Combining the features of inboard and outboard engines
A stern drive was the name reserved for the lower unit of an inboard-outboard engine, but it is now commonly applied to the entire hybrid system. It consists of a conventional inboard engine attached through the transom to
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| A 315-horsepower gasoline engine built by General Motors, marinized by Volvo, and mated to a Volvo SX stern drive |
what is essentially the lower unit of an outboard motor.Stern drives, also known as inboard-outboards, are best suited to hulls between 16 and 25 feet (4.8 to 7.6 m) in length. They combine the advantages of a powerful inboard engine with the handling and steering properties of an outboard motor. Neither rudder nor trim tabs are needed because the outdrive swings from side to side and tilts up and down.The engine is placed immediately forward of the transom, and a horizontal driveshaft pierces the transom above the waterline to contact the vertical shaft of the outdrive. The upper part of the outdrive incorporates a clutch and gearbox.The entire outdrive may be tilted up for towing on a trailer or when the vessel is beached. In the up position it will also clear the water and avoid fouling and corrosion.Maneuvering with a stern drive is quick and positive, and another advantage is that the inboard engine is more fuel-efficient than an outboard of comparable power.
