Underwater Habitat
Underwater Habitat, a chamber on the seabed in which divers can live for a brief or extended period. The pressure of the atmosphere inside the chamber is equal to the pressure of the water outside. The pressurized environment makes it unnecessary for the divers to decompress between excursions into the water. This system of sustained pressurization is known as saturation diving.
The seabed dwellers are known as aquanauts or oceanauts. Their activities consist typically of scientific research, the servicing of offshore oil wells, and the study and raising of fish and other marine life. There are military applications, also, such as installing and tending seabed sonar systems for detecting submarines.
Habitats are supplied from the surface with electric power, telephone lines, and, generally, a pressurized mixture of gases for breathing. Life in the habitat is usually monitored above on closed-circuit television. Supplies are lowered from the surface. At relatively shallow depths, the breathing mixture consists of oxygen and nitrogen; at greater depths, this mixture produces harmful physiological effects and a breathing mixture consisting largely of helium is used. With helium, however, the aquanauts can suffer from cold, because helium carries off body heat so quickly, and from communication problems, because helium distorts the voice.
The doorway to a habitat is a hatch on its underside. Because the chamber is pressurized, water does not enter through the hatch when it is open. To go into the water, the divers wear scuba gear and wet suits or some variation on scuba outfits. If they are breathing helium, it is usually fed to them by hose from the habitat. In deep water, because of the penetrating cold, the suits have special insulation or are warmed electrically or by hot water circulated from the habitat.
HistoryThe principle of saturation diving was proposed by Captain George F. Bond, a U.S. Navy physician, in 1957. Working in close communication with Bond and each other, American inventor Edwin A. Link and French oceanographer Jacques Cousteau developed projects based on the principle. In 1962 both launched experiments in pressurized underwater sojourns. Link, calling his project Man-in-the-Sea, lowered a diver in a tethered capsule to 200 feet (61 m) for 24 hours. Cousteau placed Conshelf I, a free-standing structure, at a depth of 36 feet (11 m) and had two divers live in it for a week. In both experiments the divers spent considerable time in the water.
Cousteau's Conshelf II (1963), also at 36 feet, was a cluster of structures that accommodated five men for a month and provided a hangar for Diving Saucer—the first facility for operating a submersible entirely from a submerged base. For one week of the month, two divers stayed in a separate habitat at 90 feet (27 m). Conshelf III (1965) was at a depth of 328 feet (100 m) and was notable for having its own compressor for pressurizing the atmosphere.
Meanwhile, in 1964 Link had established his second chamber, an inflated rubber habitat called SPID, at 432 feet (132 m). Link also designed a small inflatable working chamber called Igloo. Both were tested repeatedly over several years.
The U.S. Navy adopted the Man-in-the-Sea project, under the direction of Captain Bond, and began its Sealab program in 1964. Sealab II (1965) initiated the use of a trained dolphin for running errands. Sealab III (1968), an elaborate project at a depth of 600 feet (183 m), was discontinued after the death of a diver. The Navy thereafter adopted an alternate system of saturation diving in which, for the duration of a work project, divers live in their pressurized decompression chamber on the surface and are carried to their working site in a tethered pressurized capsule.
The Tektite program, 1969–70, was sponsored by a group of United States governmental agencies and private institutions. Twelve scientific teams spent from 20 to 60 days each underwater off the island of St. John in the U.S. Virgin Islands. During 1971–75 the National Oceanic and Atmospheric Administration (NOAA) sponsored a program off Great Bahama Island with the underwater habitat Hydrolab. The program continued during 1977–85 with Hydrolab stationed off St. Croix in the U.S. Virgin Islands. NOAA established a larger underwater habitat called Aquarius off St. Croix in 1987.
Various other nations have had underwater habitat programs. The West German Helgoland project (1969) was notable for being located in the icy waters of the North Sea. Diving clubs have constructed seabed chambers, also; part of the appeal is the serene isolation the chamber provides.