What watercraft did Leonardo da Vinci design with paddle wheels to move across water?

Leonardo da Vinci designed a paddle-wheel boat to move across water.

His sketches show a boat propelled by rotating wheels fitted with paddles. Cranks and gears would transfer motion from the operators to the wheels, pushing water backward and the boat forward. The concept reflects Leonardo's interest in replacing or supplementing sails and oars with mechanical power.

The design belongs to a broader group of Renaissance studies of waterways, boats, locks, and hydraulic machinery. Leonardo did not have a steam engine or internal-combustion engine to power the vessel, so his proposal depended on human operators turning the mechanisms. It was a design concept rather than a documented successful voyage.

A paddle-wheel boat should not be confused with a modern motorboat. Paddle wheels are a propulsion method, not an engine type, and they were later used on steamships after reliable engines became available. Leonardo's drawing is significant because it anticipates mechanically assisted navigation while remaining within the technological limits of his period.