Slow tissue on gas from stops

[Dan_P]

The two profiles from the video were listed here:
UTD Decompression profile study results published

The total decompression time of RD here is 43min, right? But you say it should've been only 36min including the 6min deep stops. So, you suggest they should've done even less shallow time to get a better picture of UTD RD performance?

The short answer, no - I am not saying the added time was placed shallow, and it wasn't.

36 minutes is right, yes.
But that additional time is not shallow time specific, rather spread out evenly across the segments.
With the deep stop emphasis in RD1.0, it would have been distributed significantly deeper within the 21m-segment, and the deep stops more and deeper, than it/they would be with RD2.0, but that's another matter.

The thing about it is, 6 minutes were added (and not just shallow) for reasons I haven't been able to figure out yet.
But it's well strange.

In either case, it means that we can't use these findings in the fashion attempted above, rather only to support that RD1.0 placed too much emphasis on deep stops, but we don't know exactly by how much. I believe that's rather in equilibrium with what @Dr Simon Mitchell had been saying up until this point.

 

[UWSojourner]

What I am saying, is this:
There is a difference between "arbitrarily adding extra time", and "given a 44% time advantage".

No there is not any difference. Your profile does not know the motivation of why it has the time it does. It simply executes the time provided according to its algorithm, or "strategy" if you prefer.

The dive trials, and several UTD people, clearly represented the test as a UTD-RD profile. That profile had a 44% time advantage over the GF profile tested.

If the RD blueprint states 36 minutes are called for, but the trial imposes doing 42 minutes, you wouldn't call those extra 6 minutes a "bonus", you'd call them a "design flaw".
That's a reasonable concern to have about the trial's design.

That's actually a HUGE concern for me. But not about the trial.

Given a rational decompression method, providing additional time to decompress should always improve the decompression. What you seem to be implying is that if you give UTD-RD additional decompression time it might increase the decompression risk, or actually degrade the decompression??

 

[Dan_P]

No there is not any difference. Your profile does not know the motivation of why it has the time it does. It simply executes the time provided according to its algorithm, or "strategy" if you prefer.

The dive trials, and several UTD people, clearly represented the test as a UTD-RD profile. That profile had a 44% time advantage over the GF profile tested.



That's actually a HUGE concern for me. But not about the trial.

Given a rational decompression method, providing additional time to decompress should always improve the decompression. What you seem to be implying is that if you give UTD-RD additional decompression time it might increase the decompression risk, or actually degrade the decompression??

Yes, I do actually prefer "strategy", thank you.

By your logic, you may as well have made the choice to put it all into deep stops, beause there is some time allocated to deep stops, and more is better. The key word here is choice.

I'd want to strategize on why to add more time, what I'm trying to achieve with it, and where to put it, if and when I do in fact add time to my decompression - you can add time, or remove time, but you need to embrace that you are the one doing it.
You can't just blindly trust some algorithm to do it for you.
That's like wanting an abacus to be a laptop.

And no, I'm not saying I see a basis for arguing that the results would be different if the deco time were shorter.
I'm saying that you're wrong to assume quantification of the degree to which RD1.0 was overemphasising deep stops, on the basis of arbitrarily added decompression time.

 

[UWSojourner]

By your logic, you may as well have made the choice to put it all into deep stops, beause there is some time allocated to deep stops, and more is better.

Not at all. Any rational decompression method should be able to make use of more time to improve the decompression (assuming the diver hasn't completely off gassed). Shoving all the additional time into bottom time, for example, would clearly not be rational since that would harm the decompression.

I'm actually giving UTD-RD the benefit of the doubt in believing the additional time helped it's result. In assuming that I am giving UTD-RD the respect of being a rational decompression method. You seem to be arguing that the additional time was not "an advantage" and are, therefore, not giving UTD-RD that benefit.

And no, I'm not saying I see a basis for arguing that the results would be different if the deco time were shorter.

I hope you would concede that the results were better than they would have been for UTD-RD if it had not been given the time advantage. I don't want to argue your position for you, but not affirming that is a self-inflicted wound, and its fatal.

If you can't say the results were better for UTD-RD due to the extra time, then you're saying that the UTD-RD strategy can't be trusted to improve a decompression if given additional time. And that's a worse result for UTD-RD than simply saying it's inefficient, even if it's 44+% inefficient (in this study).

 

[Jack Hammer]

The UTD RD profile was presented by the inventor of UTD RD and performed by representatives of the official agency promoting it, UTD. Upon finding out the comparative results of the study UTD made changes their RD procedures.

In my book, and I believe to most others, that reads as the profile as performed was a "proper" and official UTD RD profile.

 

[Dan_P]

Not at all. Any rational decompression method should be able to make use of more time to improve the decompression (assuming the diver hasn't completely off gassed). Shoving all the additional time into bottom time, for example, would clearly not be rational since that would harm the decompression.

I'm actually giving UTD-RD the benefit of the doubt in believing the additional time helped it's result. In assuming that I am giving UTD-RD the respect of being a rational decompression method. You seem to be arguing that the additional time was not "an advantage" and are, therefore, not giving UTD-RD that benefit.

I hope you would concede that the results were better than they would have been for UTD-RD if it had not been given the time advantage. I don't want to argue your position for you, but not affirming that is a self-inflicted wound, and its fatal.

If you can't say the results were better for UTD-RD due to the extra time, then you're saying that the UTD-RD strategy can't be trusted to improve a decompression if given additional time. And that's a worse result for UTD-RD than simply saying it's inefficient, even if it's 44+% inefficient (in this study).

You're still wanting an abacus to be a laptop.
If you're adding more time arbitrarily, then you are deciding to do so, and you decide where it goes.

Besides, like I've said, neither you or I have basis for making slight-of-hand statements about whether, if and/or how the arbitrarily added time impacted the results, regardless of any and all if-then relationships conjured.

Now - what I'm saying is you can't quantify a degree to which RD1.0 was overemphasising deep stops, on the basis of what you've presented. Obviously.

 

[Dan_P]

The UTD RD profile was presented by the inventor of UTD RD (it's just "inventor of RD", I believe) and performed by representatives of the official agency promoting it, UTD. Upon finding out the comparative results of the study UTD made changes their RD procedures.

In my book, and I believe to most others, that reads as the profile as performed was a "proper" and official UTD RD profile.

I honestly don't know why the dive parametres were engineered as they were, but you're more than welcome to look at them, run the math and see for yourself.
The parameters are not in accordance with standard procedure, and I think it's unlikely that divers had anywhere near a carte blanche to do their deco on the fly, in a scientific study.

I don't know why the deco time was made so long for the rd-sample, but it's not the deco time you'll get if you run it "per protocol".

 

[UWSojourner]

Now - what I'm saying is you can't quantify a degree to which RD1.0 was overemphasising deep stops, on the basis of what you've presented. Obviously.

It's only "obvious" if you close your eyes to the information provided in the study, OR you assume UTD-RD harms profiles if provided with additional time. You actually seem comfortable doing both.

But assuming UTD-RD is a rational decompression strategy/method that can make positive use of time if provided with it, the UTD-RD vs.GF study demonstrated a pretty benign profile where UTD-RD was at least 44% inefficient compared to the GF profile it was compared to. That inefficiency statistic derives from the FACT that the UTD-RD profile had 44% more decompression time, but still saw inferior results compared to the time-disadvantaged GF profile.

 

[Dan_P]

It's only "obvious" if you close your eyes to the information provided in the study, OR you assume UTD-RD harms profiles if provided with additional time. You actually seem comfortable doing both.

But assuming UTD-RD is a rational decompression strategy/method that can make positive use of time if provided with it, the UTD-RD vs.GF study demonstrated a pretty benign profile where UTD-RD was at least 44% inefficient compared to the GF profile it was compared to. That inefficiency statistic derives from the FACT that the UTD-RD profile had 44% more decompression time, but still saw inferior results compared to the time-disadvantaged GF profile.

That's a gargantuan oversimplification, and you're working on assumptions that have zero backing in the study you reference, nor in any documentation relating to ratio deco, all while forcing Ratio Deco (abacus/square peg) into being an algorithm (laptop/round hole).

What I'm saying is, you don't have the references to carry your statement that the Spisni study findings means RD1.0 deep stop overemphasis rate is quantifiable by these crude logics, nor can you assume that the relationship across deco time added and results, is linear.

 

[UWSojourner]

That's a gargantuan oversimplification, and you're working on assumptions that have zero backing in the study you reference, nor in any documentation relating to ratio deco, all while forcing Ratio Deco (abacus/square peg) into being an algorithm (laptop/round hole).

What I'm saying is, you don't have the references to carry your statement that the Spisni study findings means RD1.0 deep stop overemphasis rate is quantifiable by these crude logics, nor can you assume that the relationship across deco time added and results, is linear.

I understand.

And completely disagree. The study provided more information than you're willing to accept.