Highwing, what exactly is VooDoo about this concept? I consider myself an "educated diver" and can see the reasoning and think there could be some value in this.
Thank you for asking. My opinions are based on endlessly studying this general topic, and a few live human experiments I've accidentally and/or purposefully performed on myself.
Let's agree there are several reasonably validated decompression models available. We potentially agree evidence suggests all the models are essentially flawed in some way. Despite the knowledge the available models are in some ways flawed, the available models are producing the desired result the vast majority of the time. The obvious question becomes, “Is there a missing factor to DCS”, but the equally important question becomes its antithesis.
The principle models, ZHL16B/C+GF, RGBM, VPM, etc. are essentially available for study. I can compare them, I can evaluate the differences in pre-planning, I can complete the dive and evaluate the parameters and the outcome they produced. I can use the data I’ve collected about my dives, and myself and make purposeful manipulations and track and evaluate that data/result. With proprietary and secret company models, and extraneous inputs, I lose almost all that advantage as the proprietary secret models hide what they’re doing.
Some dive computers are preset with the conservatism at ZHL16-C 30/70GF which would be widely regarded in practical application by a recreational diver as excessively conservative. Because my latest computer came equipped accordingly, I dove the computer this way for a while. Having been previously diving 30/85, it was clear I was staying shallow longer and I actually could feel the difference occasionally. What I eventually determined was that I felt more awake and less drained when I dove 30/70 on deeper, and perhaps technical dives. This caused me a bit of pause, did my body really respond differently staying shallow longer? So I bought my wife the same computer and we dove, and unprompted she noted she was not as tired.
It was at this moment I realized we are absolutely benefiting by exiting the water at 70% of the M-Value versus 85% of the M-Value. In my next experiment, I set the conservatism to 30/85% and we dove single-gas recreational limits using air. Post dive analysis, we both felt good, and no problems or fatigue. After a good ponder, I realized that more knowledge of the model allows me to manipulate it in a meaningful way for my particular application. My body responds just fine being a little more aggressive on recreational dives, but deeper multi-gas dives, it doesn’t. I discovered my ending result is more physically tolerable spending more time in shallow water decompressing on the bigger dives.
I don’t appreciate proprietary models which are not released to the diver for evaluation and consideration. I want to see where the starting point is and what I’m actually manipulating to assure that I’m moving the model in a meaningful way in the direction of intent. Say I set the body size to fat-dude, is it adding a deep stop, or adding shallow time? If I learn that the fat-dude setting is adding deep time and I know my body is responding better to longer shallow, do I adjust it to skinny-dude if I'm really a fat-dude?? Conservatism is nothing more than a model correction in an attempt to push the over-pressure gradient down. The question becomes, why manipulate a model from somewhere to somewhere when you don’t have a clue where you started? However, if evidence is presented that conclusively tied biofeedback with touch-based sensors to inert gas loading and test proved the new technology provided a meaningful risk reduction I’d consider it. If you look at the likelihood of DCS incidence per dive attempt, you’re going to find it very difficult to move that needle in a statistically meaningful way at this juncture.
