page_title: History of scuba diving
section_title: Dive computers
hierarchical_section_title: History of scuba diving / Post WWII / Dive computers
caption_attribution_description: English: Shearwater Perdix and Ratio iX3M GPS dive computers in compass mode
context_page_description: The history of scuba diving is closely linked with the history of scuba 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.
context_section_description: Scuba decompression planning originally based on printed decompression tables developed for surface supplied air diving. This was inefficient for multi-level dives, and the custom of multilevel diving using tables was not supported by formal experimental testing, but seemed to work reasonably well in practice in accordance with the theoretical models.
  The Office of Naval Research funded a project with the Scripps Institute of Oceanography for the theoretical design of a prototype decompression analog computer. The Foxboro Decomputer, Mark I was manufactured by the Foxboro Company and evaluated by the US Navy Experimental Diving Unit in 1957. It was not successful.
  The first recreational mechanical analogue dive computer, the "decompression meter" was designed by the Italians De Sanctis & Alinari in 1959 and built in their factory named SOS, which also made depth gauges. The device functioned so poorly that it was eventually nicknamed "bendomatic". In 1965, Stubbs and Kidd applied their decompression model to a pneumatic analogue decompression computer. Several analogue decompression meters were subsequently made, some with several bladders for illustrating the effect on various body tissues, but they were sidelined with the arrival on the scene of electronic computers.
  In 1983, the Hans Hass-DecoBrain, designed by Divetronic AG a Swiss start-up, became the first digital electronic diving computer, capable of displaying the information that became the industry basic standard. The DecoBrain was based on A. Bühlmann's 16 compartment (ZHL-12) tissue model In 1984 development of the US Navy diving computer which was based on a 9 tissue mixed gas model used for the US Navy tables for the MK-15 rebreather was completed by Divetronic AG by adapting the Deco Brain under an R&D contract.
  The 1984 Orca EDGE was produced. The EDGE displayed the ceiling or the so-called "safe-ascent-depth". A drawback was that divers faced by a ceiling did not know how long they would have to decompress, but the display featuring the saturation level of 12 tissue bars permitted experienced users to make a reasonable estimate of their decompression obligation. Orca Industries continued to refine their technology with the release of the Skinny-dipper in 1987 to do calculations for repetitive diving. They later released the Delphi computer in 1989 that included calculations for diving at altitude as well as profile recording.
  Even by the late 1980s, dive computers were not widely accepted. There was a general mistrust of relying on electronics that your life might depend upon underwater, and objections ranging from dive resorts felt that the increased bottom time would upset their schedules, to that some divers felt that the increased bottom time would esult in many more cases of decompression sickness. A workshop held under the auspices of the American Academy of Underwater Sciences brought together a diverse group that included most of the dive computer designers and manufacturers, some of the best known hyperbaric medicine theorists and practitioners, representatives from the recreational diving agencies, the cave diving community and the scientific diving community." This workshop produced a set of consensus recommendations for the design and safe use of dive computers that was generally accepted by the scuba diving community, and consequently the opposition to dive computers dissipated, numerous new models were introduced, the technology dramatically improved and dive computers became the standard scuba diving decompression monitoring equipment.
  In 2001, the US Navy approved the use of Cochran NAVY decompression computer with the VVAL 18 Thalmann algorithm for Special Warfare operations.
  In 2008, the Underwater Digital Interface (UDI) was released to the market. This dive computer, based on the RGBM model, includes an underwater communication system that enables divers to transmit text messages, also featuring SOS and homing capabilities, and digital 3D compass.
  Training agencies have introduced the use of dive computers as part of standard trainin
caption: Shearwater Perdix and Ratio iX3M GPS dive computers in compass mode
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