The study referred to in this string - published in the March 2017 issue of DHMJ - looks like it took place in early 2014. Since then, UTD revised RD and released Ratio Deco version 2.0 in mid 2016 - which places less emphasis on deep stops ...
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I personally think that the word "compartment" is deceptive because tissues are not necessarily compartmentalized.
Hi @sigxbillThe study referred to in this string - published in the March 2017 issue of DHMJ - looks like it took place in early 2014. Since then, UTD revised RD and released Ratio Deco version 2.0 in mid 2016 - which places less emphasis on deep stops ...
So here is the deal. Computers algorithms - like Sheerwater Perdix, can be adjusted with gradient factors depending on your own personal preference. Likewise, Ratio Deco 2.0 can be shaped depending on your own personal preference. Below is a comparison of two ascents used during the study, and an example of an ascent I calculated using RD 2.0. Please note that I could have shaped my 21-9m stops to look like the RD stops used in the study - but I chose not to - and as far as I know - my shape would also be correct. Also note that the main difference between RD 1 and 2.0 *in this profile* is that 2.0 eliminates the 36m and 33m stops.
Also notice that the main difference between my RD 2.0 profile and the Buhlmann is that mine spends only 5 extra minutes total spread between the 21-18 meter stops - right after switching to ean50.
Disclaimer: I am not a UTD Technical Instructor, and this table contains a possible UTD RD 2.0 tec 2 profile. It is provided as an example only, so do not rely on it for your own personal dive without first studying RD, taking a UTD RD class, and accepting the risk for yourself.
Do you mind providing the bottom time, bottom depth, and deco gasses for the profile you created? I tried replicating it with 30/85 and couldn't quite find it. Closest I got was 200ft for 15min with O2 and EAN50.
The ratio deco strategy did not confer any benefit in terms of bubbles but showed the disadvantage of increased decompression-associated secretion of inflammatory chemokines involved in the development of vascular damage.
According to the summary at the link that @Dan_P posted.
The study was 50m for 25:00, using "trimix", 50% and O2, with GF30/85. The summary does not say exactly what blend of trimix they used. When I put the dive parameters through the Subsurface planner, assuming 18/45 for the bottom gas, the result has a first stop at 24m, and a total deco time of 33:00 (i.e. total run time of 58:00), compared to @sigxbill's first stop of 27m and deco time of 30:00.
RD 2.0 may be "new and improved" from RD 1.0, but then, based on recent research, I would use GF50/80 for the Buhlmann option. So, how would those compare? I would bet a dollar that GF50/80 would still produce a shorter runtime AND less "increased secretion of inflammatory chemokines". Only a dollar, though. ;-)