Bühlmann decompression algorithm: Difference between revisions

Revision as of 20:12, 20 August 2023

Revision as of 20:16, 20 August 2023

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==Gradient factors (GF)==

User input of [[gradient factor]]s is sometimes available for planning and real -time applications.

Gradient factors are a calculation trick (Erik C. Baker) that consists of taking a percentage of each M-Value (e.g. 90%) in order to increase conservatism (shorter duration without mandatory stops, longer and/or deeper stops) by reducing the maximum amount of neutral (inert) gas (e.g. nitrogen) accepted when approaching surface (Maximum Value of each tissue compartment at... 9 m, 6 m, 3 m, surface).<ref name="Foret-1" />.

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For dives without mandatory stops, only GFhigh is used, even if a GFlow is defined.

Twin GFs (e.g. 80/80) have the same effect thanas artificially increasing dive time (the time taken into account is greater than the actual time). When using printed dive tables, it is like an "impromptu addition of extra increments of depth and time beyond those actually required by the dive, universally known as ''Jesus-factoring''".<ref name="Shields" />

Asymmetric GFs (e.g. 30/70) can be used to force deep stops (e.g. Heliox or Trimix dives when the algorithm used is not conservative enough). Deep stops can be defined as follows: “one or more voluntary or empirically derived decompression stops that are deeper than any prescribed by the algorithm utilized”.<ref name="Deep-Stops" />

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* leaving GFlow and GFhigh free for input;

* by including in the algorithm a modification of the GFs according to the diver's behaviorbehaviour (profile, ascent speed, etc.).

In all cases, the choice of GF values is arbitrary.