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 submarine work mainly in tropical and resort areas. In 1996 there were over 50 private submarines operating around the world. They carried approximatly 2 million passengers that year. Most of these submarines carried between 25 and 50 passengers and sometimes made 10 or more dives a day. These submarines borrow mainly from research sub designs with large windows for viewing and many have significant mechanical systems on the outside the the sub to free up 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.
Military submarines are cigar?-shaped and have a raised tower on top, on which are mounted radio antennas and a periscope?. Sonar? is a principle means of navigation. 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. A typical military submarine has a crew of over one hundred.
Submarines are useful to a military because they can approach their attach victim without necessarity being detected, then strike at close range. They come in two general types.
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 cell]?s.
Military submarines have a long history. The first was the Turtle, a hand-powered spherical contraption designed by American David Bushnell that accomodated a single man. In 1776, the Turtle attempted and failed to sink a British warship in New York harbour. Many more submarines were build subsequently, but they were not to become effective weapons until the 20th century.
The first military submarines to see effective use were the U-boats of Nazi Germany, introduced in World War I and again to devastating effect against the merchant ships of the United Kingdom during World War II. The U-boats ran on diesel? fuel and could only travel submerged for a short distance. Japan also used submarines during WWII.
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 United Kingdom employed nuclear submarines against Argentina in 1982 during the two nations' dispute over the Falkland Islands.
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, killing nine crewmen.
Articles on specific submarine vessels: USS Greeneville. Related topics: submarine sandwich, naval warfare tactics, USS Indianapolis.
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