What type of machine did Leonardo da Vinci design to power boats using paddle wheels?

Leonardo da Vinci designed a paddle-wheel boat powered by mechanical paddle wheels.

His studies show a boat whose paddles would push against the water to produce forward motion. Gears and cranks were intended to transmit power from people operating the mechanism. The concept offered an alternative to oars and sails, especially for maneuvering on rivers and other relatively sheltered waterways.

Leonardo’s boat belongs to a wider group of Renaissance transport experiments. He investigated water resistance, propulsion, and mechanical transmission, but there is no conclusive evidence that he built and tested a full-scale paddle-wheel vessel. Paddle wheels became practical in later centuries when engines provided continuous power.

The design should not be called a steamboat. Leonardo had no steam engine capable of powering it. Its proposed energy source was human effort, transferred through a mechanical system to the wheels.