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Saildrive

A geared propulsion leg that carries power from an inboard engine vertically through the hull to an underwater propeller.

The engine is mounted inside the vessel and connects to the saildrive leg, which passes through a hull opening sealed by a flexible diaphragm. Lower gears turn the drive through approximately a right angle to the propeller shaft.

The diaphragm, gear oil, seals, anodes and propeller require maintenance according to the manufacturer. Electrical isolation and compatible anodes are important because the immersed aluminium leg can be vulnerable to galvanic and stray-current corrosion.

Alternative Meanings:
  • 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.