President Abraham Lincoln was the only president to hold a patent.
He had an idea for a boat lift device that would help prevent boats from becoming stuck in sandbars. A set of bellows would be attached below the water line of the boat’s hull. When the boat reaches a shallow area, the bellows would fill with air and the boat would float higher. Lincoln created his own model for his patent application but his idea was never manufactured, probably because it device was cumbersome and the extra weight increased the chances of running aground.