A V-drive is a power transmission system for boats that consists (usually) of two gearboxes, two drive shafts, and a propeller.
Whereas the conventional arrangement sites the engine with its gearbox aft, driving the propeller shaft directly, in a "V-drive" layout, the engine is reversed, to have the gearbox in front. This primary gearbox typically drives a short shaft forward to a transfer gearbox which reverses the transmission to the main tailshaft which is directed rearwards at a "V" angle to the propeller itself.
A variation of the two-shaft V-Drive layout is the "Close-Coupled V-drive" whereby the engine is still mounted "back-to-front", but the gearbox incorporates an output flange that has already been reversed. This system obviates the need for any short primary shaft.[1]
Counter-intuitively, a V-drive system will not necessarily mean that the engine is sited further rearward; the whole engine/transmission may be sited forward than in a conventional arrangement.