A submarine is a specialized ship that travels under water, usually for military purposes. Most major navies of the world contain submarines. Submarines are also used for marine science and to work in water too deep for divers.
Scientific and commercial submarines
In common usage, submarine normally means military submarine; vessels used for research or commercial purposes are usually called submersibles. Non-military submarines are usually much smaller than military submarines. A type called a bathysphere is not self-propelled. A predecessor of the bathysphere was the diving bell, a chamber with an open bottom that is lowered into the water.
Tourist submarines work mainly in tropical resort areas. In 1996, there were over fifty private submarines operating around the world. They served approximately two million passengers that year. Most of these submarines carried between twenty-five and fifty passengers at a time and sometimes made ten or more dives a day. In design, these submarines borrow mainly from research subs, having large windows for passengers' viewing and often placing significant mechanical systems outside the the hull to conserve interior space. They are mainly battery-powered and very slow.
A fairly recent development, very small unmanned submarines called marine remotely operated vehicles are widely used today to work in water too deep or too dangerous for divers. For example, remotely operated vehicles repair offshore petroleum platforms and attach cables to sunken ships to hoist them. Such remotely operated vehicles are attached by a tether (a thick cable providing power and communications) to control center on a ship. Operators on the ship see video images sent back from the robot and may control its propellers and manipulator arm.
There are probably more military submarines in operation that any other type of submarine, though it is difficult to obtain exact figures because navies are secretive about their submarine fleets.
Submarines are useful to a military because they can approach their attack victim without necessarily being detected, then strike at close range. A great deal of attention in the design of a submarine is devoted to making its travel through the water silent to prevent its detection by enemy ships and submarines. Modern vessels have a cigar-shaped albacore shape. Their hulls are sleek and hydrodynamic. They are designed to operate almost always submerged, surfacing only rarely.
A raised tower on top of a submarine accommodates the length of the periscopes and electronics masts, which can include radio, radar, electronic warfare, and other systems. In the obsolete boat-shaped classes of submarines (see history, below), the control room, or conn, was located inside this tower, which was known as the conning tower. Since that time, however, conn has been located within the main body of the submarine, and the tower is more commonly called the sail today. In another interpretation, conning tower comes from the English verb to con, which means to navigate, indicating the presence of navigational systems in the conning tower. The conn should not be confused with the bridge, which is a small platform set into the top of the sail used for visual observation while running on the surface.
Sonar is a principle means of short-range navigation. The global positioning system is used for long-range navigation. The periscope is only used occasionally, since the range of visibility below the sea is short.
A typical military submarine has a crew of over one hundred. Their job is one of the most difficult assignments in the navy, for they must work in isolation for long periods, without much contact with their families, since submarines normally maintain radio silence to avoid detection. Operating a submarine is dangerous, even in peacetime; many submarines have been lost in accidents (see history, below).
Types of military submarines
Military submarines come in two general types: ballistic-missile submarines and attack submarines.
Ballistic missile submarines (or boomers, in American slang) are armed with nuclear weapons for attacking strategic targets such as cities or missile silos anywhere in the world. They are universally nuclear-powered, to provide the greatest stealthiness and endurance. They played an important part of Cold War mutual deterrence: since both the United States and the Soviet Union had the capability (or could contend to have) to heavily strike at the attacking nations should one attack the other, both nations were deterred.
Submarines armed with torpedoes, for attacking merchant ships or other warships, and sometimes cruise missiles for attacking land-based targets, are known as attack or hunter-killer submarines. They use a much wider variety of propulsion systems. The majority use the same diesel-electric combination developed early in the 20th century, many use nuclear power, and a growing number use other forms of air-independent propulsion such as fuel cells.
History of military submarines
Though the first submersible vehicles were tools for exploring under water, it did not take long for inventors to recognize their military potential. The first military submarine was the Turtle, a hand-powered spherical contraption designed by American David Bushnell that accommodated a single man. During the American Revolutionary War in 1776, the Turtle attempted and failed to sink a British warship in New York harbour.
During the American Civil War, the rebel South fielded a human-powered submarine. It was used for attacking the North's ships, which were blockading the South's seaports. The submarine had a long pole on the front, upon which was attached an explosive charge. The sub was to sneak up to an enemy vessel, attach the explosive, move away, and then detonate. It was extremely hazardous to operate, and had no air supply other than what was contained inside the main compartment. On at least one occasion, the sub sank, and the entire crew perished. It was not a major factor in the war.
In 1870, Jules Verne published the science fiction classic 20,000 Leagues under the Sea, which concerns the adventures of a maverick inventor in a submarine more advanced than any that existed at that time. The fictional story inspired Irish inventor John Holland to design and build several gasoline-powered submarines. Some of his vessels were purchased the United States, the United Kingdom, and Japan, and commissioned into their navies.
Many more submarines were built subsequently by various inventors, but they were not to become effective weapons until the 20th century. Both battery power and gasoline power were tried.
The first military submarines to see effective use were the U-boats of Germany, first introduced in World War I. The innovation that made the U-boats practical war machines was the their use of diesel fuel. More like submersible ships than the submarines of today, U-boats operated primarily on the surface, submerging occasionally to attack. Thus, they were roughly triangular in cross-section, with a distinct keel, to control rolling while surfaced. A group of U-boats called a pack (in German, Rudel) commonly traveled and fought together. (The term is often translated as wolf-pack, but the German word does not specify wolves.) The sinking of the ocean liner RMS Lusitania by a U-boat was a major factor in bringing the United States of America into the war.
Germany again put submarines to devastating effect against the merchant ships of the United Kingdom and the United States during World War II. Germany was thereby able to maintain a blockade against the United Kingdom that was only broken with the help of the United States. Japan also used submarines during WWII, sometimes on suicide missions.
In the 1950s, nuclear power partially replaced diesel fuel in those nations with access to nuclear technology. Equipment was also developed to extract oxygen from sea water. These two innovations gave submarines so equipped the ability to remain submerged for weeks or months. Non-nuclear nations continued to develop conventional forms of propulsion.
During the Cold War, the United States of America and the Soviet Union maintained large submarine fleets that engaged in cat-and-mouse games; Russia continues this tradition today. The Soviet Union suffered the loss of at least three submarines during this period: K-8 was lost in 1970, K-219 in 1986, and Komsomolets in 1989. (The loss by Russia, inheritor of the Soviet navy, of Kursk in 2000 cannot be credited to the Cold War). Many other Soviet subs, such as K-19 were badly damaged by fire or radiation leaks. The United States lost two nuclear submarines during this time: USS Thresher (SSN-593) and USS Scorpion (SSN-589).
Recently two tragedies involving submarines occurred. In 2000, the Russian submarine Kursk sank in the Arctic Ocean; an international rescue effort failed to save the crew. In 2001, the American submarine USS Greeneville accidentally struck and sank a Japanese ship, Ehime-Maru, killing nine Japanese crewmen.
Articles on specific submarine vessels and classes:
- Benjamin Franklin-class fleet ballistic missile submarines
- Ohio-class fleet ballistic missile submarines
- Sturgeon-class attack submarines
- Los Angeles-class attack submarines
- Seawolf-class attack submarines
- Virginia-class attack submarines
- Resolution class ballistic missile submarines
- On the Turtle: http://www.geocities.com/Athens/Acropolis/4870/DrGeorgePCPage9Turtle.html
- John Holland: http://www.clarelibrary.ie/eolas/coclare/people/holland.htm