Leonardo da Vinci sketched a paddle wheel as a ship-propulsion device that could replace oars.
His notebooks contain designs for watercraft driven by rotating wheels fitted with paddles. Turning the mechanism would push water backward and move the vessel forward. The idea applied the same basic action later used by paddle steamers, although Leonardo’s versions relied on human or mechanical power rather than steam engines.
Paddle propulsion could reduce the number of rowers needed and make a vessel’s movement more regular. Leonardo explored several arrangements, including side-mounted and stern-related mechanisms, while studying gears, cranks, and naval engineering.
Leonardo did not invent the general idea of the paddle wheel: ancient and medieval engineers had considered or used paddle-driven craft. His importance lies in the detailed Renaissance designs and mechanical analysis. A paddle wheel also differs from a screw propeller, which pushes water through rotating blades mounted on a shaft.