Post World War Submarines
Both the U.S. and Soviet navies benefited from German submarine technology after World War II. The German U-boats developed late in the war could travel underwater at high speeds and with extended range. This was due to the snorkel, streamlined hull designs, and larger electric batteries. Postwar diesel-electric submarines made the most of these innovations, and underwater maneuverability and speed increased. The beginning of the nuclear age in the 1950s, however, led both sides to embrace reactor power in submarines (and later in surface warships) to increase range and capability even more.
The first nuclear-powered submarine, the USS Nautilus, was launched in 1954 and commissioned in the following year. In a trial run conducted in 1955, the Nautilus sailed totally submerged from New London, Connecticut, to San Juan, Puerto Rico, a distance of 2170 km (1350 mi) in 84 hours. Its cruising speed submerged was more than 20 knots, and since the sub was nuclear-powered, it no longer needed to periodically surface for air or for refueling. Early in August 1958 the Nautilus made the first undersea transit of the North Pole, cruising under the polar ice pack from Point Barrow, Alaska, to a point between Spitsbergen, Norway, and Greenland.
Superpower submarine fleets grew steadily beginning in the 1950s during the Cold War arms buildup between the United States and the Union of Soviet Socialist Republics. Along with the number of submarines, the size of the subs themselves grew as well. After the fall of the USSR in 1991, the submarine fleets began thinning their ranks and reassessing their strategic and tactical roles. As the 20th century drew to a close, the United States still operated its ballistic missile and attack submarines, but had reduced the orders for newer and costly submarines such as the Seawolf attack subs. A post-Cold War doctrine of operating and fighting in shallow coastal waters emerged, and as a result, the U.S. Navy began revising its training and tactics for future conflicts. Threats of the future may include smaller enemy submarines lurking in shallow waters or in narrow waterways, rather than large subs traveling in deep ocean waters.
A submarine-launched ballistic missile (SLBM) thunders toward its practice target. Ballistic missile submarines are difficult to detect, and countries use their ability to launch nuclear-armed SLBMs as a deterrent to war.
Some U.S. Navy submarines have been used for scientific missions during the 1990s. In 1995, for example, the U.S. Navy announced the SCICEX (Scientific Ice Expeditions) project, which allowed civilian scientists to conduct missions below the polar ice caps aboard Sturgeon-class attack submarines. The agreement provided for one SCICEX mission a year for five years. Access to this underwater region had been restricted for years due to the harshness of the environment, the distance from support stations, and the danger of other military submarines lurking in the area. The submarines used for these scientific expeditions are specially suited for Arctic missions, and provided a rare opportunity for scientists to explore and map the Arctic Ocean floor, measure ice thickness, and collect water samples. Scientists hoped the missions set the stage for cooperation between the Navy and the scientific community on future expeditions.