limeyx:
BUt doesnt that assume that Decoplanner, GAP etc are somehow the "Gold standard" and always correct? How do we know they are accurate? Well, by diving and seeing what happens.
First of all, look at the sentence above the one you chose to quote:
charlie99:
If you have reasonable faith in the model, then the first round of validation of a proposed deco tracking method is to run various profiles through it, and also through an underlying decompression model in which you already have reasonble faith because of prior experiments.
In other words, running a proposed tracking method through the various models to see if that method is consistent with them is the first, easiest, and quickest thing to do. It isn't the
only validation.
If you are actually trying to develop a new understanding of decompression and develop a new model, that is quite different than validating the safety of a particular method of calculation decompression or tracking time and depth. Using those models/deco programs to check a proposed method of tracking saves a lot of time and effort. It weeds out the obviously bogus methods. It gives some pretty good indications of where the methods apply and where they fail.
Average depth tracking isn't a deco model. It is a tracking algorithm. Square profile tables are not deco models. They are tracking method or algorithm. Do you really think all of those many numbers on the dive tables have been tested? Of course not. What gets tested is the underlying model. Are they perfect. Obviously not. But the underlying models are a lot closer to the "truth" than is an imperfect, simplified representation such as a square profile table (PADI RDP, USN Table, etc.) or a simplied tracking method such as "average depth diving".
Do you really think that if suddenly a large number of people got bent on a particular Decoplanner profile they wouldn't tweak the numbers?
Of course numbers will be tweaked, but once it is verified that the program is running correctly, what will be tweaked is model, not some random number or limit in the program. Indeed, a signficant number of people being bent following Decoplanner profiles would probably result in several models being tweaked, not just the Buhlmann model used in Decoplanner 1 and 2.
And amusingly a lot of the data for ratio deco essentially does come from those packages in the first place. It's just been "massaged" somewhat
Not amusing at all. Obvious and natural, if one thinks about it a bit.
What would be amusing would be someone thinking that how one tracks time and depth somehow affects the biophysics of decompression.
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I think a lot of the heat and confusion around the issue of average depth diving is due to confusing this method of tracking decompression status with a decompression model. That confusion isn't very surprising, considering how many people continue to think that tables are deco models, when in reality they are relatively limited, poor representations of the model, particularly for multilevel dives.
Average depth diving has the advantage of factoring in depths other than just the maximum depth, as is done on a square profile table.
). But there IS a model, and calculation which is done. I just felt limey's comments suggested that the tables were derived by diving a lot of people and seeing which profiles produced DCS and which didn't. There IS more structure to it than that.
