Divers have a choice of several types decompression table options. Two such tables are the Hempleman's and Air Table decompression table. Both tables have both their benefits and drawbacks. These tables should be handled with care. Always use a dive guide in conjunction with the decompression Table.
Air Table decompression tables
Decompression tables were developed in the 1930's by the Navy's Naval Experimental Diving Unit. They created the first standardised tables based upon a theory. This theory said that the human body can remove nitrogen in a linear way, not an exponential manner. To accommodate this theory, decompression tables have been created to help divers stay safe and sound underwater.
Originally, diving practitioners relied on 'per compartment' accounting, which is a more conservative approach to determining nitrogen content. This method compares the various compartment gases to a matrix called M-values. These values are commonly referred to by divers as "half-times", but it is important to remember that they are mathematical expressions and not real entities. These air tables are conservative for short-term dives and can be inaccurate for shallower, longer dives.
Hempleman's decompression table
Val Hempleman's decompression table helped save many lives by keeping the Royal Navy at the cutting edge in deep diving technology. Hempleman's tenure as the Royal Naval Physiological Laboratory Superintendent from 1968 to82 saw him work to overcome "the bends." Hempleman's research on decompression tables allowed a man to survive for ten hours at depths equivalent to 1,535 feet.
Hempleman changed his tables to include a variable ratio for tissue nitrogen tension and ambient press in 1968. He was initially unable get the Navy adopt the new tables but modified them based his diving experience. The Navy adopted the updated tables in 1972.
Hempleman's revised despression tables
Hempleman's 1968 revised decompression table for diving was published. These tables provide a variable ratio in tissue nitrogen tension to ambientpressure. Although the Navy initially did not like these results, Hempleman modified the tables for practical purposes and the new tables were eventually adopted by the Navy in 1972.
In 1908, Haldane published the first table that was based on his model. In 1908, Haldane published the first known diving tables. He was an adventurous self-experimenter. His experimental studies included animal experiments and the first decompression table for the British Admiralty. The clinical endpoint of decompression sickness was widely used by Haldane.
Hempleman's modified Decompression Tables
Hempleman revised decompression charts in 1968 to incorporate a variable ratio for tissue nitrogen tension and ambient press. However, the Navy did not approve of the changes and refused to implement the tables. This led Hempleman to change the tables for practical purposes. These tables were later reproduced in metric units and were adopted by the U.S. Navy in 1972.
The British Royal Navy adopted them in 1908, and they continued to use them until the 1950s. In the same decade, U.S. Navy adopted what are now called C- and R tables. This practice became widespread in the 1980s.