submarine

submarine
Name	Submarine
Caption	The Virginia-class attack submarine USS Virginia (SSN-774) underway.
Use	Naval warfare, reconnaissance, research
Built	17th century–present
In service	18th century–present

submarine. A submarine is a watercraft capable of independent operation underwater, distinct from a submersible, which has more limited underwater capability. Its primary military functions include attacking enemy surface ships, other submarines, and launching ballistic missiles or cruise missiles against land targets. Modern submarines are also used for specialized roles such as marine salvage, undersea cable repair, scientific research, and tourism, with designs ranging from small, autonomous vessels to the largest Ohio-class ballistic missile submarines.

History

The concept of an underwater boat has a long history, with early designs like those sketched by William Bourne and built by Cornelis Drebbel in the 17th century. The first militarily significant vessel was the Turtle, used by the Continental Army during the American Revolutionary War. The 19th century saw several innovations, including Robert Fulton's Nautilus and the Confederate States Navy's H. L. Hunley, which famously sank USS *Housatonic*. The advent of reliable combinations of steel hulls, electric batteries, and internal combustion engines in the late 19th and early 20th centuries, pioneered by designers like John Philip Holland and the Electric Boat Company, led to the first modern submarines adopted by the United States Navy and the Royal Navy. Their strategic impact was decisively demonstrated during World War I in campaigns like the U-boat campaign and the Battle of the Atlantic, a role further expanded in World War II by commanders such as Karl Dönitz of the Kriegsmarine. The post-war era was defined by the introduction of nuclear marine propulsion, pioneered by Hyman G. Rickover and first deployed on the USS *Nautilus*, which revolutionized underwater endurance and speed, a key factor in the Cold War rivalry between NATO and the Warsaw Pact.

Design

A modern naval submarine is a complex integration of systems designed to operate in a hostile environment. The pressure hull, typically constructed from high-strength HY-80 or HY-100 steel or titanium alloys as used on Soviet Alfa-class boats, is cylindrical to withstand immense hydrostatic pressure. It is surrounded by an outer hull which houses ballast tanks, sonar arrays like the AN/BQQ-5, and other systems. Maintaining a habitable atmosphere for the crew involves sophisticated oxygen generation, carbon dioxide scrubbers, and atmosphere monitoring equipment. Control is achieved through diving planes and rudders, with stability managed by a system of trim tanks. The design prioritizes stealth, employing anechoic tile coatings, raft mounting for machinery, and carefully shaped sail structures to minimize acoustic signature and radar cross-section.

Propulsion

Propulsion systems define a submarine's capabilities. Early boats used gasoline engines or diesel engines for surface running and recharging batteries that powered electric motors for submerged operation, a combination still used on modern diesel–electric submarines like the German Type 212. The revolutionary shift came with nuclear marine propulsion, where a nuclear reactor, such as a pressurized water reactor, generates steam to drive steam turbines connected to the propeller shaft, providing virtually unlimited submerged range and high speed, as seen on the American Los Angeles-class. Some modern non-nuclear designs, like the French Scorpène-class, utilize air-independent propulsion systems, such as Stirling engines or fuel cells, to significantly extend underwater endurance without surfacing.

Armament

The armament of a submarine is tailored to its mission. Attack submarines, like the Seawolf-class, are primarily equipped with torpedoes, such as the Mark 48, launched from torpedo tubes to engage ships and other submarines. They also carry submarine-launched cruise missiles like the Tomahawk for land attack. The primary weapon of the ballistic missile submarine (SSBN), a central component of nuclear deterrence strategies like those of the United Kingdom's Vanguard-class or Russia's Borei-class, is the submarine-launched ballistic missile, such as the Trident II. Many modern submarines also have the capability to deploy naval mines and can carry and launch unmanned underwater vehicles for reconnaissance or other missions.

Operations

Submarine operations are characterized by stealth, endurance, and independent action. Key missions include intelligence, surveillance, and reconnaissance, fleet in being deterrence, anti-submarine warfare, and anti-surface warfare. During the Cold War, United States Navy and Soviet Navy submarines engaged in close monitoring and trailing operations, chronicled in incidents like the *K-129* loss. Ballistic missile submarines execute deterrence patrols, remaining undetected for months to provide a guaranteed second-strike capability. Communication with national command authorities while submerged is maintained via very low frequency and extremely low frequency radio systems. Operations require highly trained crews, with training facilities like the Royal Navy Submarine School at HMNB Clyde preparing personnel for the unique challenges of underwater service.

Types and classes

Submarines are classified by their primary role and propulsion. The main military types are ballistic missile submarines (SSBN), attack submarines (SSN/SSK), and cruise missile submarines (SSGN). Prominent classes include the large Ohio-class SSBNs, the versatile Virginia-class SSNs, and the Russian Yasen-class multi-purpose boats. Diesel–electric submarines, such as the Japanese Sōryū-class or Swedish Gotland-class, are favored by many navies for coastal defense. Specialized types include midget submarines, used by forces like the British Special Boat Service, and deep-diving research vessels like *Alvin*, which explored the wreck of RMS *Titanic*. The future of submarine technology is being shaped by programs like the Royal Navy's Dreadnought-class and the development of increasingly autonomous systems.

Category:Submarines Category:Naval warfare Category:Nautical terminology