, Decompression Tables
are printed cards or booklets that allow divers to determine for a particular dive profile and breathing
gas, the Decompression stops
required for that dive in order to avoid decompression sickness
With dive tables, it is assumed that the dive profile is a square dive, meaning that the diver descends to maximum depth immediately and stays at the same depth until resurfacing (approximating a rectangular line when drawn in a coordinate system where one axis is depth and the other is duration). Some dive tables also assume physical condition or qualifications of the diver, e.g., Navy dive tables should not be used by recreational divers.
More complex tables can take into account staged dives, dives performed at altitude, and decompression dives.
The knowledge of decompression and decompression sickness developed in the 19th century. The studies used sponge diver experiences as input. The first workable decompression table came available in 1908.
Common Decompression Tables
- the Dive computer - has the advantages of monitoring the actual dive, as opposed to the planned dive, and does not work on a "square profile" - it dynamically calculates the real profile of depth over time.
- bespoke tables generated by decompression software - represent a diver's specific dive plan and breathing gas mixtures.
- Ratio deco is a simplified method for quickly determining the necessary decompression profile without the use of written tables or computers. It is taught in advanced diving courses held by GUE instructors. Ratio Deco relates to using a known set point of decompression obligation related to a specific depth and bottom time. The decompression obligation changes in set increments relative to the set point with changes in actual depth or bottom time.
- Decompression software such as , used to simulate decompression profiles with different gas mixtures.