What propulsion system did Leonardo da Vinci propose for a paddle boat?

Leonardo da Vinci proposed paddle wheels as the propulsion system for a paddle boat.

His sketches show a vessel driven by rotating wheels fitted with paddles. As the paddles pushed against the water, they would produce forward motion, an idea later used extensively in paddle boats and paddle steamers.

Leonardo’s proposal was mechanical rather than steam-powered. His drawings include arrangements involving cranks and gearing, but there is no evidence that he built a full-size working paddle boat.

The concept should not be confused with a modern screw propeller. Paddle wheels act on the water from the sides or rear of a vessel, while a propeller uses rotating blades beneath or behind the hull. Both systems convert rotational motion into thrust.