Leonardo da Vinci proposed paddle wheels as the propulsion method for a boat.
His sketches of paddle boats show rotating wheels fitted with boards or paddles that would push against the water. A mechanical system of gears, cranks, or treadle-like controls was intended to turn the wheels. The arrangement resembles the principle later used by paddle steamers, although Leonardo’s design was powered by people rather than steam engines.
The proposal belongs to Leonardo’s broader study of transport, water movement, and machines. It was not a steam-powered vessel, because steam engines were developed centuries later. It also was not simply an ordinary rowing boat: the paddles were attached to rotating wheels rather than handled individually by rowers.
The exact performance of Leonardo’s boat is uncertain because the surviving drawings are designs rather than records of a completed working craft. Its historical importance lies in recognizing that repeated mechanical motion could be converted into useful thrust on water.