What Leonardo da Vinci device used paddles to move a boat through water?

Leonardo da Vinci designed a paddle boat that used paddles to move through water.

His sketches show paddle mechanisms connected to cranks and gears. Turning the cranks would make the paddles press against the water, producing forward motion without relying on ordinary oars. The design reflects Leonardo’s interest in transferring human effort through mechanical systems.

This concept was not a steam-powered paddle steamer. Steam engines and practical steamboats appeared centuries later. Leonardo’s paddle designs were also not necessarily one standardized vessel; they represent related studies of water propulsion. Their importance is that they apply rotary mechanical motion to boat travel in a period when rowing and sailing were dominant.