US Navy decompression models and tables

The US Navy has used several decompression models from which their published decompression tables and authorized diving computer algorithms have been derived. The original tables were based on the work of J.S.Haldane in England in the early 20th century, later they were modified by Robert D. Workman to incorporate M-values, and later again a significantly different model, the VVal18 exponential/linear model was developed by Edward D. Thalmann. Besides the air and heliox tables for open circuit bounce dives, the US Navy has published a variety of hyperbaric treatment tables, Tables for open and closed circuit Nitrox and Trimix, A system for modifying tables for use at high altitudes, and saturation tables for various breathing gas mixtures. Many of these tables have been tested on human subjects, frequently with an end result of symptomatic decompression sickness, and for this reason their test results are considered some of the most reliable available. US Navy tables have generally been freely available for use by the general public, and have often been modified to further reduce risk, as commercial and recreational divers do not always fit the physical requirements for military divers, may not have a recompression chamber on site to manage decompression sickness on those occasions when it does occur, and may prefer to operate at a lower risk than military personnel. Several recreational diving tables were originally based on US Navy diving table.