Demologos had a unique and innovative design. A
catamaran, her
paddlewheel was sandwiched between two hulls. Each hull was constructed thick for protection against gunfire. The steam engine, mounted below the waterline in one of the hulls, was capable of giving 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 installed. 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 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, , 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 and . 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. ==References==