Saildrive
An inboard engine that drives the propeller through a leg passing straight down through the hull, instead of a shaft.
A saildrive combines an inboard engine with a gearbox leg that passes vertically through the hull, like the lower unit of an outboard. It eliminates shaft alignment, the stuffing box, and prop-shaft vibration, and lets the engine sit further forward. The leg is sealed to the hull with a large rubber diaphragm that manufacturers require replacing every seven years or so, and the aluminium leg needs its own anodes and careful antifouling. Most modern European production boats, including the Hanse 315, use saildrives; older boats such as the early Nonsuch 30 used them too.