What type of boat propulsion did Leonardo da Vinci design using rotating paddles?

Leonardo da Vinci designed a paddle-wheel boat using rotating paddles for propulsion.

His drawings show a vessel equipped with paddle wheels driven by a mechanical system. As the wheels turned, their blades pushed against the water and moved the boat forward. The idea transferred the familiar action of rowing into a continuous rotary mechanism.

Leonardo investigated the design as part of his broader studies of water engineering and transport. A paddle wheel could, in theory, provide more regular propulsion than individual oars and allow a smaller crew to operate the boat. The surviving sketches do not establish that Leonardo built a full working vessel.

The concept should not be confused with a modern steamboat. Leonardo's design describes mechanical paddle propulsion, but it does not depend on a steam engine. Later paddle steamers used similar wheels while adding engines capable of supplying continuous power.