Saildrive

An inboard-engine drive unit whose geared leg passes through the hull and carries the propeller.

The engine is mounted inside the vessel and drives through a gearbox and vertical or inclined leg, avoiding the long exposed shaft and separate stern gland of a conventional shaft drive. The installation commonly uses a flexible diaphragm or seal between the saildrive and hull.

Gear oil, seals, anodes, propeller, cooling-water passages and the hull diaphragm require manufacturer-specified inspection and replacement. Galvanic corrosion, fishing-line damage and water contamination of oil can lead to serious failure, and electrical bonding arrangements must follow the particular installation.

Lower gears in the saildrive leg turn the drive through approximately a right angle to the propeller shaft. Electrical isolation and compatible anodes are important because an immersed aluminium leg can be vulnerable to galvanic and stray-current corrosion.

Terms with the same meaning:
Sail Drive