Submarine

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For other uses, see Submarine (disambiguation).

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A submarine is a specialized watercraft that can operate underwater. Military submarines are used by all major navies today, especially US and Russian, and were first actively used in the First World War. Civilian submarines and submersibles are used for marine and freshwater science and for work at depths too great for human divers.

Nuclear powered submarines and other large submarines are classed as ships, but are customarily referred to by their crews as "boats". The term U-Boat is sometimes used for German submarines in English. This comes from the German word for submarine, 'U-Boot', itself an abbreviation for Unterseeboot ('undersea boat').

Submarines encompass one of the largest ranges in capabilities of any vessel. They range from small two-man vessels that can examine the sea floor for a few hours to the Russian Typhoon class, which can remain submerged for half a year and carry enough nuclear missiles to destroy hundreds of cities. There is a wide variety of specialized submarines: rescue submarines like the DSRV or Priz, or tiny one-person human powered subs intended for competitions between universities. An older device for use in underwater exploration, salvage, construction and rescue is the diving bell.

The word submarine was originally an adjective meaning "under the sea". Some firms who make diving gear but not parts for submarines, called their work "submarine engineering". "Submarine" as a noun meaning a submersible craft originated as short for "submarine boat" and older books such as Twenty Thousand Leagues Under the Sea always use this term.


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Civilian submarines and submersibles

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Civilian submarines are usually much smaller than military submarines. Tourist submarines work mainly in tropical resort areas or other areas with clear water and good visibility. By 1996 there were over fifty private submarines operating around the world, serving approximately two million passengers a year. Most of them carried between twenty-five and fifty passengers at a time and sometimes made ten or more dives per day. In design, these submarines borrow mainly from research subs, having large portholes for passengers' viewing and often placing significant mechanical systems outside the hull to conserve interior space. Nonetheless, even aboard tourist submarines the seating can be rather cramped. They are mainly battery-powered and very slow.

As of January 2005, the largest tourist submarine in use was the Atlantis XIV based out of Waikiki beach. The largest Atlantis-class submarine of its fleet, launched in 1994, can carry 64 passengers and 3 crew (two guides and a pilot) to 150 feet deep (this depth set by the state) off the shores of the island of O'ahu in Hawai'i. There, tourists can view a great number of ocean specimens living around artificial reefs built by the Hawaiian university out of old ships, constructions of metal flotsam, and even a sunken plane, all designed to replace the reefs damaged or destroyed by human habitation of the island.

In common usage, "submarine" means a ship which operates above and below the surface, untethered. Underwater vessels with limited mobility, intended to remain in one place during most of their use, such as those used for rescue, research or salvage purposes are usually called "submersibles". Submersibles are typically transported to their area of operation by surface ships or large submarines and have a very short range. Many submersibles operate on a "tether" or "umbilical", remaining connected to a tender (a submarine, surface vessel or platform).

A bathysphere or bathyscaphe is a type of submersible which lacks self-propulsion. A predecessor of the bathysphere, the diving bell, consisted of a chamber with an open bottom, lowered into the water.

A fairly recent development, very small unmanned submersibles called "marine remotely operated vehicles" or MROVs are widely used today to work in water too deep or too dangerous for divers. For example, remotely operated vehicles (ROVs) 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. The wreck of the Titanic was explored by such a vehicle, as well as by a manned vessel.

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Military submarines

There are more military submarines in operation than civilian ones. Submarines are useful militarily because they are difficult to locate and, when deep below the surface, difficult to destroy. A great deal of attention in the design of a submarine is devoted to making its travel through the water as silent as possible in order to prevent its detection (sound travels underwater much more easily than does light, meaning that a submarine's sound is the distinctive feature most likely to allow its detection). If a submarine remains undetected, it is able to strike at close range.

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Submersion and navigation

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All surface ships, as well as surfaced submarines, are in positively buoyant condition, weighing less than the water they displace. To submerge hydrostatically, a ship must gain negative buoyancy, either increasing its weight or decreasing displacement. To control their weight, submarines are equipped with ballast tanks, which can be filled with either outside water or pressurized air.

For general submersion or surfacing, submarines use the forward and aft tanks, called Main Ballast Tanks or MBTs, which are opened and completely filled with water to submerge, or filled by pressurized air to surface. In submerged condition MBTs generally always stay flooded, which simplifies their design, so on many submarines these tanks are simply a section of interhull space. For more precise and quick control of depth, submarines use smaller Depth Control Tanks or DCTs, also called hard tanks due to their ability to withstand higher pressure. The amount of water in depth control tanks can be controlled either to reflect changes in outside conditions or change submersion depth. Depth control tanks can be located either near the submarine's centre of gravity, or separated along the submarine body to prevent affecting trim.

When submerged, the water pressure on submarine's hull can reach 3 MPa for steel submarines and up to 10 MPa for titanium submarines like Komsomolets, while the pressure inside stays the same. This difference results in hull compression, which decreases displacement. Water density also increases, as the salinity and pressure are higher, but this does not compensate for hull compression, so buoyancy falls with depth. A submerged submarine is in an unstable equilibrium, having a tendency to either fall down to the ocean floor or float up to the surface. Keeping a constant depth requires continual operation of the depth control tanks.

Submarines in a neutral buoyancy condition, are not intrinsically stable in trim. To sustain desired trim, submarines use specialized forward and aft trim tanks. Pumps can move water between these tanks, changing the weight distribution and therefore creating a momentum to turn the sub upwards or downwards. A similar system is sometimes used to maintain stability.

The hydrostatic effect of variable ballast tanks is not the only way to control the submarine underwater. Hydrodynamic maneuvering is done by several surfaces, which can be turned to create corresponding hydrodynamic forces when a submarine moves at sufficient speed. The stern planes, located behind the propeller and normally oriented horizontally, serve the same purpose as the trim tanks, controlling the trim, and are commonly used, while other control surfaces may not be present on many submarines. The fairwater planes on the sail and bow planes on the main body, both also horizontal, are located closer to the centre of gravity, and are used to control depth with less effect on the trim.

When a submarine performs an emergency surfacing, all depth and trim methods are used simultaneously, together with propelling the boat upwards. Such surfacing is very quick, so the sub may even partially jump out of the water, but it inflicts serious damage on some submarine systems, primarily pipes.

Modern submarines use an inertial guidance system for navigation while submerged, but drift error unavoidably builds up over time. To counter this, the Global Positioning System will occasionally be used to obtain an accurate position. The periscope - a retractable tube with prisms allowing a view to the surface - is only used occasionally in modern submarines, since the range of visibility is short. The Virginia-class submarines have "photonics masts" rather than hull-penetrating optical tube periscopes. These masts must still be hoisted above the surface, and employ electronic sensors for visible light, infra-red, laser range-finding, and electromagnetic surveillance.

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Submarine hull

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Modern submarines are usually cigar-shaped. This design, already visible on very early submarines (see below) is called a "teardrop hull", and was patterned after the bodies of whales. It significantly reduces the hydrodynamic drag on the sub when submerged, but decreases the sea-keeping capabilities and increases the drag while surfaced. Since the limitations of the propulsion systems of early military submarines forced them to operate on the surface most of the time, their hull designs were a compromise. Because of the slow submerged speeds of those subs, usually well below 10 kt, the increased drag for underwater travel was considered acceptable. Only late in World War II, when technology allowed faster and longer submerged operations and increased surveillance by enemy aircraft forced submarines to stay submerged, did hull designs become teardrop shaped again, to reduce drag and noise. On modern military submarines the outer hull is covered with a thick layer of special sound-absorbing rubber, or anechoic plating, to make the submarine quieter.

A raised tower on top of a submarine accommodates the length of the periscope and electronics masts, which can include radio, radar, electronic warfare, and other systems. In many early classes of submarines (see history), the Control Room, or "Conn", was located inside this tower, which was known as the "conning tower". Since that time, however, the Conn has been located within the hull of the submarine, and the tower is more commonly called the "sail" today. The Conn should not be confused with the "bridge", which is a small, open platform set into the top of the sail used for visual observation while operating on the surface. There may also be an additional closed platform below this with windows and wipers for bad weather.

All small modern submarines and submersibles, as well as the oldest ones, have a single hull. However, for large submarines, the approaches have separated. All Soviet heavy submarines are built with a double hull structure, but American submarines usually are single-hulled. They still have light hull sections in bow and stern, which house main ballast tanks and provide hydrodynamically optimized shape, but the main, usually cylindrical, hull section has only a single plating layer. There are also examples of more than two hulls in a submarine, like the Typhoon class, which has two main pressure hulls and three smaller ones for control room, torpedoes and steering gear, while the missile launch system is located between the main hulls.

A submarine's double-hull is different from a ship's double hull. The external hull, which actually forms the shape of submarine, is called the outer hull or light hull, as it does not have to hold any pressure difference. The light hull can be used to mount equipment, while attaching it directly to the pressure hull could increase local stress on the pressure hull. A double-hull approach also saves space inside the pressure hull, as the ring stiffeners and longitudinals are located between hulls. These measures allow the size of the pressure hull, which is much heavier than the light hull, to be minimised. Also, in case the submarine is damaged, the light hull takes some of the damage, without compromising the boat's integrity, as long as the strong hull is intact. The major downside of double-hull structure is the significantly greater amount of manual welding required to construct it. The Soviet Union had implemented the welding techology earlier and had enough cheap qualified workforce available, but the high cost of manual labor in the United States made less expensive single-hull approach more preferrable. Another reason for double-hull construction in the Soviet Union was operation under the Arctic Ocean, where submarines had to break thick ice, which could damage the hull.

Inside the outer hull there is a strong hull, or pressure hull, which withstands sea pressure and has normal atmospheric pressure inside. The pressure hull is generally constructed of thick high-strength steel with a complex structure and high strength reserve, and is separated with watertight bulkheads into several compartments. The pressure and light hulls form a three-dimensional structure with increased strength. The inter-hull space is used for some of the equipment not requiring constant pressure to operate. The list significantly differs between submarines, and generally includes different tanks.

The dive depth cannot be increased easily. Simply making the hull thicker increases the weight and requires reduction of the weight of onboard equipment, ultimately resulting in a bathyscaphe. This is affordable for civilian research submersibles, but not military submarines, so their dive depth was always bound by current technology.

WW1 submarines had their hulls built of carbon steel, and could not submerge below 100 meters. During World War Two, high-strength alloyed steel was introduced, allowing for depths up to 200 meters. High-strength alloyed steel is still the main material for submarines today, with 250-350 meters depth limit, which cannot be exceeded on a military submarine without sacrificing other characteristics. To exceed that limit, a few submarines were built with titanium hulls. Titanium is stronger and lighter than steel, and is non-magnetic. Titanium submarines were especially favored by the Soviets, who developed specialized high-strength alloys, built an industry for producing titanium with affordable costs and have several types of titanium submarines. Titanium alloys allow a major increase in depth, but other systems need to be redesigned as well, so test depth was limited to 1000 meters for K-278 Komsomolets, the deepest-diving military submarine. An Alfa class submarine may have successfully operated at 1300 meters <ref>Federation of American Scientists</ref>, though continuous operation at such depths would be an excessive stress for many submarine systems. Despite its benefits, high costs of titanium construction led to abandonment of titanium submarines idea as the Cold War ended.

The task of building a pressure hull is very difficult, as it must withstand a force of several million tons. When the hull is perfectly round in cross-section, the pressure is evenly distributed, and causes only hull compression. If the shape is not perfect, the hull is bent, with several points heavily strained. Inevitable minor deviations are resisted by the stiffener rings, but even a one inch deviation from roundness results in over 30 percent decrease of maximal hydrostatic load <ref>US Naval Academy</ref>. The hull must therefore be constructed with very high precision. All hull parts must be welded without defects, and all joints are checked several times using different methods. This contributes to very high cost of modern submarines (for instance, a Virginia class attack submarine costs 2.6 billion dollars, over $200,000 per ton of displacement).

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Propulsion

Until the advent of nuclear marine propulsion, most 20th century submarines used batteries for running underwater and gasoline (petrol) or diesel engines on the surface and to recharge the batteries. Early boats used gasoline but this quickly gave way to paraffin, then diesel, because of reduced flammability. Diesel-electric became the standard means of propulsion. Initially the diesel or gasoline engine and the electric motor were on the same shaft which also drove a propeller with clutches between each of them. This allowed the engine to drive the electric motor as a generator to recharge the batteries and also propel the submarine if required. The clutch between the motor and the engine would be disengaged when the boat dived so that the motor could be used to turn the propeller. The motor could have more than one armature on the shaft — these would be electrically coupled in series for slow speed and parallel for high speed (known as "group down" and "group up" respectively).

In the 1930s the principle was modified for some submarine designs, particularly those of the U.S. Navy and the British U-class. The engine was no longer attached to the motor/propeller drive shaft but drove a separate generator which would drive the motors on the surface and/or recharge the batteries. This diesel-electric propulsion allowed much more flexibility, for example the submarine could travel slowly whilst the engines were running at full power to recharge the batteries as quickly as possible, reducing time on the surface, or use its snorkel. Also it was now possible to insulate the noisy diesel engines from the pressure hull making the submarine quieter.

There were other power sources attempted—oil-fired steam turbines powered the British "K" class submarines built during the First World War and in the following years, but these were not very successful. This was selected to give them the necessary surface speed to keep up with the British battle fleet.

Steam power was resurrected in the 1950s with the advent of the nuclear-powered steam turbine driving a generator which is now used in all large submarines. By removing the requirement for atmospheric oxygen these submarines can stay submerged indefinitely so long as food supplies remain (air is recycled and fresh water distilled from seawater). These vessels always have a small battery and diesel engine/generator installation for emergency use if the reactors have to be shut down.

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Anaerobic propulsion was employed by the first mechanically driven submarine Ictineo II in 1864. Ictineo's engine used a chemical mix containing a peroxide compound, that generated heat for steam propulsion while at the same time solved the problem of oxygen renovation in an hermetic container for breathing purposes. The system was not employed again until 1940 when the German Navy tested a system employing the same principles, the Walter turbine, on the experimental V-80 submarine and later on the naval U-791 submarine. At the end of the Second World War the British and Russians experimented with hydrogen peroxide/kerosene (paraffin) engines which could be used both above and below the surface. The results were not encouraging enough for this technique to be adopted at the time, and although the Russians deployed a class of submarines with this engine type code named Quebec by NATO, they were considered a failure. Today several navies, notably Sweden, now use air-independent propulsion boats which substitute liquid oxygen for hydrogen peroxide.

The German Type 212 submarine uses nine 34-kilowatt hydrogen fuel cells as air-independent propulsion, which makes it first series production submarine using fuel cells.

Most small modern commercial submarines which are not expected to operate independently use batteries which can be recharged by a mother-ship after every dive.

Towards the end of the 20th century, some submarines began to be fitted with pump-jet propulsors instead of propellers. Although these are heavier, more expensive, and often less efficient than a propeller, they are significantly quieter, giving an important tactical advantage.

A possible propulsion system for submarines is the magnetohydrodynamic drive, or "caterpillar drive", which has no moving parts. It was popularized in the movie version of The Hunt for Red October, written by Tom Clancy, which portrayed it as a virtually silent system. (In the book, a form of propulsor was used rather than an MHD.) Although some experimental surface ships have been built with this propulsion system, speeds have not been as high as those hoped. In addition, the noise created by bubbles, and the higher power settings a submarine's reactor would need, mean that it is unlikely to be considered for any military purpose.

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Life support

With nuclear power, submarines can remain submerged for months at a time. Diesel submarines must periodically resurface or snorkel to recharge their batteries. Most modern military submarines are able to generate oxygen for their crew by electrolysis of water. Atmosphere control equipment includes a CO2 scrubber, which uses a catalyst to remove the gas from air and diffuse it into waste pumped overboard. A machine that uses a catalyst to convert carbon monoxide into carbon dioxide (removed by the CO2 scrubber) and bonds hydrogen produced from the ship's storage battery with oxygen in the atmosphere to produce water, also found its use. An atmosphere monitoring system samples the air from different areas of the ship for nitrogen, oxygen, hydrogen, R12 and R114 refrigerant, carbon dioxide, carbon monoxide, and others. Poisonous gases are removed, and oxygen is replenished by use of an oxygen bank located in a main ballast tank. Some heavier submarines have two oxygen bleed stations (forward and aft). The oxygen in the air is sometimes kept a few percent less than atmospheric concentration to reduce fire danger.

Fresh water is produced by an evaporator, and is used for showers, sinks, cooking and cleaning. Sea water is used to flush toilets, and the resulting "black water" is stored in a sanitary tank until it is blown overboard using pressurised air. This system is difficult to operate, and the German Type VIIC boat U-1206 was lost with casualties because of a mistake with the toilet. Water from showers and sinks is stored separately in "gray water" tanks, which are pumped overboard using the drain pump.

Trash on modern large submarines is usually disposed of using a sort of torpedo tube called a Trash Disposal Unit (TDU), where it is compacted into a galvanised steel can. At the bottom of the TDU is a large ball valve. An ice plug is set on top of the ball valve to protect it, the cans on top of the ice plug. The top breech door is shut, and the TDU is flooded and equalised with sea pressure, the ball valve is opened and the cans fall out to the ocean floor assisted by scrap iron weights inside the cans.

A typical nuclear submarine has a crew of over 120; non-nuclear boats typically have less than half as many. The conditions on a submarine can be difficult because crew members must work in isolation for long periods of time, without contact with their families. Submarines normally maintain radio silence to avoid detection. Operating a submarine is dangerous, even in peacetime, and many submarines have been lost in accidents.

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Types of military submarines

Military submarines are generally divided into attack submarines, designed to operate against enemy ships, including other submarines, in a hunter-killer role, or strategic ballistic-missile submarines, designed to launch attacks on land-based targets from a position of stealth, also known as "boomers" in the United States Navy or "bombers" in the Royal Navy. The division between these classes refers to role rather than construction, and submarines designed to destroy enemy fleets from long distances with multiple nuclear missiles are similar to SSBN in size, armament and other facilities.

Every known strategic, ballistic-missile carrying submarine (SSBN) operated today is nuclear powered. In regard to tactical nuclear weapons, it is widely rumored that Israel tested nuclear-capable cruise missiles from two German-built Dolphin-class diesel submarines in May 2000 which thus may have reached operational capability today.

U.S. SSNs no longer carry nuclear-tipped Tomahawk cruise missiles as a result of nuclear arms control agreements. Some older, Trident class SSBN submarines are however scheduled to be converted to carry multiple conventional-warhead, "guided" Tomahawk missiles and thus become redesignated as an SSGN.

Attack submarines may be divided in two general types: Nuclear (what the U.S. calls a fast-attack submarine; SSN) or diesel-electric (SS). Nuclear powered submarines are faster and larger, and have more firepower and longer mission endurance than diesel-electrics. Depending on the submarine's overall mission, the diesel-electric submarine is sometimes more suited for shallow water or littoral operations. To close the gap between the two very different designs several navies have started the development of air-independent propulsion boats which are used like diesel-electric submarines with an enlarged diving period.

The tactics which called for groups of specialized submarines, such as the squadrons which contained each of the Japanese Types A, B, and C, of which the first two carried scout seaplanes, are now obsolete. Other obsolete types include radar-picket submarines, such as USS Triton; specialized mine-layers; and those which carried attack seaplanes, such as the Japanese I-400-class.

Other categories include midget submarines, used for sabotage and espionage. Five of this type were used by Japan in the attack on Pearl Harbor. Another unusual category was the World War II German Type XIV milchkuh submarines: submersible supply vessels.


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Ballistic Missile Submarines

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Ballistic missile submarines (SSBNs or boomers in American slang) carry submarine-launched ballistic missiles (SLBM) with nuclear warheads, for attacking strategic targets such as cities or missile silos anywhere in the world. They are currently universally nuclear-powered, to provide the greatest stealth and endurance. (The first Soviet ballistic missile submarines were diesel-powered.) They played an important part in Cold War mutual deterrence, as both the United States and the Soviet Union had the credible ability to conduct a retaliatory strike against the other nation in the event of a first strike. This comprised an important part of the strategy of Mutual Assured Destruction.

Image:USS Michigan (SSBN-727).jpg The U.S. has 18 Ohio class submarines, of which 14 are Trident II SSBNs, each carrying 24 SLBMs. The first four Ohio class vessels were equipped with Trident I, and are now being converted to carry Tomahawk guided missiles.

For Russia, see List of NATO reporting names for ballistic missile submarines.

Image:HMS Renown (Resolution-class submarine) .jpg The Royal Navy possess a single class of four ballistic missile submarines, the Vanguard class. The Royal Navy's previous ballistic missile submarine class was the Resolution class which also consisted of four boats. The Resolutions, named after battleships to convey the fact they were the new capital ships, were decommissioned when the Vanguards entered service in the 1990s.

France operates a force de frappe including a nuclear ballistic submarine fleet made up of one SSBN Redoutable class and three SSBNs of the Triomphant class. One additional SSBN of the Triomphant class is under construction.

The People's Republic of China's People's Liberation Army Navy's SLBM inventory is relatively new. China launched its first nuclear armed submarine in April 1981. The PLAN currently has 1 Xia class ("Type 92") at roughly 8,000 tons displacement. The Type 92 is equipped with 12 SLBM launching tubes. China's SLBM program is built around its JL-1 inventory. The Chinese Navy is estimated to have 24 JL-1s. The JL-1 is basically a modified DF-21.

The PLAN plans to replace its JL-1 with an unspecified number of the longer ranged, more modern JL-2s. Deployment on the JL-2 reportedly began in late 2003.

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Attack boats

Submarines designed for the purpose of attacking merchant ships or other warships are known as "fast attacks", "hunter-killers", "fast boats", or "fleet submarines" (which terms are not synonyms; each is a different design for a different mission). They typically carry torpedoes for attacking naval vessels, and today carry cruise missiles for attacking either land-based targets or shipping. On American submarines, cruise missiles can be fired horizontally through a submarine's torpedo tubes, or, on newer vessels, via specially designed vertical launch tubes. The former has an effect of reducing the available torpedoes a submarine can carry, while the latter requires it to be reloaded by a submarine tender or by returning to port. The Soviet Navy also developed several types of missile attack submarines (SSGNs), which carried a heavy load of anti-surface missiles, as their primary targets were U.S. aircraft carriers.

Attack submarines can use a wide variety of propulsion systems. The majority of non-nuclear submarines use the same diesel-electric combination developed early in the 20th century, many use nuclear power, and a small but growing number use some other form of air-independent propulsion such as fuel cells or Stirling engines. All of the attack submarines of the United States use nuclear power.

Until the 1980s, Soviet attack submarines were designed around the concept of Anti-Surface Warfare so they tended to be fast and noisy. Due primarily to a U.S. sailor and communications technician who spied for the Soviet Union, John Anthony Walker, the Soviet Union learned NATO naval forces could track them quite easily and over time redesigned their submarines to operate much more quietly, and redeployed them into defensive bastions. The Victor III was the first class of Soviet submarines to be built with this new capability; armed with torpedoes, SUBROCs, and cruise missiles, they posed a more significant threat to NATO sea power. Today Russian Akula (Shark), Sierra, and Graney class submarines continue in design innovation and are respected as some of the finest submarines in the world.

Image:HMS Tireless S-88.jpg Just before the 1990s, the Royal Navy consisted of diesel and nuclear powered submarines but, due to the end of the Cold War, financial cuts saw the RN submarine fleet became all-nuclear, presently consisting of the Swiftsure and Trafalgar class submarines, the latter named after the Battle of Trafalgar. The boats are armed with torpedoes, Harpoon anti-ship missiles and many are now armed with the Tomahawk cruise missile, which is fired from their torpedo tubes. The RN intends to have all of its attack submarines armed with the Tomahawk by 2008. During the Kosovo War, HMS Splendid became the first RN submarine to fire a Tomahawk in anger. The expected replacement of those classes is the Astute-class submarine, but delays have seen the expected launch of the first A class, HMS Astute, moved to 2009.

The role of all these attack boats has changed considerably since the end of the Cold War. U.S. fast boats no longer prowl the deep oceans in the hunt for the elusive Soviet, instead they provide cruise missile support, early warning and intelligence gathering, harbor mine clearing, Special Operation Warfare team delivery, and others. The Virginia class was specifically designed with this multiple-mission capability in mind.

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History of submarines

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Early history of submarines and the first submersibles

A far ancestor for a submarine is probably a 17th century Ukrainian Cossack riverboat called chaika (gull) that was used underwater for reconnaissance and infiltration missions. Chaika could be easily capsized and submerged so that the crew was able to breathe underneath like in a modern diving bell and propel the vessel by walking on the bottom of river. Special plummets for submerging and pipes for additional breathing were used.

The first submersible with reliable information on its construction was built in 1620 by Cornelius Jacobszoon Drebbel, a Dutchman in the service of James I. It was propelled by means of oars. The precise nature of the submarine type is a matter of some controversy; some claim that it was merely a bell towed by a boat. Two improved types were tested in the Thames between 1620 and 1624.

Though the first submersible vehicles were tools for exploring under water, it did not take long for inventors to recognize their military potential. The strategic advantages of submarines were set out by Bishop John Wilkins of Chester in Mathematicall Magick in 1648.

  1. Tis private: a man may thus go to any coast in the world invisibly, without discovery or prevented in his journey.
  2. Tis safe, from the uncertainty of Tides, and the violence of Tempests, which do never move the sea above five or six paces deep. From Pirates and Robbers which do so infest other voyages; from ice and great frost, which do so much endanger the passages towards the Poles.
  3. It may be of great advantages against a Navy of enemies, who by this may be undermined in the water and blown up.
  4. It may be of special use for the relief of any place besieged by water, to convey unto them invisible supplies; and so likewise for the surprisal of any place that is accessible by water.
  5. It may be of unspeakable benefit for submarine experiments.
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The first military submarines

Image:Bushnell-turtle-big.jpg The first military submarine was Turtle, a hand-powered egg-shaped device designed by the American David Bushnell, to accommodate a single man. It was the first verified submarine capable of independent underwater operation and movement, and the first to use screws for propulsion. During the American Revolutionary War, Turtle (operated by Sgt. Ezra Lee, Continental Army) tried and failed to sink a British warship, HMS Eagle (flagship of the blockaders) in New York harbor on September 7, 1776.

Image:FultonNautilus.jpg In 1800, France built a human-powered submarine designed by Robert Fulton, the Nautilus. It proved capable of using mines to destroy two warships during demonstrations. The French eventually gave up with the experiment in 1804, as did the British when they later tried the submarine.

During the War of 1812, in 1814, Silas Halsey lost his life while using a submarine in unsuccessful attack on a British warship stationed in New London harbor.

In 1851, a Bavarian artillery corporal, Wilhelm Bauer, took a submarine designed by him called the Brandtaucher (fire-diver) to sea in Kiel Harbour. This submarine was built by August Howaldt and powered by a treadwheel. It sank but the crew of 3 managed to escape. The submarine was raised in 1887 and is on display in a museum in Dresden.

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Submarines in the American Civil War

Image:USS Alligator 0844401.jpg During the American Civil War, the Union was the first to field a submarine. The French-designed Alligator was the first U.S. Navy sub and the first to feature compressed air (for air supply) and an air filtration system. She was the first submarine to carry a diver lock which allowed a diver to plant electrically-detonated mines on enemy ships. Initially hand-powered by oars, she was converted after 6 months to a screw propeller powered by a hand crank. With a crew of 20, she was larger than Confederate submarines. Alligator was 47 feet (14.3 meters) long and about 4 feet (1.2 meters) in diameter. She was lost in a storm off Cape Hatteras on April 1, 1863 while uncrewed and under tow to her first combat deployment at Charleston.

The Confederate States of America fielded several human-powered submarines including CSS H. L. Hunley (named for one of her financiers, Horace Lawson Hunley) . The first Confederate submarine was the 30-foot long Pioneer which sank a target schooner using a towed mine during tests on Lake Pontchartrain but she was not used in combat. She was scuttled after New Orleans was captured and in 1868 was sold for scrap.

CSS Hunley was intended for attacking the North's ships, which were blockading the South's seaports. The submarine had a long pole with an explosive charge in the bow, called a spar torpedo. The sub had to approach an enemy vessel, attach the explosive, move away, and then detonate it. It was extremely hazardous to operate, and had no air supply other than what was contained inside the main compartment. On two occasions, the sub sank; on the first occasion half the crew died and on the second, the entire eight-man crew (including Hunley himself) drowned. On February 18, 1864 Hunley sank USS Housatonic off the Charleston Harbor, the first time a submarine successfully sank another ship, though she sank in the same engagement shortly after signaling her success. Another Confederate submarine was lost on her maiden voyage in Lake Pontchartrain; she was found washed ashore in the 1870s and is now on display at the Louisiana State Museum. Submarines did not have a major impact on the outcome of the war, but did portend their coming importance to naval warfare and increased interest in their use in naval warfare.

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Mechanically-powered submarines (late 1800s)

Image:Plongeur.jpg The first submarine that did not rely on human power for propulsion was the French Navy submarine Plongeur, launched in 1863, and using compressed air at 180 psi <ref>Globalsecurity</ref>.

The first combustion-powered submarine was the steam and peroxide driven Ictineo II, launched in 1867 by Narcís Monturiol. It was originally launched in 1864 as a human-powered submarine, propelled by 16 men. <ref>Globalsecurity</ref>. Image:Ictineo II.jpgThe 14 meter long craft was designed to carry a crew of two, dive 30 metres (96 feet), and demonstrated dives of two hours. When on the surface it ran on a steam engine, but underwater such an engine would quickly consume the submarine's oxygen. So Monturiol turned to chemistry to invent an engine that ran on a reaction of potassium chlorate, zinc, and manganese peroxide. The beauty of this method was that the reaction which drove the screw released oxygen, which when treated was used in the hull for the crew and also fed an auxiliary steam engine that helped propel the craft under water. In spite of successful demonstrations in the Port of Barcelona, Monturiol was unable to interest the Spanish navy, or the navy of any other country.

In 1870, the French writer, Jules Verne, published the science fiction classic 20,000 Leagues under the Sea, which concerns the adventures of a maverick inventor in Nautilus, a submarine more advanced than any that existed at that time. The story inspired inventors to build more advanced submarines.

The first submarine built in series, however, was human-powered. It was the submarine of the Polish inventor Stefan Drzewiecki — 50 units were built in 1881 for Russian government. In 1884 the same inventor built an electric-powered submarine.

Discussions between the English reverend, George Garret, and the industrially and commercially adept Swede, Thorsten Nordenfelt, led to a series of steam powered submarines. The first was the Nordenfelt I, a 56 tonne, 19.5 metre long vessel similar to Garret's ill-fated Resurgam (1879), with a range of 240 kilometres and armed with a single torpedo in 1885. Like the Resurgam, it operated on the surface by steam, then it shut down its engine to dive. Greece, fearful of the return of the Ottomans, purchased it. Nordenfelt then built the Nordenfelt II, a 30 metre long submarine with twin torpedo tubes, which he sold to a worried Ottoman navy. Nordenfelt's efforts culminated in 1887 with the Nordenfelt IV, with twin motors and twin torpedoes. It was sold to Russians, but proved unstable, ran aground and was scrapped.

Image:Peral1888.jpg The first fully capable military submarine was the electrically powered vessel built by the Spanish engineer and sailor, Isaac Peral, for the Spanish Navy. It was launched on September 8 1888. It had two torpedoes, new air systems, a hull shape, propeller and cruciform external controls anticipating much later designs. Its underwater speed was ten knots, but it suffered from the short range of battery powered systems. In June 1890 Peral's submarine launched the first torpedo fired from a submarine under the sea. The Spanish Navy scrapped the project. Many more submarines were built at this time by various inventors, but they were not to become effective weapons until the 20th century.

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Late 1800s to World War I

Image:USS Plunger (SS-2).jpg The turn of century era marked a pivotal time in the development of submarines, with a number of important technologies making their debut, as well as the widespread adoption and fielding of submarines by a number of nations. Diesel electric propulsion would become the dominant power system and things such as the periscope would become standardized. Large numbers of experiments were done by countries on effective tactics and weapons for submarines, all of which would culminate in them making a large impact on coming World War I.

In 1895, the Irish inventor John Philip Holland designed submarines that, for the first time, made use of internal combustion engine power on the surface and electric battery power for submerged operations. In 1902, Holland received Template:US patent. Some of his vessels were purchased by the United States, the United Kingdom, the Imperial Russian Navy, and Japan, and commissioned into their navies around 1900.

Image:NarvalSubmarine.jpg Commissioned in June 1900, the French steam and electric submarine Narval introduced the classic double-hull design, with an pressure hull inside the outer light hull. These 200 tons ships had a range of over 100 miles on the surface, and over 10 miles underwater. The French submarine Aigrette in 1904 further improved the concept by using a diesel rather than a gasoline engine for surface power. Large numbers of these submarines were built, with seventy-six completed before 1914.

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Submarines during World War I

Image:U9Submarine.jpg The first time military submarines had significant impact on a war was in World War I. Forces such as the U-boats of Germany saw action in the First Battle of the Atlantic. The U-boats' ability to function as practical war machines relied on new tactics, their numbers, and submarine technologies such as combination diesel/electric power system that had been developed in the preceding years. More like submersible ships than the submarines of today, U-boats operated primarily on the surface using regular engines, submerging occasionally to attack under battery power. They were roughly triangular in cross-section, with a distinct keel, to control rolling while surfaced, and a distinct bow.

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Interwar developments

Image:HMS M2.jpg Various new submarine designs were developed during the interwar years. Among the most notorious ones were Submarine aircraft carriers, equipped with waterproof hangar and steam catapult and which could launch and recover one or more small seaplanes. The submarine and her plane could then act as a reconnaissance unit ahead of the fleet, an essential role at a time when radar still did not exist. The first example was the British HMS M2, followed by the French Surcouf, and numerous aircraft-carrying submarines in the Imperial Japanese Navy. The 1929 Surcouf was also designed as an "underwater cruiser," intended to seek and engage in surface combat.

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Submarines during World War II

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Germany

Germany had the largest submarine fleet during World War II. Due to the Treaty of Versailles limiting the surface navy, the rebuilding of the German surface forces had only begun in earnest a year before the outbreak of World War II. Having no hope of defeating the vastly superior Royal Navy decisively in a surface battle, the German High Command immediately stopped all construction on capital surface ships save the nearly completed Bismarck class battleships and two cruisers and switched the resources to submarines, which could be built more quickly. Though it took most of 1940 to expand the production facilities and get the mass production started, more than a thousand submarines were built by the end of the war.

Image:U-47s.jpg Germany put submarines to devastating effect in the Second Battle of the Atlantic in World War II, attempting but ultimately failing to cut off Britain's supply routes by sinking more ships than Britain could replace. The supply lines were vital to Britain for food and industry, as well as armaments from the USA. Although the U-boats had been updated in the intervening years, the major innovation was improved communications, encrypted using the famous Enigma cipher machine. This allowed for mass-attack tactics or "wolf packs", (Rudel), but was also ultimately the U-boats' downfall.

After putting to sea, the U-boats operated mostly on their own trying to find convoys in areas assigned to them by the High Command. If a convoy was found, the submarine did not attack immediately, but shadowed the convoy to allow other submarines in the area to find the convoy. These were then grouped into a larger striking force and attacked the convoy simultaneously, preferably at night while surfaced.

In the first half of the War the submarines scored spectacular successes with these tactics, but were too few to have any decisive success. In the second half Germany had enough submarines, but this was more than nullified by equally increased numbers of convoy escorts, aircraft, and technical advances like radar and sonar. Huff-Duff and Ultra allowed the Allies to route convoys around wolf packs when they detected them from their radio transmissions.

Winston Churchill wrote that the U-boat threat was the only thing that ever gave him cause to doubt the Allies' eventual victory.

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Japan

Main article: Imperial Japanese Navy submarines Image:I-400.jpg Japan had the most varied fleet of submarines of World War II, including manned torpedoes (Kaiten), midget submarines (Ko-hyoteki, Kairyu), medium-range submarines, purpose-built supply submarines (many for use by the Army), long-range fleet submarines (many of which carried an aircraft), submarines with the highest submerged speeds of the conflict (Sentaka I-200), and submarines that could carry multiple bombers (WWII's largest submarine, the Sentoku I-400). These submarines were also equipped with the most advanced torpedo of the conflict, the oxygen-propelled Type 95.

Overall, despite their technical prowess, Japanese submarines were relatively unsuccessful. They were often used in offensive roles against warships, which were fast, maneuverable and well-defended compared to merchant ships. In 1942, Japanese submarines sank two aircraft carriers among other warships, but were not able to sustain these results afterwards. By the end of the war, submarines were instead often used to transport supplies to island garrisons.

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United States

Image:USS Grayback (SS 208).jpg The United States used its submarine force to attack merchant shipping (commerce raiding or guerre de course), its submarines destroying more Japanese shipping than all other weapons combined.

Where Japan had the finest submarine torpedoes of the war, the USN had perhaps the worst, the Mark 14 steam torpedo, with a Mk 6 magnetic influence exploder and a Mk 5 contact exploder, neither of which was reliable. The depth control mechanism of the Mark 14 was corrected in August 1942, but field trials for the exploders were ordered only in mid-1943, when tests in Hawaii and Australia confirmed the flaws. One attempt to correct the poblems resulted in a wakeless, electric torpedo being placed in service, but the losses of the USS Tang and the USS Tullibee resulted from self-inflicted hits by these torpedoes, and the USS Wahoo may have been severely crippled by a circular hit on her bow before being bombed by aircraft.

During World War II, 314 submarines served in the United States Navy. 111 boats were in commission on 7 December 1941 and 203 submarines from the Gato, Balao, and Tench classes were commissioned during the war. 52 boats with 3,506 men were lost during hostilities. US submarines sunk 1,392 enemy vessels of a total tonnage of 5.3 million tons, including 8 aircraft carriers and over 200 warships.

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The schnorchel

Diesel submarines needed air to run their engines, and so carried very large batteries for submerged travel. These limited the speed and range of the submarines while submerged. The schnorchel (a prewar Dutch invention) was used to allow German submarines to run just under the surface, attempting to avoid detection visually and by radar. The German navy experimented with engines that would use hydrogen peroxide to allow diesel fuel to be used while submerged, but technical difficulties were great. The Allies experimented with a variety of detection systems, including chemical sensors to "smell" the exhaust of submarines.

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Modern submarines

In the 1950s, nuclear power partially replaced diesel-electric propulsion. Equipment was also developed to extract oxygen from sea water. These two innovations gave submarines the ability to remain submerged for weeks or months, and enabled previously impossible voyages such as USS Nautilus's crossing of the North pole beneath the Arctic ice cap in 1958. Most of the naval submarines built since that time in the United States and the Soviet Union/Russia have been powered by nuclear reactors. The limiting factors in submerged endurance for these vessels are food supply and crew morale in the space-limited submarine.

While the greater endurance and performance from nuclear reactors mean that nuclear submarines are better for long distance missions or the protection of a carrier battle-force, conventional diesel-electric submarines have continued to be produced by both nuclear and non-nuclear powers, as they can be made stealthier, except when required to run the diesel engine to recharge the ship’s battery. Technological advances in sound dampening, noise isolation and cancellation have substantially eroded this advantage. Though far less capable regarding speed and weapons payload, conventional submarines are also cheaper to build. The introduction of air-independent propulsion boats led to increased sales numbers of such types of submarines.

During the Cold War, the United States of America and the Soviet Union maintained large submarine fleets that engaged in cat-and-mouse games; this tradition today continues, on a much-reduced scale. The Soviet Union suffered the loss of at least four submarines during this period: K-129 was lost in 1968 (which CIA attempted to retrieve from the ocean floor with the Howard Hughes-designed ship named Glomar Explorer), K 8 in 1970, K -219 in 1986 (subject of the film "Hostile Waters"), and Komsomolets (the only Mike class submarine) in 1989 (which held a depth record among military submarines—1000 m). Many other Soviet subs, such as K-19 (first Soviet nuclear submarine, and first Soviet sub at North Pole) were badly damaged by fire or radiation leaks. The United States lost two nuclear submarines during this time: USS Thresher and Scorpion. The Thresher was lost due to equipment failure, and the exact cause of the loss of the Scorpion is not known.

Image:HMAS Collins (SSG 73).jpg Image:HMS Conqueror (S48).jpg The sinking of PNS Ghazi in the Indo-Pakistani War of 1971 was the first submarine casualty in the South Asian region. The United Kingdom employed nuclear-powered submarines against Argentina in 1982 during the two nations' Falklands War. The sinking of the antiquated cruiser ARA General Belgrano by HMS Conqueror was the first sinking by a nuclear-powered submarine in war.

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Major submarine incidents since 2000

Main Article: Major submarine incidents since 2000

Since submarines have been actively deployed, there have been several incidents involving submarines which were not part of major combat. Most of these incidents were during the Cold War, but some are more recent. Since the year 2000 there have been 9 major naval incidents involving submarines. There were three Russian submarine incidents, in two of which the submarines in question were lost, along with three United States submarine incidents, one Chinese incident, one Canadian, and one Australian incident. In August 2005, the Russian PRIZ, an AS-28 rescue submarine was trapped by cables and/or nets off of Petropavlovsk, and saved when a British ROV cut them free in a massive international effort.

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Submarine movies

Main article: Submarine film

A special genre of submarine movies has developed. Submarines are popular subjects for films due to the danger, drama and claustrophobia of being on a submarine, and the suspense of the cat-and-mouse game of submarine or anti-submarine warfare. These movies include The Hunt for Red October, Das Boot, U-571, Crimson Tide and The Enemy Below. K-19: The Widowmaker is about the first of many disasters that befell the Soviet submarine K-19.

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See also

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General

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Articles on specific vessels

Template:Groundbreaking submarines

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Articles on specific submarine classes

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Patents

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References

<references/>

  • "Steam, Steel and Shellfire, The steam warship 1815-1905", Conway's History of the Ship ISBN 0785814132
  • Blair, Clay Jr., Silent Victory: The U.S. Submarine War Against Japan, ISBN 1-55750-217-X
  • Lockwood, Charles A. (VAdm, USN ret.), Sink 'Em All: Submarine Warfare in the Pacific, (1951)
  • O'Kane, Richard H. (RAdm, USN ret.), Clear the Bridge!: The War Patrols of the USS Tang, ISBN 0-89141-346-4
  • O'Kane, Richard H. (RAdm, USN ret.), Wahoo: The Patrols of America's Most Famous WII Submarine, ISBN 0-89141-301-4
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External Links

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