A submarine is a watercraft capable of independent operation underwater. It differs from a submersible, which has more limited underwater capability. The term is also sometimes used historically or colloquially to refer to remotely operated vehicles and robots, as well as medium-sized or smaller vessels, such as the midget submarine and the wet sub. Submarines are referred to as boats rather than ships irrespective of their size.
U-boats were naval submarines operated by Germany, particularly in the First and Second World Wars. The term is an anglicized version of the German word U-Boot, a shortening of Unterseeboot, though the German term refers to any submarine. Austro-Hungarian Navy submarines were also known as U-boats.
An attack submarine or hunter-killer submarine is a submarine specifically designed for the purpose of attacking and sinking other submarines, surface combatants and merchant vessels. In the Soviet and Russian navies they were and are called "multi-purpose submarines". They are also used to protect friendly surface combatants and missile submarines. Some attack subs are also armed with cruise missiles, increasing the scope of their potential missions to include land targets.
The Alfa class, Soviet designation Project 705 Lira, was a class of nuclear-powered attack submarines in service with the Soviet Navy from 1971 into the early 1990s, with one serving later with the Russian Navy until 1996. They were among the fastest military submarines ever built, with only the prototype submarine K-222 exceeding them in submerged speed.
Hellmuth Walter was a German engineer who pioneered research into rocket engines and gas turbines. His most noteworthy contributions were rocket motors for the Messerschmitt Me 163 and Bachem Ba 349 interceptor aircraft, so-called Starthilfe jettisonable rocket propulsion units used for a variety of Luftwaffe aircraft during World War II, and a revolutionary new propulsion system for submarines known as air-independent propulsion (AIP).
The Tang-class submarines were the first submarines designed and built by the United States Navy after WWII. They incorporated the best features of the high-speed German Type XXI U-boat and the venerable U.S. Navy fleet submarine. The Tang-class, with the fleet submarines converted under the Greater Underwater Propulsion Power (GUPPY) program, had much higher submerged performance than their predecessors, but were quickly surpassed by the nuclear-propelled submarines that entered service beginning in 1954. Six units in total were built.
A midget submarine is any submarine under 150 tons, typically operated by a crew of one or two but sometimes up to six or nine, with little or no on-board living accommodation. They normally work with mother ships, from which they are launched and recovered and which provide living accommodation for the crew and support staff.
High-test peroxide (HTP) is a highly concentrated solution of hydrogen peroxide, with the remainder consisting predominantly of water. In contact with a catalyst, it decomposes into a high-temperature mixture of steam and oxygen, with no remaining liquid water. It was used as a propellant of HTP rockets and torpedoes, and has been used for high-performance vernier engines.
Air-independent propulsion (AIP), or air-independent power, is any marine propulsion technology that allows a non-nuclear submarine to operate without access to atmospheric oxygen. AIP can augment or replace the diesel-electric propulsion system of non-nuclear vessels.
An Elektroboot was a submarine designed to operate entirely submerged, rather than as submersibles that could submerge as a temporary means to escape detection or launch an attack.
The history of the submarine goes back to antiquity. Humanity has employed a variety of methods to travel underwater for exploration, recreation, research and significantly, warfare. While early attempts, such as those by Alexander the Great, were rudimentary, the advent of new propulsion systems, fuels, and sonar, propelled an increase in submarine technology. The introduction of the diesel engine, then the nuclear submarine, saw great expansion in submarine use – and specifically military use – during World War I, World War II, and the Cold War. The Second World War use of the U-Boat by the Kriegsmarine against the Royal Navy and commercial shipping, and the Cold War's use of submarines by the United States and Russia, helped solidify the submarine's place in popular culture. The latter conflicts also saw an increasing role for the military submarine as a tool of subterfuge, hidden warfare, and nuclear deterrent. The military use of submarines continues to this day, predominantly by North Korea, China, the United States and Russia.
HMS Explorer was an Explorer-class submarine, an experimental British submarine based on the captured German high test peroxide (HTP) powered U-boat U-1407. U-1407 had been scuttled following the German collapse at the end of the Second World War, was salvaged and eventually commissioned into the Royal Navy as HMS Meteorite. Her recovery was the impetus for a British research programme which resulted in the construction of two experimental submarines, HMS Explorer and HMS Excalibur. Built for speed trials, they were unarmed. Their HTP engines were essentially steam turbines, with the steam being generated by the interaction of HTP with diesel oil and a catalyst.
HMS Meteorite was an experimental U-boat developed in Germany, scuttled at the end of World War II, subsequently raised and commissioned into the Royal Navy. The submarine was originally commissioned into the Kriegsmarine on 13 March 1945 as U-1407. She was built around a Walter engine fueled by high-test peroxide (HTP), the fuel known as T-Stoff in German service.
The Type XVII U-boats were small coastal submarines that used a high-test peroxide propulsion system, which offered a combination of air-independent propulsion and high submerged speeds.
HMS Excalibur was an Explorer-class submarine, the sister ship of HMS Explorer, the two submarines being the only high-test peroxide (HTP) powered submarines to be constructed for the Royal Navy. She is the only ship to be named as such, in honour of the sword of Arthurian legend.
The R-class submarines were a class of 12 small British diesel-electric submarines built for the Royal Navy during World War I, and were forerunners of the modern attack submarine, in that they were designed specifically to attack and sink enemy submarines, their battery capacity and hull shape being optimized for underwater performance.
Marine propulsion is the mechanism or system used to generate thrust to move a watercraft through water. While paddles and sails are still used on some smaller boats, most modern ships are propelled by mechanical systems consisting of an electric motor or internal combustion engine driving a propeller, or less frequently, in pump-jets, an impeller. Marine engineering is the discipline concerned with the engineering design process of marine propulsion systems.
A teardrop hull is a submarine hull design which emphasizes submerged performance over surfaced performance. It was somewhat commonly used in the early stages of submarine development, but was gradually abandoned in the early 20th century in favour of designs optimized for high performance on the surface as a result of changes in operational doctrine. Although naval doctrine changed, design practices remained until the later parts of World War II when the German Kriegsmarine suffered ever-growing losses of submarines in the Battle of the Atlantic.
The S-99 experimental submarine was the only ship of the Project 617 class that the Soviet Union built during the early Cold War. She was the only Soviet submarine which used a German Walter turbine fueled by high-test peroxide (HTP). Entering service in 1956, the boat was assigned to a training unit of the Baltic Fleet. S-99 was badly damaged by a HTP explosion in 1959 and was not repaired. The submarine was decommissioned in 1964 and subsequently scrapped.
There have been a number of 21-inch (53.3cm) torpedoes in service with the Royal Navy of the United Kingdom.
