Dive Computers – Insights for Divers & Professionals. Wolfgang Wild

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      Without going too deep into that (thanks to the free download possibility everything can be studied in detail today) only a few more aspects in bullet point form which might be of most interest for the reader of this eBook:

      • As the development of the mathematical equation had been financially sponsored by PADI (Professional Association of Diving Instructors), they had secured the exclusive rights for PADI to develop and distribute a new dive planner for recreational divers based on the DSAT findings; so, in 1988 the Recreational Dive Planner (RDP) was launched. With the RDP divers had for the first time a dive table which does not penalize the recreational diver with too short no-decompression times and limits. Just to remember: the until then traditionally used US Navy tables had never been thought for recreational diving (and for female divers not at all). Some other dive tables reacted on the RDP by shortening their (somehow created) no-decompression limits to increase their safety margin.

      • Later, DAN and PADI subjected the RDP to further testing: 4 (four) dives daily during 6 (six) consecutive days; these dives were conducted in the controlled environment of a hyperbaric chamber, i.e. dry dives; after each dive the 20 divers were evaluated for bubbles by the use of Doppler ultrasound. Result after 475 dives: „No decompression sickness and minimal detectable bubbles.“ (Richardson, Drew, How Much Diving Is Too Much?, The Undersea Journal, Second Quarter 1990, p. 14)

      • Because DSAT had released the algorithm for free use (except for the production of dive tables), several smart diving equipment manufacturers seized the chance, ordered together the production of a chip resp. microprocessor and had it installed in their newly developed dive computers; this was truly smart because they saved a lot of development costs. As far as the author of this eBook is informed, in the USA these manufacturers were Dacor, Oceanic, Sherwood, and US Divers (even though not all dive computer models of these companies were equipped with the DSAT algorithm). In this way they had a dive computer which was calculating both saturation and desaturation with an extensively validated mathematical equation.

      • In the RDP 14 theoretical tissues or “compartments” are used: 5 – 10 – 20 – 30 – 40 – 60 – 80 – 100 – 120 – 160 – 200 – 240 – 360 and 480 minutes (the term “compartment” will be discussed later). As “controlling tissue” for the RDP finally the 60-minutes compartment was selected. A few points to the concept of a controlling tissue which are probably known by diving professionals and may therefore be skipped by them. All dive tables and dive computers which are based on a so-called “tissue-model” (see further below) use a specific controlling tissue which is defined as follows: this is the theoretical tissue, which came closest to its maximum but still safe gas-loading during a dive. The criterion for this closest margin meant for the development of the Recreational Dive Planner (RDP), as already shortly mentioned <no Doppler Grade as defined by Dr. Merrill Spencer above Grade 3> or, in other words, no Doppler audible bubbles which could have lead to DCS symptoms. Result for utilizing this concept in the development and validation of the RDP: “No cases of decompression sickness occurred in any test.” (DSAT, Recreational Dive Planning … The Next Generation – New Frontiers in Hyperbaric Research, 1987, Executive Summary, p. 4)

      • As said, the controlling tissue of the RDP is the 60-minute compartment, while for the original US Navy tables it’s the 120-minute compartment. For military divers with their given dive objectives and profiles a 120-minute compartment may be quite adequate, for recreational diving it is unnecessary conservative. The calculated (still safe) saturation level of this controlling tissue is further used for planning the maximum safe dive time for a repetitive dive which divers know to have shorter no-decompression times than the previous dive. Just so much at this point on that topic, later in this eBook a bit more. One additional hint regarding the number of compartments which are used in the algorithm of the RDP. For planning dives on sea level and to a maximum altitude of 300 meters/1.000 feet the RDP is based on above presented 14 compartments; for altitudes above 300 meters/1.000 feet as many as 20 compartments were used to calculate the RDP altitude conversion. (See Richardson, Drew, Deep, Repetitive Diving – A New Rule Applies, The Undersea Journal, Third Quarter 1989, p. 26)

      • Following the RDP “Wheel” and RDP table launch in 1988, further dive tables were introduced for using the RDP not only with air but also with Enriched Air / Nitrox: the EANx32 and EANx36 RDPs, released in 1996; and years later also “electronic” dive tables followed: the eRDP (2005) und the eRDPML (2008). The eRDPML uses the validated data of the RDP in its original “Wheel“ version, so that even multilevel dives for up to three levels can be calculated as no-stop dives. [Note: This dive planner is no dive computer and can not be taken under water.]