page_title: United States floating battery Demologos
section_title: Design and impact
hierarchical_section_title: United States floating battery Demologos / Design and impact
caption_attribution_description: English: General arrangement of Demologos, first steam warship.
context_page_description: Demologos was the first warship to be propelled by a steam engine. She was a wooden floating battery built to defend New York Harbor from the Royal Navy during the War of 1812. The vessel was designed to a unique pattern by Robert Fulton, and was renamed Fulton after his death. Because of the prompt end of the war, Demologos never saw action, and no other ship like her was built.
context_section_description: Demologos had an entirely unique and innovative design. A catamaran, her paddlewheel was sandwiched between two hulls. Each hull was constructed 5 ft (1.5 m) thick for protection against gunfire. The steam engine, mounted below the waterline in one of the hulls, was capable of giving 5.5 knots (10.2 km/h) speed in favorable conditions. Although designed to carry 30 32-pounder guns, 24 port and starboard, 6 fore and aft, the Navy had trouble acquiring sufficient guns, and a varying number were mounted while in actual service. Demologos was also fitted for two 100-pounder Columbiads, one mounted fore and another aft, these weapons were never actually furnished to the vessel.
  Fulton's design solved several of the problems inherent in warships powered by paddlewheels which led to the adoption of the paddle-steamer as an effective warship in following decades. By placing the paddlewheel centrally, sandwiched between two hulls, Fulton protected it from gunfire; this design also allowed the ship to mount a full broadside of guns.
  The steam engine offered the prospect of tactical advantage against sail-powered warships. In a calm, sailing ships depended on the manpower of their crews to tow the ship from the boats, or to kedge with anchors. Demologos, with steam, might have found it easy to outmaneuver a ship-of-the-line in calm weather.
  The innovative construction and steam power also fundamentally limited the role Demologos could fill. With an unreliable engine and a hull unsuited to seaways, Demologos was unable to travel on the high seas. The United States Navy planned to build a number of similar steam batteries, but none of these plans got off the drawing board until the USS Fulton of 1837. A number of European navies also considered acquiring the Demologos, but these inquiries came to nought.
  The Demologos was ultimately a dead end in the introduction of steam power to the warship. Armed paddle steamers proliferated in the 1830s and 1840s as armed tugs and transports. During the Civil War, the United States Navy operated a number of iron clad steam-powered paddle-wheel gunboats as a part of the Mississippi River Squadron. Known as City-class ironclad gunboats as they were named after cities on the Mississippi River or its tributaries, these ships utilized a double-hulled configuration similar to Fulton's design, with the paddle wheel in the center. The wheel was protected by armored plate, allowing full broad-sides, as well as bow and stern shots. An example, USS Cairo, is on display at the Vicksburg National Military Park. Paddle-wheel propulsion, more usually side-paddle configurations, in military use continued until World War II with the training aircraft carriers USS Wolverine and USS Sable. These designs were typically limited to use in the brown-water navy or on large lakes.
  Steam-powered paddle wheel propulsion would ultimately be eclipsed by the introduction of the screw propeller in the 1840s, enabling steam-powered version of the ship of the line and the frigate before steam power was properly adapted for use in a blue water navy.
caption: Three-view of Demologos as originally portrayed to the US government. The resulting vessel differed greatly from this early proposal.
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