submarine

submarine, a vessel designed to operate below the surface of the sea. Its hull must be circular in transverse section to withstand the pressure of water to which it is subject when submerged. It must be fitted with ballast tanks to which water can be admitted to destroy its positive buoyancy when it wants to dive and from which the water can be expelled by compressed air when it wants to surface. To control the depth when the submarine is under way submerged, it needs horizontal rudders, and when dived it must have a propulsion system capable of operating without a supply of air. Until the advent of nuclear power, this could only be provided by electric motors powered by batteries. The endurance of the batteries was comparatively limited. To recharge them submarine had to use its diesel engines—on steam propulsion in the case of the K-class—which meant coming to the surface or employing its schnorkel.

Lengthways, the hull of the earlier submarines was cigar shaped, but it has now been found that optimum results are attained with a teardrop design of hull. Until the advent of nuclear-powered submarines, all others were really submersibles, that is they could not remain underwater permanently, but see also underwater vehicles.

Early Submarines.

Between 1578 and 1763 some seventeen designs of submarines have been recorded, and among the early pioneers of submarine design were the Americans David Bushnell and Robert Fulton. Further impetus was given to the design of submarines by the introduction of metal to shipbuilding, and in the latter half of the 19th century American and French engineers produced a number of models. During the American Civil War (1861–5) the ‘David’ submersibles were not a success, but the H. L. Hunley of the Confederate States Navy was the first submarine ever to sink a ship when she sank the USS Housatonic with a spar torpedo, though all her crew were killed in doing so.

At the turn of the century the invention of the diesel engine, coupled with that of the electric motor and the Whitehead torpedo, enabled real progress to be made with an effective design for a submarine. Credit for the design of the first really workable one belongs to the Irish-born American J. P. Holland (1840–1914), whose designs were accepted by the US Navy. The first five submarines built in Britain were also based on his design. They displaced 105 tons on the surface and had surface and submerged speeds of 8.5 and 7 knots respectively. Their surface endurance was 800 kilometres (500 mls.) at 7 knots using petrol-driven engines. In Germany it was decided to await the perfection of the much safer diesel engine before embarking on the construction of the first of a long line of U-boats (short for Unterseeboot) which were to play such an important part in the First (1914–18) and Second (1939–45) World Wars.

The Submarine in Two World Wars.

In 1914 there were some 400 submarines distributed among sixteen navies, of which Britain and France accounted for about half the total. Britain entered the war with 74 submarines and 31 building, Germany with 33 built and 28 building, but whereas most of the British boats were of a small, coastal type, the majority of those in the German Navy were open-sea types ranging between 550 and 850 tons displacement. During the war both sides built a number of submarines of varying types which included minelayers, a role for which the submarine is specially suitable. German construction was far and away the largest and ranged from the coastal UB types of 125–250 tons to the cruiser types of 1,700–3,200 tons capable of crossing the Atlantic.

Though there was little change in the basic design of submarines between the two world wars, they did play a much larger part in the war than in 1914–18, and the battle of the Atlantic, in which wolfpacks of U-boats attacked Allied convoys to sever the transatlantic supply route, was a crucial one. What were new were the midget-type submarines, developed initially by the Italians, who had pioneered them during the First World War, the Japanese, and later the British and Germans, to attack warships in defended harbours which conventional submarines had little chance of penetrating. Two of the most spectacular operations were the Japanese raid on Sydney Harbour in May 1942, and the crippling of the German battleship Tirpitz in September 1943 in Trondheim, Norway. Another important development in submarine warfare came in 1944 when Germany began to fit its U-boats with schnorkels which gave them a definite advantage, but by then the battle of the Atlantic had been won.

Nuclear-Powered Submarines.

In 1948 the US Atomic Energy Commission awarded a contract to the Westinghouse Electrical Company to develop a nuclear propulsion plant suitable for installation in a submarine, and on 14 June 1952 the keel of the first nuclear-powered submarine, USS Nautilus, was laid. Its completion meant that at long last the true submarine was a reality and in 1960 another nuclear-powered submarine, the USS Triton, made a circumnavigation of just over 40,000 kilometres (30,708 mls.) in 61 days without surfacing. The nuclear reactor fitted in vessels of this type is used to generate steam in much the same way as the ordinary boiler, but with certain modifications to prevent radiation injury to the crew. Since the reactor functions without the use of oxygen, the only factor limiting the time the submarine can remain submerged is the revitalization of the air to enable the crew to breathe. This is overcome by air-purifying machinery which enables the vessel to remain submerged almost indefinitely, and the modern nuclear-powered submarine, which is armed with nuclear warheads which can be fired from below the surface, can operate submerged at or near its maximum speed of about 30 knots for as long as is operationally necessary.

With the end of the Cold War the US Navy's force of nuclear-powered submarines is having to face change to meet the requirements of the navy's future strategy which was made public in 2002. For a start, four ‘Ohio’-class submarines have been armed with cruise missiles for attacking land targets and for handling Special Forces.

The problem of the only instance of a nuclear-powered submarine firing in anger was when HMS Conqueror torpedoed the Argentine cruiser General Belgrano during the Falklands conflict in 1982. She tracked her for two days before attacking, which would have been beyond the capability of any conventional submarine.

The problem of the disposal of Britain's redundant nuclear-powered submarines has yet to be solved. Currently (2004) there are eleven tied up in two British naval dockyards. The oldest, the Dreadnought, first brought into service in 1960, has been tied up since 1983.

See also warfare at sea.