V-drive is a propulsion

Marine propulsion

Marine propulsion is the mechanism or system used to generate thrust to move a ship or boat across water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting a motor or engine turning a propeller, or less frequently, in jet...

 system for boats that consists of two drive shafts, a gearbox, and a propeller

Propeller

A propeller is a type of fan that transmits power by converting rotational motion into thrust. A pressure difference is produced between the forward and rear surfaces of the airfoil-shaped blade, and a fluid is accelerated behind the blade. Propeller dynamics can be modeled by both Bernoulli's...

. In a "V-drive" boat the engine is mounted in the rear of the boat and the front of the engine faces aft. Connected to the rear of the engine is the transmission

Transmission (mechanics)

A machine consists of a power source and a power transmission system, which provides controlled application of the power. Merriam-Webster defines transmission as: an assembly of parts including the speed-changing gears and the propeller shaft by which the power is transmitted from an engine to a...

. The first drive shaft connects the rear of the transmission to a gearbox mounted in the centre of the boat. The second drive shaft extends from the gearbox to the rear and out the bottom of the boat to where a propeller is mounted.