Which Leonardo da Vinci invention used rotating paddles to propel a boat?

Leonardo da Vinci’s paddle boat used rotating paddles to propel a boat.

Leonardo drew a boat powered by paddle wheels rather than by oars or sails. A person or group of people would turn a mechanism connected to the paddles, transferring rotational motion into forward movement through the water. The idea belongs to his wider investigations of gears, cranks, and hydraulic machinery.

The paddle boat was a design, not a documented powered vessel that Leonardo built and operated. Its principle resembles later paddle-wheel propulsion, but it should not be described as a steamship: Leonardo had no steam engine driving the craft. Human power was central to the concept shown in the drawings.

It is also different from a traditional galley. A galley uses oars moved directly by rowers, whereas Leonardo’s proposal uses a mechanical transmission and rotating paddles to convert effort into thrust.