A steamboat is a boat that is propelled primarily by steam power, typically driving propellers or paddlewheels. Steamboats sometimes use the prefix designation SS, S.S. or S/S (for 'Screw Steamer') or PS (for 'Paddle Steamer'), however these designations are most often used for Steamships.
The term steamboat is used to refer to smaller, insular, steam-powered boats working on lakes and rivers, particularly riverboats. As using steam became more reliable, steam power became applied to larger, ocean-going vessels.
Early attempts at powering a boat by steam were made by the French inventor Denis Papin and the English inventor Thomas Newcomen. Papin invented the steam digester (a type of pressure cooker) and experimented with closed cylinders and pistons pushed in by atmospheric pressure, analogous to the pump built by Thomas Savery in England during the same period. Papin proposed applying this steam pump to the operation of a paddlewheel boat and tried to market his idea in Britain. He was unable to successfully convert the piston motion into rotary motion and the steam could not produce enough pressure. Newcomen's design did solve the first problem, but remained shackled to the inherent limitations of the engines of the time.
A steamboat was described and patented by English physician John Allen in 1729. In 1736, Jonathan Hulls was granted a patent in England for a Newcomen engine-powered steamboat (using a pulley instead of a beam, and a pawl and ratchet to obtain rotary motion), but it was the improvement in steam engines by James Watt that made the concept feasible. William Henry of Lancaster, Pennsylvania, having learned of Watt's engine on a visit to England, made his own engine. In 1763 he put it in a boat. The boat sank, and while Henry made an improved model, he did not appear to have much success, though he may have inspired others.