What Leonardo da Vinci machine used paddles to move a boat without oars?

Leonardo da Vinci designed a paddle-wheel boat that moved through water without ordinary oars.

His drawings show a boat fitted with paddle wheels turned by mechanical gearing and human operators. As the wheels rotated, their broad paddles pushed against the water and produced forward motion. The concept belongs to Leonardo’s wide-ranging investigations of machines, water, and useful power transmission.

A paddle-wheel boat is not the same as a steamship. Steam-powered paddle steamers became practical much later, after developments in engines and marine engineering. Leonardo’s proposal relied on people turning the mechanism, so it was a mechanical boat concept rather than a powered vessel in the modern industrial sense.

The design also illustrates why Leonardo’s notebooks can be misleading if treated as a catalogue of completed products. Many drawings record proposed mechanisms, and surviving evidence does not establish that this boat was built or operated successfully.