Leonardo da Vinci designed a paddle wheel to move a boat using human-powered paddles.
His boat studies included mechanisms in which rotating paddles pushed against water to produce forward motion. The paddles could be driven by people turning cranks or operating linked machinery. This approach was intended to make a vessel move without depending entirely on oars or sails.
Leonardo’s design belongs to a long history of paddle propulsion. Paddle wheels were later used on practical boats and became especially important on steamboats in the 18th and 19th centuries. Leonardo’s sketch itself was a proposal, not evidence that he launched a successful powered vessel.
A paddle wheel differs from a propeller. A paddle wheel has visible blades or paddles mounted around a wheel, while a propeller uses rotating blades arranged around a central shaft. Both convert rotational motion into thrust, but they interact with water in different ways.