Abstract: Disclosed is a device that protects inboard/outboard motors (up to 250 horsepower) from damage and simultaneously provides an underwater hydrofoil that both helps prevent inboard/outboard motor damage and is specifically designed to improve the efficiency of an outboard motor and the speed and ride of a boat. In one embodiment, an underwater hydrofoil, skeg enclosure, skeg protector and lower-unit protector are combined into a single unit that protects the skeg, the propeller and the lower unit of an inboard/outboard motor while simultaneously improving the efficiency of an inboard/outboard motor and the speed and riding qualities of a boat using that inboard/outboard motor.