Leonardo da Vinci designed a paddle boat with paddle wheels to propel a vessel.
His drawings show rotating wheels fitted with boards or paddles that push against the water. Turning the wheels would create forward thrust without relying entirely on oars or sails, offering a mechanical alternative for moving a boat.
Leonardo studied several watercraft and hydraulic machines, and his paddle-wheel concept belongs to that wider body of engineering work. The drawings do not establish that he built a full-scale working boat, but they clearly show the mechanical principle later used in paddle steamers.
A paddle wheel is different from a screw propeller. A paddle wheel works with broad blades or boards mounted around a rotating wheel, while a propeller uses helical blades beneath or behind the hull. Leonardo also investigated other naval ideas, so the paddle boat should not be confused with his proposed diving equipment.