Submarine Technology Through the Years

	David Bushnell’s Turtle, the first American submarine. Built in 1775, its intended purpose was to break the British naval blockade of New York harbor during the American Revolution. With slight positive buoyancy, Turtle normally floated with approximately six inches of exposed surface. Turtle was powered by a hand-driven propeller. The operator would submerge under the target, and using a screw projecting from the top of Turtle, he would attach a clock-detonated explosive charge. This 1875 drawing by Lt. Francis Barber is the most familiar rendering of Turtle. However, it contains several errors, including internal ballast tanks and helical screw propellers. (Hi-Res)
	This more recent drawing of Turtle is based on Bushnell’s own written description, and is more accurate than the 1875 drawing by Lt. Barber. The most notable difference is the propeller; in Barber's drawing it is a helical screw, and here it is shown as a crude propeller. Also note that this drawing does not show ballast tanks. To submerge, the operator simply flooded water into the craft until it was negatively buoyant. This left the operator knee-deep in water. A hand pump was used to remove the water for returning to the surface. Drawing courtesy of John Batchelor. (Hi-Res)
	The Alligator was the first submarine purchased by the U.S. Navy. It contained two crude air purifiers, a chemical based system for producing oxygen and a bellows to force air through lime. (Hi-Res)
	The Confederate Submarine H.L. Hunley is credited with the first recorded successful underwater attack, against the USS Housatonic using a torpedo, which was projected from the submarine by a pole. Eight men turned the propeller using a handcrank. Maximum speed was 4 knots. Air was provided by two four-foot pipes, although the hull contained enough air for approximately ½ hour of submerged operations. (Hi-Res)
	The Intelligent Whale, a man-powered submarine purchased by the U.S. Navy in 1870, but never placed into service, featured air purifiers, pressurized air to empty ballast tanks and the ability to release a diver while submerged. The Intelligent Whale is credited with inspiring John Holland to develop his first submarine. (Hi-Res)
	The USS Holland had been purchased at the suggestion of the Assistant Secretary of the Navy, Theodore Roosevelt in 1898. He saw the potential use of this type of vessel in Havana Harbor during the Spanish-American War. John P. Holland’s company was purchased by his electric battery supplier in 1900. The resulting firm, Electric Boat Company of Groton, CT, grew to become one of Connecticut’s largest employers throughout the 20th Century. (Hi-Res)
	USS Seal, the first U.S. submarine built by Simon Lake. Mr. Lake was the only competitor of John Holland and is credited with the following design aspects of the modern submarine: escape trunk, conning tower, diving planes, control room, and the rotating, retractable periscope. (Hi-Res)
	Coastal and harbor defense was one of the earliest missions of the submarine force. Since early submarines could not transit over long distances they were transported by colliers. The U.S. Navy recognized the need to improve submarine design to allow for long range, high-speed operation while submerged. During the winter of 1909, the U.S. submarine C-1 conducted the first tests of the predecessor to today’s snorkel masts. Called ventilator tubes, this technological innovation provided surface air to the diesel engines while the submarine was at periscope depth. (Hi-Res)
	Simon Lake’s R-6 (S-83) submarine served as a test platfor m for the first U.S. experimental snorkel in 1945. (Hi-Res)
	L-10, one of the Electric Boat L class submarines. This class introduced the first strengthened internal bulkheads in submarines, which allowed the boats to dive to deeper depths. (Hi-Res)
	The L-boats, stationed in the Azores during World War One, introduced air purification to the submarine fleet. Stale air was blown over chemicals, and compressed oxygen was released into the submarine to supplement the interior atmosphere. (Hi-Res)
	World War I illustrated a need to shift the priorities in submarine construction and operation. In order to be effective combatants, submarines required improved stealth capabilities such as rapid submergence (i.e., crash dives) and long submerged endurance at low speeds following a torpedo attack. Existing submarines were all considered too small to incorporate these capabilities. However, such designs like the H-boat pictured here, H-2 (circa 1920), were the only ones that could be built quickly. As a result, these submarines were overloaded with the addition of key elements required for wartime sailing-chariot bridge, torpedo room ventilation, oscillator, and gyrocompass. (Hi-Res)
	Following World War I, a long range, high endurance submarine became a critical need. The first U.S. unit was authorized for construction in 1925. V-4, later renamed Argonaut, was originally intended for a minelaying mission. This submarine had twice the battery volume of earlier designs and included the first 240v electrical system, allowing for smaller onboard electric motors. Argonaut served as a predecessor to the submarine designs utilized during World War II. (Hi-Res)