Leonardo da Vinci designed a paddle-wheel boat using rotating wheels instead of oars for propulsion.
The concept used paddle wheels mounted beside the hull. As the wheels turned, their blades pushed against the water and drove the boat forward. A crank and gear arrangement could transmit the crew’s effort to the wheels, allowing several people to work the mechanism in a coordinated way.
Leonardo’s interest in paddle propulsion formed part of his wider study of watercraft, gears, and force transmission. Paddle wheels can provide propulsion without repeatedly lifting oars from the water, although they add mechanical complexity and can be vulnerable to damage. The design therefore shows both an attempt to improve efficiency and the engineering trade-offs involved.
Leonardo’s drawing should not be confused with a modern steamboat. His boat relied on human power, not an engine or steam pressure. Paddle-wheel propulsion was also not exclusively Leonardo’s invention; related concepts appeared in earlier cultures and later became important in powered boats.