Sail Drive

A sail drive is a transmission system for a boat whose inboard engine has a horizontal output shaft. The sail drive’s input shaft is, therefore, also horizontal. That input shaft is geared to drive a vertical intermediate shaft extending downward through the hull. The intermediate shaft is then geared to drive a horizontal propeller shaft mounted on a skeg outside the hull.

Electric sail drives are also available from manufacturers like Torqeedo and Kräutler.