Abstract: This invention relates to an outboard motor assembly and servo mechanism therefor, and particularly to one in which the motor, propeller drive shaft and propeller can quickly and easily be raised as a unit to locate the propeller at a position where the propeller will not cause cavitation at very slow speeds and where it will reduce the draft required for the boat on which the motor is mounted, but at the same time permits immediate lowering of the propeller to a position for high speed operation when deeper water is reached. The above is accomplished by providing an auxiliary transom adjacent the main transom which is mounted for limited reciprocal movement in substantially a vertical direction by a servo mechanism, preferably under the control of the operator of the boat. This enables the boat propulsion means to be quickly changed from a position for slow speed operation to a position for high speed and vice versa.