Leonardo da Vinci designed a paddle wheel for moving boats using water power.
His maritime and hydraulic studies included wheel-driven mechanisms in which paddles pushed against water to propel a vessel. The concept transferred the familiar action of a water wheel to boat transportation: instead of turning a millstone, the rotating wheel produced thrust in the water.
Leonardo’s notebooks contain many proposals for improving water transport, including boats, pumps, locks, and canal machinery. His paddle-wheel designs were not standardized inventions that entered widespread service, and some drawings may represent experimental ideas rather than finished engineering plans. Their importance is that they show him applying mechanical principles to navigation.
A paddle wheel is different from a propeller. A paddle wheel has visible blades or boards mounted around a rotating wheel, while a propeller uses screw-shaped blades turning underwater. Leonardo also studied screw-like devices, but the boat-moving design described here is identified by its paddles and wheel.