Leonardo da Vinci designed a paddle boat using rotating paddles to push it forward.
His notes include several ideas for mechanically assisted water transport. In the paddle-boat concept, human operators turn cranks that drive paddle wheels through gears. The paddles press against the water, producing thrust without relying on wind or a conventional sail.
Leonardo's proposal belongs to a long history of paddle propulsion, which appeared in different forms before and after his lifetime. Ancient and medieval inventors also considered oars and paddle mechanisms, while commercially successful steamboats with paddle wheels emerged only after steam power became practical in the eighteenth and nineteenth centuries.
The drawing should therefore be understood as a mechanical concept, not a proven Renaissance steamboat. Leonardo did not have a compact engine capable of powering the vessel. His importance lies in analyzing how gears could convert human effort into a repeated rotary motion for transportation on water.