watercraft propelled by a steam engine or a steam turbine.
Marquis Claude de Jouffroy d'Abbans is generally credited with the first experimentally successful application of steam power to navigation; in 1783 his Pyroscaphe ran against the current of the Saone River for 15 min, although the boiler could not generate enough steam for extended operations. In 1787 a steamboat built by James Rumsey of Maryland was demonstrated on the Potomac River; propelled by a stream of water forced out of the stern by steam pressure, the vessel attained a speed of 4 mi (6.4 km) per hr. Rumsey received a grant to navigate the waters of New York, Maryland, and Virginia. In 1790, John Fitch, who had previously built several successful steamboats, one of which operated in 1787, built a vessel capable of 8 mi (12.9 km) per hr which plied the Delaware River between Philadelphia and Burlington, N.J. Other early American steamboat inventors were Samuel Morey, Nathan Read, and John Stevens. In 1807, Robert Fulton launched the Clermont, 150 ft (46 m) long and powered by a Boulton and Watt steam engine. It ran from New York City to Albany (150 mi/241 km) in 32 hr and made the return trip in 30 hr. On the other side of the Atlantic, the Scotsman Henry Bell launched the Comet in 1812.
The first ocean crossing by a steam-propelled vessel was in 1819, when the Savannah voyaged from Savannah, Ga., to Liverpool in 29 days, 11 hr. It was a full-rigged sailing ship fitted with engines and side paddlewheels; during the crossing the engines were in use for about 85 hr. The first crossing under steam power alone was made in 1838, when two British steamship companies sent rival ships to New York within a few days of each other; the Great Western made the trip in 15 days, arriving a few hours after the Sirius, which had left England 4 days before her. The first seagoing vessel to be fitted with a screw propeller was the Archimedes (1840); the Great Britain (1845) was the first large iron steamship driven by a screw propeller to cross the Atlantic. By the late 1850s the screw propeller was conceded to be superior to paddlewheels, and the steamship began to supplant the sailing ship. In 1881 the Servia, a merchant steamer capable of crossing the Atlantic in 7 days, was the first vessel to be constructed of steel. Seven years later the Philadelphia, the first twin-screw steamship, was built at Glasgow.
Great liners propelled by engines of 28,000 or more horsepower began plying the Atlantic on regular schedules in the late 1800s. During the 1880s Sir Charles A. Parsons and C. G. P. de Laval developed the steam turbine, and the Turbinia, the first vessel to be driven by a turbine, was first seen in 1897. Within 10 years several turbine-driven liners were in the Atlantic service. Although multiple cylinders were added to reciprocating engines to take full advantage of the steam's expansion, within a decade the steam turbine virtually eliminated the older reciprocating steam engine on major vessels; the great transatlantic liners, such as the Queen Mary (launched 1934), the Queen Elizabeth (1938), and the United States (1951), were all turbine-powered. In 1955 the first nuclear-powered ship, in which the heat generated by nuclear fission is used to create the necessary steam, was launched. Nuclear-powered commercial vessels like the Savannah (launched in 1958 but since laid up) proved to be uneconomical because of the high cost of nuclear-power systems and environmental concerns; however, most large naval vessels are powered by nuclear steam plants.
Despite such innovations as turbo-electric drive, which converts steam energy into rotational power for turning the propeller shafts, commercial steamships have today given way to diesel-powered ships, which constitute 95% of new ship construction. Diesel engines provide a fuel efficiency of more than 50%, with a reliability at least equal to steam turbines. The Queen Elizabeth 2 (1969) was originally steam-powered, but it later was refitted with turbocharged diesel engines, which supply electric power to the propeller motors. The ocean liner has been replaced by the airplane as a means of transportation; its successor at sea is the cruise ship, which travels more slowly and functions as a vacation resort afloat rather than as scheduled transportation.