Leonardo da Vinci designed a paddle-wheel boat powered by people turning mechanisms inside the vessel.
The concept used paddle wheels to push against water and propel the boat. Human operators would turn cranks or treadle-like mechanisms connected to the wheels, allowing movement without relying on wind. Leonardo’s sketches show how gears and shafts could transfer power from the crew to the propulsion system.
Paddle propulsion was not unique to Leonardo, and practical paddle boats appeared in various forms before and after his lifetime. His importance lies in applying detailed mechanical analysis to a vessel that combined gears, human power, and water resistance.
The design is sometimes loosely called a steamboat, but Leonardo’s proposal did not use a steam engine. It was human-powered. That distinction separates it from the powered paddle steamers developed centuries later.