Attack Submarine

Attack Submarine, modern name for a naval vessel designed to operate principally underwater and to attack and destroy other submarines and surface ships using torpedoes and missiles. The ability of the attack submarine to operate independently—in total concealment and stealth—sets it apart from surface warships, which historically have operated in fleets for mutual protection. Early submarines were considered to be coastal patrol craft because of their limited range, cruising endurance, and weapon capacity. But as technology enabled them to range out into the deep ocean, submarines began to play key roles in attacking enemy warships and commercial supply ships.

Most attack submarines operate under either nuclear power (and are designated as SSN, for ship submersible nuclear) or diesel-electric power (and are designated as SS, for ship submersible). Nuclear subs can stay submerged for greater lengths of time than diesel-electric subs can, and nearly all of the U.S. Navy’s submarines are nuclear powered. Advances in nuclear technology enable modern nuclear attack submarines to be larger than earlier SSNs. They can also operate at deeper ocean depths, and carry a larger number of weapons than early nuclear subs. For instance, the United States Navy's modern USS Seawolf SSN displaces 8300 metric tons of water when submerged, compared with the 2860 metric tons of water displaced by the 1960s-era USS Skipjack SSN. The Seawolf also carries 50 torpedoes to the Skipjack’s 21.

Modern nuclear attack submarines can perform a variety of missions, including attacking submarines and surface ships; gathering secret information; attacking targets on land, using Tomahawk cruise missiles; using mini-submersibles to carry military personnel; and laying underwater mines. Since World War II (1939-1945), attack submarines have been built for specific tasks. The USS Sturgeon and other subs of its class were equipped with reinforced sail and hull plating, a taller sail structure, and special control planes to enable the submarines to operate below the Arctic ice cap. The Soviet-era Alpha class sub was a small attack submarine constructed with a titanium hull and a powerful nuclear reactor. This high speed submarine could reach speeds estimated at 77 km/h (48 mph), and operating depths estimated at 600 to 900 m (2000 to 3000 ft). The Soviets also built a variant of the attack submarine for cruise missile delivery (see Guided Missiles).

Modern diesel-electric submarines also take advantage of ongoing advances in underwater combat technology. The need to recharge their electrical batteries constrains the underwater range and endurance of modern diesel-electric submarines. However, these vessels operate more quietly while submerged than nuclear-powered submarines.

On a typical SSN mission, the submarine leaves its home port and submerges as soon it reaches the open ocean. Navigating by inertial guidance and occasional satellite guidance, the SSN reaches a specified target area. There, it searches for potential enemies using passive (undetectable) sonar, receiving antennas, or other special gear before heading on to the next target area. In wartime, SSNs also may intercept enemy subs or ships, lay mines, or bring military units ashore. See also Submarine; Nuclear Energy: Propulsion Reactors.