A steamship, often referred to as a steamer, is an ocean faring seaworthy vessel that is propelled by one or more steam engines that typically drive (turn) propellers or paddlewheels. The first steamships came into practical usage during the early 1800s; however, there were exceptions that came before. Steamships usually use the prefix designations of "PS" for paddle steamer or "SS" for screw steamer (using a propeller or screw). As paddle steamers became less common, "SS" is assumed by many to stand for "steam ship". Ships powered by internal combustion engines use a prefix such as "MV" for motor vessel, so it is not correct to use "SS" for most modern vessels.
The steamship was preceded by smaller vessels designed for insular transportation, called steamboats. Once the technology of steam was mastered at this level, steam engines were mounted on larger, and eventually, ocean-going vessels. Becoming reliable, and propelled by screw rather than paddlewheels, the technology changed the very design of ships for faster, more economic propulsion.
Paddlewheels as the main motive source became standard on these early vessels (see Paddle steamer). It was an effective means of propulsion under ideal conditions but otherwise had serious drawbacks. The paddle-wheel performed best when it operated at a certain depth, however when the depth of the ship changed from added weight it further submerged the paddle wheel causing a substantial decrease in performance.
Within a few decades of the development of the river and canal steamboat, the first steamships began to cross the Atlantic Ocean. The first sea-going steamboat was Richard Wright's first steamboat "Experiment", an ex-French lugger; she steamed from Leeds to Yarmouth in July 1813.
The first iron steamship to go to sea was the 116 ton Aaron Manby, built in 1821 by Aaron Manby at the Horseley Ironworks, and became the first iron built vessel ever to put to sea when she crossed the Channel in 1822 arriving in Paris on 22 June. She carried passengers and freight to Paris in 1822 at an average speed of 8 knots (9 mph, 14 km/h).