Abstract: A transmission for connecting a propeller to an engine having a crankshaft. The transmission has an output shaft and a propeller shaft and a belt connecting the output shaft to the propeller shaft. The output shaft has a pulley connectable to the crankshaft of an engine and a pulley driven propeller shaft is supported on the frame by means of a flange having bolt holes supported in a circle having a center offset from the center of the output shaft so that the flange can be connected to the frame in any position and bolted in place. The bolts can be removed and the flange rotated to different bolt holes thereby swinging the center of the propeller shaft around the center of the bolt holes to tighten the belt. An improved coupling is provided for connecting the drive pulley to the engine.