What Leonardo da Vinci device used paddle wheels to propel a boat through water?

Leonardo da Vinci designed a paddle-wheel boat that used rotating paddles to propel a vessel through water.

His notebooks contain several studies of paddle mechanisms, including designs in which cranks and gears transfer human power to wheels mounted at the sides of a boat. The paddles push against the water and create forward thrust, much like later paddle steamers, although Leonardo’s concept relied on people rather than a steam engine.

The design was part of Leonardo’s wider work on canals, locks, mills, and hydraulic machines. It should not be called a steamboat: steam power was absent, and the drawings do not demonstrate a completed working vessel. The mechanism also differs from a propeller, which pushes water backward through rotating blades placed behind or below a boat.