What kind of boat did Leonardo da Vinci design with paddle wheels for propulsion?

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

The concept appears among Leonardo’s studies of waterways and mechanical power. Instead of relying only on wind or oars, the boat would transmit motion from a human-powered mechanism to paddle wheels mounted along its sides. The paddles would push against the water and move the vessel forward.

Leonardo did not invent the general idea of using paddles on boats, since paddle propulsion had earlier precedents. His contribution was to develop detailed mechanical arrangements and apply them to a practical-looking vessel. The drawings show his characteristic interest in gears, shafts, and coordinated movement, but they do not establish that the boat was constructed or successfully tested.

This design is sometimes described as a steamboat, but that label is inaccurate. Leonardo had no steam engine driving it. Its proposed power source was mechanical, making “paddle-wheel boat” the precise description.