A scuba set, originally just scuba, is any breathing apparatus that is entirely carried by an underwater diver and provides the diver with breathing gas at the ambient pressure. Scuba is an anacronym for self-contained underwater breathing apparatus. Although strictly speaking the scuba set is only the diving equipment that is required for providing breathing gas to the diver, general usage includes the harness or rigging by which it is carried and those accessories which are integral parts of the harness and breathing apparatus assembly, such as a jacket or wing style buoyancy compensator and instruments mounted in a combined housing with the pressure gauge. In the looser sense, scuba set has been used to refer to all the diving equipment used by the scuba diver, though this would more commonly and accurately be termed scuba equipment or scuba gear. Scuba is overwhelmingly the most common underwater breathing system used by recreational divers and is also used in professional diving when it provides advantages, usually of mobility and range, over surface-supplied diving systems and is allowed by the relevant legislation and code of practice.
The timeline of underwater diving technology is a chronological list of notable events in the history of the development of underwater diving equipment. With the partial exception of breath-hold diving, the development of underwater diving capacity, scope, and popularity, has been closely linked to available technology, and the physiological constraints of the underwater environment.
Aqua-Lung was the first open-circuit, self-contained underwater breathing apparatus to achieve worldwide popularity and commercial success. This class of equipment is now commonly referred to as a twin-hose diving regulator, or demand valve. The Aqua-Lung was invented in France during the winter of 1942–1943 by two Frenchmen: engineer Émile Gagnan and Jacques Cousteau, who was a Naval Lieutenant. It allowed Cousteau and Gagnan to film and explore underwater more easily.
A frogman is someone who is trained in scuba diving or swimming underwater in a tactical capacity that includes military, and in some European countries, police work. Such personnel are also known by the more formal names of combat diver, combatant diver, or combat swimmer. The word frogman first arose in the stage name the "Fearless Frogman" of Paul Boyton in the 1870s and later was claimed by John Spence, an enlisted member of the U.S. Navy and member of the OSS Maritime Unit, to have been applied to him while he was training in a green waterproof suit.
A full-face diving mask is a type of diving mask that seals the whole of the diver's face from the water and contains a mouthpiece, demand valve or constant flow gas supply that provides the diver with breathing gas. The full face mask has several functions: it lets the diver see clearly underwater, it provides the diver's face with some protection from cold and polluted water and from stings, such as from jellyfish or coral. It increases breathing security and provides a space for equipment that lets the diver communicate with the surface support team.
The Clearance Divers Breathing Apparatus (CDBA) is a type of rebreather made by Siebe Gorman in England.
A clearance diver was originally a specialist naval diver who used explosives underwater to remove obstructions to make harbours and shipping channels safe to navigate, but the term "clearance diver" was later used to include other naval underwater work. Units of clearance divers were first formed during and after World War II to clear ports and harbours in the Mediterranean and Northern Europe of unexploded ordnance and shipwrecks and booby traps laid by the Germans.
The Russian commando frogmen, informally called "commando frogmen" in civilian media, are a Russian Naval Spetsnaz unit under operational subordination to the Main Intelligence Directorate (GRU). It is the special forces unit of the Russian Naval Infantry and is composed of highly trained and elite marines within the Naval Infantry. By virtue of belonging to the Russian Naval Infantry, frogmen fall under the Coastal Troops of the Russian Navy service arm. The Russian Navy proper does not field any special forces or special operations units. Russian FSB special forces Alpha Group and Vympel also have frogman units in their respective naval components.
Underwater Port Security System (UPSS) was developed for the United States Coast Guard and the Maritime Safety and Security Teams (MSSTs) for defense against swimmer incursions. It includes the Underwater Inspection System (UIS) and the Integrated Anti-Swimmer System (IAS). Recent developments in terrorism have highlighted the need for underwater anti-frogman security. The UPSS is made in the United States and is reported to be compact enough fit in a large suitcase.
Cerberus is an ultrasound diver detection sonar to detect submerged divers. Mod 1 was made by Qinetiq, in their underwater business division. It was unveiled at UDT 2003. The underwater division was sold to ATLAS ELEKTRONIK UK in 2009 and the Mod 2 version was developed by them. It is semi-intelligent and reportedly can detect an air-filled chest cavity underwater and let its operator tell whether the echo is from a man or something irrelevant such as a seal or dolphin, and to distinguish between: a shoal of fish; a ship's wake; a diver with an open-circuit scuba set; a stealth diver with a rebreather; flotsam and jetsam.
The US employs divers in several branches of the armed forces, including the navy, army, marines, air force and coast guard.
Diver detection sonar (DDS) systems are sonar and acoustic location systems employed underwater for the detection of divers and submerged swimmer delivery vehicles (SDVs). The purpose of this type of sonar system is to provide detection, tracking and classification information on underwater threats that could endanger property and lives. Further, this information is useful only to the extent that it is made available to authorities in time to make possible the desired response to the threat, be it deterrent or defensive action. Subsurface threats are a difficult problem, because reliable detection is available to date chiefly by use of high-resolution active sonar or trained dolphins or sea lions. The threat of an underwater terrorist attack is a concern to the maritime industry and port law enforcement agencies. Ports face a range of threats from swimmers, boat-delivered ordnance such as limpet mines and other forms of improvised underwater explosive devices. DDS systems have been developed to provide underwater security for ports, coastal facilities, offshore installations, pipelines and ships. Due to the variety of life and objects that exist under the water, it is desirable that a DDS system be capable of distinguishing between large sea mammals, shoals of fish; a ship's wake; a diver with an open circuit scuba set and a stealth diver with a rebreather. DDS systems have been developed that can be mounted on the seabed, on a pier or on the hull of a vessel. For complete port security these systems are integrated with the surface surveillance and security systems employed at ports, coastal facilities and offshore installations. Various systems provide specialized features to facilitate their use in port security systems including automatic detection features.
Aqua Lung International is a large and well-known firm which makes scuba and other self-contained breathing apparatus, and other diving equipment. It produced the Aqua-Lung line of regulators, like the CG45 (1945) and the Mistral (1955), among others. Until 2016, the company was a division of Air Liquide since its foundation in 1946. The company was sold to Montagu Private Equity in 2016.
The Lambertsen Amphibious Respiratory Unit (LARU) is an early model of closed circuit oxygen rebreather used by military frogmen. Christian J. Lambertsen designed a series of them in the US in 1940 and in 1944.
Underwater breathing apparatus is equipment which allows the user to breathe underwater. The three major categories of ambient pressure underwater breathing apparatus are:
Underwater searches are procedures to find a known or suspected target object or objects in a specified search area under water. They may be carried out underwater by divers, manned submersibles, remotely operated underwater vehicles, or autonomous underwater vehicles, or from the surface by other agents, including surface vessels, aircraft and cadaver dogs.
The history of scuba diving is closely linked with the history of the equipment. By the turn of the twentieth century, two basic architectures for underwater breathing apparatus had been pioneered; open-circuit surface supplied equipment where the diver's exhaled gas is vented directly into the water, and closed-circuit breathing apparatus where the diver's carbon dioxide is filtered from the exhaled breathing gas, which is then recirculated, and more gas added to replenish the oxygen content. Closed circuit equipment was more easily adapted to scuba in the absence of reliable, portable, and economical high pressure gas storage vessels. By the mid-twentieth century, high pressure cylinders were available and two systems for scuba had emerged: open-circuit scuba where the diver's exhaled breath is vented directly into the water, and closed-circuit scuba where the carbon dioxide is removed from the diver's exhaled breath which has oxygen added and is recirculated. Oxygen rebreathers are severely depth limited due to oxygen toxicity risk, which increases with depth, and the available systems for mixed gas rebreathers were fairly bulky and designed for use with diving helmets. The first commercially practical scuba rebreather was designed and built by the diving engineer Henry Fleuss in 1878, while working for Siebe Gorman in London. His self contained breathing apparatus consisted of a rubber mask connected to a breathing bag, with an estimated 50–60% oxygen supplied from a copper tank and carbon dioxide scrubbed by passing it through a bundle of rope yarn soaked in a solution of caustic potash. During the 1930s and all through World War II, the British, Italians and Germans developed and extensively used oxygen rebreathers to equip the first frogmen. In the U.S. Major Christian J. Lambertsen invented a free-swimming oxygen rebreather. In 1952 he patented a modification of his apparatus, this time named SCUBA, an acronym for "self-contained underwater breathing apparatus," which became the generic English word for autonomous breathing equipment for diving, and later for the activity using the equipment. After World War II, military frogmen continued to use rebreathers since they do not make bubbles which would give away the presence of the divers. The high percentage of oxygen used by these early rebreather systems limited the depth at which they could be used due to the risk of convulsions caused by acute oxygen toxicity.
The following outline is provided as an overview of and topical guide to underwater diving:
The following index is provided as an overview of and topical guide to underwater diving:
