What type of boat did Leonardo da Vinci design with paddle wheels powered by people?

Leonardo da Vinci designed a paddle-wheel boat powered by people turning mechanical cranks.

The concept used rotating paddle wheels to push against the water and move the vessel forward. A crew would operate the mechanism through a system of gears and handles, transferring human effort to the wheels. Leonardo’s studies of watercraft explored how mechanical power could improve movement on rivers and canals.

The design was not a steam-powered boat, because steam engines did not yet exist in Renaissance Europe. It also was not a conventional sailing galley, whose main propulsion came from sails and oars. Leonardo’s paddle-wheel concept belongs to a long history of attempts to replace direct rowing with mechanical transmission.