What Leonardo da Vinci invention used a chain and paddle wheels to move a boat against a current?

Leonardo da Vinci's paddle-wheel boat used a chain and paddle wheels to move against a current.

Leonardo studied paddle propulsion as part of his extensive work on water machines. In his designs, human power turned mechanisms that transferred motion through gears or chains to paddle wheels. The rotating paddles pushed water backward, producing forward movement for the vessel.

The idea was not a modern steam-powered paddle steamer. Steam engines and practical powered paddle ships appeared much later, especially during the Industrial Revolution. Leonardo's sketches instead explored how mechanical transmission could make rowing more efficient and continuous. His watercraft studies also included pumps, locks, and canal machinery, so individual drawings are sometimes incorrectly treated as complete, tested boats rather than engineering concepts.