Leonardo da Vinci developed a number of designs that were well before their time. His vision of vertical flight with his spiral helicopter, paddle wheel-powered vessels, and the early armored car may have been laughable in his day, but were the stepping stones for today's MV-22 Osprey, turbine-powered Ticonderoga-class cruisers, and M1 Abrams tank (and their analogs from other nations of course).
In the case of the paddleboat, Da Vinci envisioned a means of propulsion for ships and smaller craft that didn't rely on sails or oars, but rather a pair of paddle wheels, one on either side of the boat, which could provide sufficient power to travel up river or through strong winds and currents at sea. While the notion of paddlewheel propulsion did not originate with da Vinci, he was one of several designers that put forward paddle wheel concepts in the 15th Century. The design was man-powered at the time as practical steam power was still several centuries away.
In the case of the paddleboat, Da Vinci envisioned a means of propulsion for ships and smaller craft that didn't rely on sails or oars, but rather a pair of paddle wheels, one on either side of the boat, which could provide sufficient power to travel up river or through strong winds and currents at sea. While the notion of paddlewheel propulsion did not originate with da Vinci, he was one of several designers that put forward paddle wheel concepts in the 15th Century. The design was man-powered at the time as practical steam power was still several centuries away.