title: Decompression management by 43 models of dive computer: single square-wave exposures to between 15 and 50 metres' depth.
abstract: BACKGROUND
  Dive computers are used in some occupational diving sectors to manage decompression but there is little independent assessment of their performance. A significant proportion of occupational diving operations employ single square-wave pressure exposures in support of their work.
  
  
  METHODS
  Single examples of 43 models of dive computer were compressed to five simulated depths between 15 and 50 metres' sea water (msw) and maintained at those depths until they had registered over 30 minutes of decompression. At each depth, and for each model, downloaded data were used to collate the times at which the unit was still registering "no decompression" and the times at which various levels of decompression were indicated or exceeded. Each depth profile was replicated three times for most models.
  
  
  RESULTS
  Decompression isopleths for no-stop dives indicated that computers tended to be more conservative than standard decompression tables at depths shallower than 30 msw but less conservative between 30-50 msw. For dives requiring decompression, computers were predominantly more conservative than tables across the whole depth range tested. There was considerable variation between models in the times permitted at all of the depth/decompression combinations.
  
  
  CONCLUSIONS
  The present study would support the use of some dive computers for controlling single, square-wave diving by some occupational sectors. The choice of which makes and models to use would have to consider their specific dive management characteristics which may additionally be affected by the intended operational depth and whether staged decompression was permitted.
authors.affiliation: UK National Facility for Scientific Diving Scottish Association for Marine Science, Dunstaffnage Marine Laboratories, Dunbeg, Oban, Argyll PA37 1QA, Scotland, Phone: +44-(0)1631-559236, E-mail: mdjs@sams.ac.uk.
authors.forename: Martin D J
authors.initials: MD
authors.lastname: Sayer
authors.affiliation: UK National Facility for Scientific Diving hosted at the Scottish Association for Marine Science Laboratories near Oban, Argyll, Scotland.
authors.forename: Elaine
authors.initials: E
authors.lastname: Azzopardi
authors.affiliation: Chalmers University of Technology, Gothenburg, Sweden, and SeaBear Diving Technology, Austria.
authors.forename: Arne
authors.initials: A
authors.lastname: Sieber
mesh_terms: D000465:Algorithms; D003664:Decompression / Q000295:instrumentation*; D004242:Diving / Q000502:physiology*; D008905:Minicomputers / Q000145:classification; D012016:Reference Values; D015203:Reproducibility of Results; D012623:Seawater; D012984:Software; D013696:Temperature; D013997:Time Factors
keywords: Computers – diving; decompression; decompression tables; dive profile; occupational diving