Abstract: A boat is disclosed having a conventional inboard motor operatively connected to a primary propeller on the exterior of the boat. A hydraulic motor is operatively connected to the boat in the proximity of the primary propeller. A hydraulic circuit including a hydraulic pump is operated by the inboard motor and is connected to the hydraulic motor for actuating the hydraulic motor. An electrically operated solenoid valve is imposed in the hydraulic circuit to selectively by-pass hydraulic fluid in the hydraulic circuit away from the hydraulic motor. The hydraulic motor is pivotally connected to the boat so that when in a first position, it will drive the boat forwardly, and when in a second position, it will drive the boat rearwardly. Conventional controls are provided to withdraw power from the primary propeller when the hydraulic motor is in operation.