailing edge of the blades are in communication with the exhaust gas flowing through the hub.