Leonardo da Vinci’s paddle boat was a proposed vessel propelled by paddles turned through a rotating mechanical system.
Leonardo’s notebooks contain several studies of boats and water propulsion. In the paddle-boat concept, human or mechanical power would turn a shaft connected to paddle mechanisms, pushing water backward and moving the vessel forward. The arrangement sought to convert rotary motion into useful thrust.
The design is often compared with later paddle-wheel boats, but Leonardo’s drawings do not establish that a full-scale working vessel was built. They instead show his effort to analyze propulsion through gears, shafts, and repeated motion. His watercraft studies were part of a much wider interest in transport and hydraulic engineering.
A paddle boat is distinct from a sailboat, which relies primarily on wind, and from a submarine, which is designed to operate below the surface. Leonardo’s concept also should not be confused with his canal-lock work, which addressed water levels rather than propulsion.