What watercraft propulsion system did Leonardo da Vinci design using large paddle wheels?

Leonardo da Vinci designed a paddle-wheel boat propelled by large wheels turning in the water.

The sketches show a vessel in which people operate a mechanical system connected to paddle wheels. Instead of relying only on oars or wind, the design concentrated human effort into rotating wheels that pushed against the water. Leonardo explored the idea while studying transportation, hydraulics, and mechanical power.

The boat was a proposal rather than a documented successful vessel. It is sometimes loosely called a steamboat, but Leonardo's design did not use steam power. It also differs from later paddle steamers, whose wheels were driven by steam engines. Leonardo's concept belongs to the long history of attempts to replace individual oars with mechanical propulsion.