Leonardo da Vinci designed a paddle boat using a wheel, paddles, and a crank for water travel.
His sketches explore ways to convert human effort into forward motion on water. A person turning a crank would drive paddle mechanisms, pushing against the water and propelling the vessel. The concept resembles later paddle-wheel boats, although Leonardo’s drawing is a design study rather than evidence of a completed working boat.
Leonardo investigated water transport extensively because canals, rivers, and military waterways were important in northern Italy. His notebooks include studies of locks, pumps, boats, and hydrodynamics. He was interested in replacing or supplementing oars with mechanisms that could deliver repeated motion.
The design should not be called a steamship. Steam power was not part of Leonardo’s proposal, and practical steam navigation appeared centuries later. Nor was the machine a submarine: its purpose was surface travel.