Submarine

A submarine is a watercraft that can operate entirely underwater. The term submarine most commonly refers to large unaided vessels, however historically or more casually, submarine can also refer to medium sized or smaller vessels, (midget submarines, submersibles, wet subs) or robots. The word submarine was originally an adjective meaning "under the sea", and so consequently other usages such as 'submarine engineering' may not actually refer to submarines. Submarine was shortened from the term 'submarine boat'.

Submarines are referred to as "boats" for historical reasons, or commonly by the abbreviation 'sub'. The English term U-Boat for German submarine comes from the German word for submarine, `U-Boot`, itself an abbreviation for Unterseeboot ('undersea boat'). Most modern naval submarines are large enough to be equated with the definition of "ships".

Submarines were first widely used in World War I, and feature in many large navies. Military usage ranges from attacking enemy ships or submarines, aircraft carrier protection, blockade running, reconnaissance and covert insertion of special forces. Civilian uses for submarines include marine science, salvage, exploration and facility inspection/maintenance. Submarines can also be specialised to a function such as search and rescue or undersea cable repair. Submarines can also be used in tourism and for academic research.

Submarines have one of the largest ranges in capabilities of any vessel, ranging from small autonomous or one- or two-man vessels operating for a few hours, to vessels which can remain submerged for 6 months such as the Russian Typhoon class. Submarines can work at greater depths than are survivable or practical for human divers. Modern deep diving submarines are derived from the bathyscaphe, which in turn was an evolution of the diving bell.

Most large submarines comprise a cylindrical body with a vertical structure usually located amidships, which houses communications and sensing devices as well as periscopes. In modern submarines it is the "sail" in American usage ("fin" in European usage). A "conning tower" was a feature of earlier designs: a separate pressure hull above the main body of the boat that allowed the use of shorter periscopes. Smaller, deep diving and specialty submarines may deviate significantly from this traditional layout.

Military usage

Until the development of the homing torpedo after World War Two, the primary role of the diesel/electric submarine was anti-ship warfare, inserting and removing covert agents and military forces, and intelligence-gathering. They were also used in limited roles for artillery support or raids, and rescuing aircrews during large-scale air attacks on islands, where the aircrewmen would be told of safe places to crash-land damaged aircraft so the submarine crew could rescue them. The impact-detonated torpedoes of the era were difficult to use against a submarine because they ran a fixed course at a fixed depth, enabling the relatively small submarines to maneuver in three dimensions to avoid them.

With the development of the homing torpedo, better sonar systems, and nuclear propulsion, submarines also became able to effectively hunt each other as well as surface ships. The development of submarine-launched nuclear missiles and submarine-launched cruise missile gave submarines a substantial and long-ranged ability to attack both land and sea targets with a variety of weapons ranging from cluster bombs to nuclear weapons.

The primary offensive and defensive power of a submarine lies in its ability to remain concealed in the depths of the ocean. Modern submarines are built with an emphasis on stealth. Advanced propeller designs, extensive sound-reducing insulation, and special machinery allow a submarine to be as quiet as ambient ocean noise, making them extremely difficult to detect. Such submarines can launch an attack on land targets, surface ships, and other submarines from seemingly nowhere, and require specialized equipment to find and attack in retaliation. Water is an excellent conductor of sound, and submarines have excellent sonars that can detect and track comparatively noisy surface ships from long distances. This allows an attacking sub, at its discretion, to quietly maneuver to and attack from the best possible position at the best possible time.

A concealed submarine is a real threat, but because of its stealth, can force an enemy navy to waste resources searching large areas of ocean and protecting all ships against possible attack, while in reality only threatening a small area. This advantage was vividly demonstrated in the 1982 Falklands War when the British SSN HMS Conqueror sank the Argentine cruiser General Belgrano. After the sinking the Argentine Navy realised that they were vulnerable to submarine attack, and that they had no defense from it. Thus the Argentinian fleet remained in port for the remainder of the war.

Technology

Submersion and navigation

All surface ships, as well as surfaced submarines, are in a positively buoyant condition, weighing less than the volume of water they would displace if fully submerged. To submerge hydrostatically, a ship must gain negative buoyancy, either increasing its own weight or decreasing displacement of the water. 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. Under submerged conditions, 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 center of gravity, or separated along the submarine body to prevent affecting trim.

When submerged, the water pressure on submarine's hull can reach 4 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 either the depth control tanks or control surfaces.^[1]

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 moment 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 near 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/or 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 and Astute 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, infrared, laser range-finding, and electromagnetic surveillance.

Ship hull

Overview

Modern submarines are usually cigar-shaped. This design, already visible on very early submarines (see below) is sometimes called a "teardrop hull". 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 10kt (18 km·h⁻¹), 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.

The human-occupied pressure hulls of extremely deep diving submarines such as Alvin are spherical instead of the more traditional cylinder. This allows for a more even distribution of the stress at the great depths such subs operate at. A titanium frame is usually welded or bolted to the pressure hull to provide attachment points for ballast and trim systems, scientific instrumentation, battery packs, syntactic flotation foam, and lighting.

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 including the snorkel mast. 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.

Bathtubs are related to conning towers but are only for smaller submarines. A bathtub, in the context of smaller submarines, is a metal cylinder attached to the hull which surrounds the hatch and prevents waves from breaking directly into the cabin. Without one they would not be issued with a 'class'. It is needed because submarines on the surface don't have a lot of freeboard; they lie very low in the water. A Classification society issues the vessel class and has rules that must be followed to remain 'in class'. Vessels with no class have basically no chance at being insured.

Double hull

Modern submarines and submersibles, as well as the oldest ones, have a single hull. Large submarines generally have an additional hull or hull sections outside. This external hull, which actually forms the shape of submarine, is called the outer hull (casing in the Royal Navy) or light hull, as it does not have to hold any pressure difference. Inside the outer hull there is a strong hull, or pressure hull, which withstands sea pressure and has normal atmospheric pressure inside.

As early as World War I, it was realized that the optimal shape for withstanding pressure conflicted with the optimal shape for seaworthiness and minimized water resistance, and construction difficulties further complicated the problem. This was solved either by a compromise shape, or by using two hulls; internal for holding pressure, and external for optimal shape. Until the end of World War II, most submarines had an additional partial cover on the top, bow and stern, built of thinner metal, which was flooded when submerged. Germany went further with the Type XXI, the general predecessor of modern submarines, in which the pressure hull was fully enclosed inside the light hull, but optimised for submerged navigation, unlike earlier designs.

After World War II, approaches split. The Soviet Union changed its designs, basing them on the latest German developments. All post-WWII heavy Soviet and Russian submarines are built with a double hull structure. American and most other Western submarines retain a single-hull approach. They still have light hull sections in the bow and stern, which house main ballast tanks and provide a hydrodynamically optimized shape, but the main cylindrical hull section has only a single plating layer.

Despite being no longer needed for different shapes, the double-hull approach still has a number of advantages. The ring stiffeners and longitudinals are located between hulls, and the light hull can also be used to mount certain equipment that does not require constant pressure to operate, while attaching it directly to the pressure hull could cause dangerous local stress. These measures save a lot of space inside the pressure hull, which is much heavier and takes longer to build than the light hull. In case the submarine is damaged, the light hull can take most of the damage, which does not compromise the boat's integrity, as long as the strong hull is intact. A light hull can also be acoustically decoupled from the pressure hull, which significantly reduces noise from internal equipment, improves stealth or allows the use of a simpler internal layout and equipment mounting.

The major downside of double-hull structure is the significantly greater amount of manual work required to construct it. The Soviet Union had implemented the requisite welding technology earlier and had enough cheap qualified workers available, but the high cost of manual labor in the United States made the less expensive single-hull approach preferable. Another reason for double-hull construction in the Soviet Union was operation under the Arctic Ocean, where submarines had to break thick ice to launch their missiles, which could damage the hull. However, the double-hull approach is today being considered for future submarines in the United States as a means to improve payload capacity, stealth and operational reach.^[2]

Pressure hull

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. 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.

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 dive depths of up to 200 meters. High-strength alloyed steel is still the main material for submarines today, with 250-400 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 almost as strong as steel, but lighter, and is also not ferromagnetic, which is important for stealth. Titanium submarines were favored by the Soviet Union, which developed specialized high-strength alloys and built an industry capable of producing titanium at an affordable cost. It has produced several types of titanium submarines. Titanium alloys allow a major increase in depth, but other systems need to be redesigned to cope, so test depth was limited to 1000 meters for K-278 Komsomolets, the deepest-diving combat submarine. An Alfa class submarine may have successfully operated at 1300 meters,^[3] though continuous operation at such depths would be an excessive stress for many submarine systems. Despite its benefits, the high cost of titanium construction led to the abandonment of titanium submarine construction as the Cold War ended.

The task of building a pressure hull is very difficult, as it must withstand pressures of up to 10,000 psi. 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 (25 mm) deviation from roundness results in over 30 percent decrease of maximal hydrostatic load and consequently dive depth.^[4] 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 the very high cost of modern submarines. (For example, each Virginia-class attack submarine costs 2.6 billion dollars, over $200,000 per ton of displacement.)

Propulsion

The first mechanically driven submarine was the 1863 French Plongeur, which used compressed air for propulsion, and anaerobic propulsion was first employed by the Spanish Ictineo II in 1864. Ictineo's engine used a chemical mix containing a peroxide compound to generate heat for steam propulsion while also providing oxygen for the crew. 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.

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 submarines used gasoline, but this quickly gave way to paraffin, then diesel, because of reduced flammability. Diesel-electric became the standard means of propulsion. The diesel or gasoline engine and the electric motor, separated by clutches, were initially on the same shaft and drove the propeller. 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 submarine dove so that the motor could be used to turn the propeller. The motor could have more than one armature on the shaft, and these could be electrically coupled in series for slow speed and in parallel for high speed. (These alternative connections were known as "group down" and "group up", respectively.)

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

Other power sources were attempted. Oil-fired steam turbines powered the British "K" class submarines, built during the first World War and in the following years, with the intent of giving them the necessary surface speed to keep up with the British battle fleet. The "K" class subs were not very successful, however. (The design was also over-endowed with hatches, which proved troublesome in service.) German Type XXI submarines attempted the application of hydrogen peroxide to provide long-term, fast air-independent propulsion, but were ultimately built with very large batteries instead.

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 (codenamed Quebec by NATO), they were considered unsuccessful. Today several navies use air-independent propulsion. Notably Sweden uses Stirling technology on the Gotland class and Södermanland class series of submarines. The Stirling engine is heated by burning diesel fuel with liquid oxygen stored in cryogenic tanks. A newer development in air-independent propulsion is the use of hydrogen fuel cells, first applied in series on the German Type 212 submarine, with nine 34 kW or two 120-kilowatt cells.

Steam power was resurrected in the 1950s with the advent of the nuclear-powered steam turbine driving a generator. By removing the requirement for atmospheric oxygen, these submarines can remain submerged indefinitely. (Air is recycled and fresh water is 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.

Nuclear power is now used in all large submarines, but due to the high cost and large size of nuclear reactors, smaller submarines still use diesel-electric propulsion. The ratio of larger to smaller submarines depends on strategic needs; for instance, the US Navy operates only nuclear submarines,^[5] which is usually explained by the need for overseas operations. Other major operators rely on a mix of nuclear submarines for strategic purposes and diesel-electric submarines for defensive needs. Most fleets have no nuclear submarines at all, due to the limited availability of nuclear power and submarine technology. Commercial submarines usually rely only on batteries, as they are never expected to operate independently of a mother ship.

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

The magnetohydrodynamic drive, or "caterpillar drive", which has no moving parts was popularized as a submarine propulsion system by the movie version of The Hunt for Red October, written by Tom Clancy, which portrayed it as a virtually silent system.

Although experimental surface ships have been built with this propulsion system, speeds have not been as high as expected. In addition, the drive system can induce bubbles to form, compromising stealth, and the low efficiency leads to very high required reactor powers. These factors make it unlikely to be considered for any military purpose.

Armament

The success of the submarine is inextricably linked to the development of the torpedo, invented by the English engineer Robert Whitehead in 1866. His invention is essentially the same today as it was 100 years ago. Only with the arrival of self propelled torpedoes could the submarine make the leap from mechanical novelty into a weapon of war. Until the perfection of the guided torpedo, multiple torpedoes of the straight running kind were required to attack a target. With at most 20 to 25 torpedoes the number of attacks that could be made was limited. To increase combat endurance most submarines of the First World War functioned as submersible gunboats, using their deck guns against unarmed targets and diving to escape and engage enemy warships. The importance of guns encouraged the development of the unsuccessful Submarine Cruiser such as the French Surcouf and the Royal navy's X1 and M class submarines. With the arrival of ASW aircraft, guns became more of means of defence than of attack. A more practical method of increasing combat endurance was the external torpedo tube which could only be loaded in port.

The ability of submarines to approach enemy harbors led to their use as minelayers. Minelaying submarines of the First and Second World War were specially built for that purpose. Modern submarine-laid mines, such as the British Mark 6 Sea Urchin, are designed to be deployed by a submarine's torpedo tubes.

Post World War 2 both the USA and the USSR experimented with submarine launched cruise missiles such as the SSM-N-8 Regulus and P-5 Pyatyorka however with such missiles the submarine had to surface to fire its missiles. Such missiles were the fore runners of modern submarine launched cruise missiles which can be fired from the torpedo tubes of submerged submarines e.g. the US BGM-109 Tomahawk and Russian RPK-2 Viyuga. Conventional missiles can also be fired from a submarine's torpedo tubes, for example missiles such as the anti-submarine SUBROC, and versions of surface to surface anti-ship missiles such as the Exocet and Harpoon, encapsulated for submarine launch. With internal volume as limited as ever and the desire to carry heavier warloads, the idea of the external launch tube was revived, usually for the encapsulated missiles and such tubes being placed in the space between the internal pressure and outer streamlined hulls.

Crew

Overview

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 an amine absorbent 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 either an evaporator or a reverse osmosis unit. It is used for showers, sinks, cooking and cleaning. Seawater is used to flush toilets, and the resulting "black water" is stored in a sanitary tank until it is blown overboard using pressurised air or pumped overboard by using a special sanitary pump. The method for blowing sanitaries overboard 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 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 80; non-nuclear boats typically have fewer than half as many. The conditions on a submarine can be difficult because crewmembers 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.

Women as part of crew

In 1995 the Royal Norwegian Navy became the first navy in the world to appoint a female submarine captain.^[6] In 1998, the Royal Australian Navy (RAN) became the second navy to allow women to serve on combat submarines. Canada and Spain followed in permitting women to serve on military submarines with seamen.^[7] The usual reasons for barring women that are given are lack of privacy and "hot bunking" or "hot racking", a common practice on submarines where three sailors share two bunks on a rotating basis to save space. The US Navy, which permits women to serve on almost every other ship in the fleet, only allows three exceptions for women being on board military submarines: (1) Female civilian technicians for a few days at most; (2) Women midshipmen on an overnight during summer training for both Navy ROTC and Naval Academy; (3) Family members for one-day dependent cruises.^[8] The US Navy argues it would cost $300,000 per bunk to permit women to serve on submarines versus $4,000 per bunk to allow women to serve on aircraft carriers. However, this calculation is based on the assumption of semi segregation of the female crew, possibly to the extent of structural redesign of the vessel.^[9] No studies of the feasibility of an all-female crew, which would circumvent the US Navy's objections, are known to have been carried out. It should be noted that a brand new submarine crew would have little experience in operating a modern nuclear submarine. Since most of the US Navy's work related training is on-the-job training, an all-female crew is not in the Navy's foreseeable future.

The Royal Navy (RN) also has medical concerns about women (the safety of the fetus and hence its mother) sailing on board a nuclear boat, this is more to do with contaminants in the submarine's atmosphere than radiation. Also if a female crewmember of a surface ship becomes pregnant, she can be "dropped" at almost any time whereas for operational safety a UK SSBN does not surface till the end of its deployment that could take several months, so the female would not be able to transfer off the boat.

History of submarines

Early history of submarines and the first submersibles

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 of England. It inspired by the design outlined by English mathematician William Bourne. 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. In 2002 a two-man version of Drebbel's design was built for the BBC TV programme Building the Impossible by Mark Edwards, and successfully rowed under water at Dorney Lake, Eton.

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, England, in Mathematicall Magick in 1648.

The first military submarines

The first military submarine was Turtle (1775), 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.

In 1800, France built a human-powered submarine designed by Robert Fulton, the Nautilus. The French eventually gave up with the experiment in 1804, as did the British when they later considered Fulton's submarine design.

During the War of 1812, in 1814, Silas Halsey lost his life while using a submarine in an 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 (incendiary-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.

Submarines in the American Civil War

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. It 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, it was converted after 6 months to a screw propeller powered by a hand crank. With a crew of 20, it was larger than Confederate submarines. Alligator was 47 feet (14.3 m) long and about 4 feet (1.2 m) in diameter. It was lost in a storm off Cape Hatteras on April 1, 1863 while uncrewed and under tow to its first combat deployment at Charleston.

The Confederate States of America fielded several man-powered submarines including H. L. Hunley (named for one of its financiers, Horace Lawson Hunley) . The first Confederate submarine was the 30-foot (9 m) long Pioneer which sank a target schooner using a towed mine during tests on Lake Pontchartrain but it was not used in combat. It was scuttled after New Orleans was captured and in 1868 was sold for scrap.

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 it sank in the same engagement shortly after signaling its success. Another Confederate submarine was lost on its maiden voyage in Lake Pontchartrain; it 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.

South America

The first submarine was the "Hipopotamo", tested in Ecuador in September 18, 1837. It was built by Jose Rodriguez Lavandera, who successfully crossed the Guayas river in Guayaquil accompanied by Jose Quevedo. Rodriguez Lavandera enrolled in the Navy in 1823, becoming a Liutenant by 1830. The "Hipopotamo" crossed the Guayas on two more occasions, but it was then abandoned because of lack of funding and interest from the government.

Later on, the "Flach", commissioned in 1865 by the Chilean government during the war between Chile and Peru against Spain (1864-1866). It was built by the German engineer Karl Flach. The submarine sank during tests in Valparaiso bay on May 3, 1866, with the entire eleven-man crew.

Mechanically-powered submarines (late 19th century)

The first submarine not relying on human power for propulsion was the French Plongeur, launched in 1863, and using compressed air at 180 psi.^[10]

The first combustion-powered submarine was Ictineo II, designed in Spain by Narcís Monturiol. Originally launched in 1864 for human-power, propelled by 16 men,^[10] it was converted to peroxide propulsion and steam in 1867. The 14 meter (46 ft)-long craft was designed for a crew of two, dive 30 metres (96 ft), and demonstrated dives of two hours. On the surface it ran on a steam engine, but underwater such an engine would quickly consume the submarine's oxygen, so Monturiol invented an anaerobic engine. The beauty of this method was, while the engine drove the screw it also released oxygen which was used in the hull for the crew and also fed an auxiliary steam engine.

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 at the time. The story inspired inventors to build more advanced submarines.

In 1879, the Peruvian government, during the War of the Pacific commissioned and built a submarine, the fully operational Toro Submarino. It never saw military action before being scuttled after the defeat of that country in the war to prevent its capture by the enemy. 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 the Russian government. In 1884 the same inventor built an electric-powered submarine.

Nordenfelt-designed Ottoman submarine Abdülhamid (1886) was the first submarine in the world to fire a torpedo while submerged. It and its sister ship, Abdülmecid (1887), were built in pieces by Des Vignes (Chertsey) and Vickers (Sheffield) in England, and were assembled at the Taşkızak Naval Shipyard in Istanbul, Turkey.

Nordenfelt-designed Ottoman submarine Abdülhamid (1886) was the first submarine in the world to fire a torpedo while submerged.^[11] It and its sister ship, Abdülmecid (1887), were built in pieces by Des Vignes (Chertsey) and Vickers (Sheffield) in England, and were assembled at the Taşkızak Naval Shipyard in Istanbul, Turkey.

Discussions between the English clergyman and inventor, George Garrett, 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 (64 ft)-long vessel similar to Garret's ill-fated Resurgam (1879), with a range of 240 kilometres (150mi, 130 nm), armed with a single torpedo, in 1885. Like Resurgam, Nordenfelt I operated on the surface by steam, then shut down its engine to dive. Underwater the submarine released pressure generated when the engine was running on the surface to provide propulsion for some distance underwater. Greece, fearful of the return of the Ottomans, purchased it. Nordenfelt then built Nordenfelt II (Abdülhamid) in 1886 and Nordenfelt III (Abdülmecid) in 1887, a pair of 30 metre (100 ft)-long submarines with twin torpedo tubes, for the Ottoman navy. Abdülhamid became the first submarine in history to fire a torpedo submerged.^[12] Nordenfelt's efforts culminated in 1887 with Nordenfelt IV which had twin motors and twin torpedoes. It was sold to the Russians, but proved unstable, ran aground and was scrapped.

On the 8th September, 1888, an electrically powered vessel built by the Spanish engineer and sailor, Isaac Peral, for the Spanish Navy was launched. It had two torpedoes, new air systems, and a hull shape, propeller, and cruciform external controls anticipating much later designs. Its underwater speed was ten knots (19 km/h). In June 1890 Peral's submarine launched a torpedo while submerged. Its ability to fire torpedoes under water while maintaining full propulsive power and control has led some to call it the first U-boat.

After many successful dives the project was scrapped because of the difficulties of recharging at sea and the short range of battery powered vessels.

Shortly after the French Gymnote, was launched 24 September 1888, another fully functional military submarine. The electrically-powered Gymnote completed 2,000 dives successfully.

Many more designs were built at this time by various inventors, but submarines were not to become effective weapons until the 20th century.

Late 19th century to World War I

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 the 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. On 11 April 1900 the United States Navy purchased the Holland VI and renamed it the USS Holland/SS-1, America's first commissioned submarine. In 1902, Holland received a patent. ^[13] 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 (1905 for Japan, too late to serve in the Russo-Japanese War).

Commissioned in June 1900, the French steam and electric submarine Narval introduced the classic double-hull design, with a pressure hull inside the outer light hull. These 200-ton 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.

Submarines during World War I

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 developed in the preceding years. More submersibles than true submarines, 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.

In 1916, two Serbian pilots, Dimitrije Konjović and Walter Zelezny of the Austro-Hungarian air service, bombed and sank French submarine Foucault in the Adriatic, thus becoming the first to sink a submarine from the air. Spotting survivors in the water, they landed their flying boats and rescued all of them, an act for which the French government awarded Konjovic special recognition in 1968.

Interwar developments

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 its 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",

Submarines during World War II

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. Expecting to be able to defeat the Royal Navy through underwater warfare, 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.

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", (Wolfsrudel), 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.

From September 1939 to the beginning of 1943, the Ubootwaffe ("U-boat weapon") scored unprecedented success with these tactics, but were too few to have any decisive success. By the spring of 1943, German U-boat construction was at full capacity, but this was more than nullified by increased numbers of convoy escorts, aircraft, as well as 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. The results were devastating: from March to July of that year, over 130 U-boats were lost, 41 in May alone. Concurrent Allied losses dropped dramatically, from 750,000 tons in March, to only 188,000 in July. Although the Second battle of the Atlantic would continue to the last day of the war, the U-boat arm was unable to stem the tide of men and material, paving the way for Operation Torch, Operation Husky, and ultimately, D-Day.

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

Japan

Japan started their submarine service with five Holland Type VII Class submarines originally built at the Fore River Ship and Engine Company located in Quincy, Ma. The country purchased five submarines from the Electric Boat Company now being run by "outersider" who included Isaac Leopold Rice and other men "of means". These five submarines were developed under the watchful sight of Arthur l. Busch.

Japan had the most varied fleet of submarines of World War II, including manned torpedoes (Kaiten manned torpedo), 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 (Sen taka I-200 class submarine), and submarines that could carry multiple bombers (WWII's largest submarine, the Sen toku I-400 class submarine). These submarines were also equipped with the most advanced torpedo of the conflict, the oxygen-propelled Type 95.

Nevertheless, 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.

United States

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. This feat was considerably aided by the Japanese refusal to provide escorts for its Merchant Fleet until very late in the war.

Whereas Japan had the finest submarine torpedoes of the war, the United States Navy had the worst: the Mark 14 torpedo that ran ten feet too deep tipped with its Mk VI exploder that was based on an unimproved version of the Mark V contact exploder but with an additional magnetic exploder, neither of which was reliable. The faulty 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. Fully operational Mark 14 torpedoes weren't put into service until September, 1943. The Mark 15 torpedo used by US surface combatants had the same Mk VI exploder and wasn't fixed until late 1943. One attempt to correct the problems resulted in a wakeless, electric torpedo being placed in submarine service, but the losses of USS Tang and Tullibee resulted from self-inflicted hits by these torpedoes.

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, the highest KIA percentage of any US service arm in WWII. US submarines sank 1,392 enemy vessels, a total tonnage of 5.3 million tons, including 8 aircraft carriers and over 200 warships.

United Kingdom

The Royal Navy Submarine Service was primarily used to enforce the classic British blockade role. It therefore chiefly operated in inshore waters and tended to only surface by night.

Its major operating areas were around Norway, the Mediterranean (against the Axis supply routes to North Africa) and in the Far East. RN submarines operating out of Trincomalee and Australia were a constant threat to Japanese shipping passing through the Malacca Straits.

In the war British submarines sank 2 million tons of enemy shipping and 57 major warships; the latter including 35 submarines. Amongst these is the only instance ever of a submarine sinking another submarine while both were submerged. This occurred when HMS Venturer engaged the U864; the Venturer crew manually computed a successful firing solution against a three-dimensionally manoeveuring target using techniques which became the basis of modern torpedo computer targeting computer systems.

The Snorkel

Diesel submarines need 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 snorkel (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.

Cold war diesel electric submarines, such as the Oberon class, used the batteries to power the motors so they ran silently. They recharged the batteries using the diesel engines without ever surfacing.

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' crossing of the North pole beneath the Arctic ice cap in 1958 ^[15]and the U.S.S. Triton's submerged circumnavigation of the world in 1960^[16]. 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 damping, 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 the 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, 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 (the first Soviet nuclear submarine, and the first Soviet sub to reach the North Pole) were badly damaged by fire or radiation leaks. The United States lost two nuclear submarines during this time: USS Thresher and Scorpion. Thresher was lost due to equipment failure during a test dive while at its operational limit, and the exact cause of the loss of Scorpion is not known, though it is thought by many to have been a faulty torpedo.

PNS' Hangor was a Pakistani Daphne class submarine, which during the 1971 Indo-Pakistani War sank the Indian frigate INS Khukri. This was the first submarine kill since World War II, and the only one until the United Kingdom employed nuclear-powered submarines against Argentina in 1982 during the two nations' Falklands War: the sinking of the cruiser General Belgrano by HMS Conqueror (which was the first sinking by a nuclear-powered submarine in war). Pakistani PNS Ghazi was a Tench class submarine on loan from US USS Diablo (SS/AGSS-479) was lost in Indo-Pakistani War of 1971 near Visakhapatnam, it was the first submarine casualty since World War II during war time.

More recently Russia has had 2 high profile submarine accidents the Kursk K-141 and the K-159 on 30 August 2003 . The Kursk went down with all hands whereas K-159 was being towed to a scrap yard and only 9 of 10 died, this sinking was big news in Russia as it was anouther submarine disaster for Putin and his government as it happened almost 3 years to the day to the Kursk accident. The sinking was put down to incompetence by senior naval officers and very bad weather.

Submarines in popular culture

Fiction books

Television

Film

A 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. One of the first, based on a classic book, was Run Silent, Run Deep. More modern 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. Operation Petticoat is a Cary Grant comedy from 1959 about a World War II submarine. Another comedy about a diesel submarine, Down Periscope, stars Kelsey Grammer. The James Bond movie The Spy Who Loved Me featured a Royal Navy ballistic missile sub being stolen by a shipping tycoon to be used in his plot for world domination.

Games

Music

Contents

Military usage

Technology

Submersion and navigation

Ship hull

Overview

Double hull

Pressure hull

Propulsion

Armament

Crew

Overview

Women as part of crew

History of submarines

Early history of submarines and the first submersibles

The first military submarines

Submarines in the American Civil War

South America

Mechanically-powered submarines (late 19th century)

Late 19th century to World War I

Submarines during World War I

Interwar developments

Submarines during World War II

Germany

Japan

United States

United Kingdom

The Snorkel

Modern submarines

Submarines in popular culture

Fiction books

Television

Film

Games

Music

See also

Submarine articles

Related topics

Articles on specific vessels

Articles on specific submarine classes

Patents

References

External links