Slow tissue on gas from stops

[Jack Hammer]

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".

It looks about spot on to how I recall my RD training about 10 years ago. I could be rusty though, as I use different methods to plan dives. I learned in "standard" not metric.

50m/165' round to 170', 1:1 BT + 5 mins for each 10' makes 35 mins deco time. Deco time to be distributed between 3m/20' & 21m/70', an additional first stop at 80% max depth (use 75% for easy math) then 1 minute (30 sec pause, 30 sec travel) every 3m/10' to first deco stop at 21m/70'. Deco time begins at 21m/70'. 35 mins deco, half (round to 18 mins each) spread between stops from 21m/70' - 9m/30 and the other half at 6m/20' (3m/10' optional).

That's pretty much exactly what I see on the listed profile.

For transparency, my training was not with UTD.

 

[Dan_P]

It looks about spot on to how I recall my RD training about 10 years ago. I could be rusty though, as I use different methods to plan dives. I learned in "standard" not metric.

50m/165' round to 170', 1:1 BT + 5 mins for each 10' makes 35 mins deco time. Deco time to be distributed between 3m/20' & 21m/70', an additional first stop at 80% max depth (use 75% for easy math) then 1 minute (30 sec pause, 30 sec travel) every 3m/10' to first deco stop at 21m/70'. Deco time begins at 21m/70'. 35 mins deco, half (round to 18 mins each) spread between stops from 21m/70' - 9m/30 and the other half at 6m/20' (3m/10' optional).

That's pretty much exactly what I see on the listed profile.

For transparency, my training was not with UTD.

Hi Jeff,

Pretty damn close for a 10th year comeback!

The bottom time was 25 minutes, though, so the +5 minutes is right, but the total is 30 minutes, not 35.

Half up, half down (15/15).

That's what I don't get, there was only 25 minutes bottom time.

 

[Dan_P]

I understand.

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

Ditto - but I've just got to say I don't really have a buy-in on how much RD1.0 was overemphasising deep stops by; nor any specific preference on a general deep stop emphasis level that I feel particularly partial towards, either.

 

[Dr Simon Mitchell]

Dan,

You can't say that we have to assume AG got the trial design how he wanted it.

Do you HONESTLY think we would not have heard about it by now if Andrew was not happy with the trial design.

quite frankly, starting to look like a poor attempt of deflecting attention from the fact that you've only just practically approved of UWSojourner's wrongful interpretation of the Spisni trial's findings

UWSojourners interpretation is completely correct, and "quite frankly" this business of admitting that RD over-emphasised deep stops but then advancing multiple arguments suggesting we should not pay much attention to the study is becoming increasingly bizarre.

Your latest strategy of claiming that the RD study profile had 6 minutes of "arbitrarily added" decompression time and your implication that this may have disadvantaged the RD outcome is extraordinary. If a group of the world's experts in applying this algorithm (including the inventor) added (or at least enthusiastically accepted) 6 minutes of decompression time and managed to make the outcome worse what does this say about the algorithm?

Simon M

 

[Dan_P]

Dan,



Do you HONESTLY think we would not have heard about it by now if Andrew was not happy with the trial design.



UWSojourners interpretation is completely correct, and "quite frankly" this business of admitting that RD over-emphasised deep stops but then advancing multiple arguments suggesting we should not pay much attention to the study is becoming increasingly bizarre.

Your latest strategy of claiming that the RD study profile had 6 minutes of "arbitrarily added" decompression time and your implication that this may have disadvantaged the RD outcome is extraordinary. If a group of the world's experts in applying this algorithm (including the inventor) added (or at least enthusiastically accepted) 6 minutes of decompression time and managed to make the outcome worse what does this say about the algorithm?

Simon M

Simon,

I hear what you're saying, yet, for a dive of 25 minutes to avg. 48m, the RD framework subscribes 30 minutes of decompression plus 6 minutes deep stops, total 36 minutes.
That's not what was carried out in the trial dives, and we can speculate all day why, but the simple fact of the matter is that it's not what RD said "by the letter".

I don't think it'll have impacted the learnings from the results, or the takeaway that RD1.0 overemphasised deep stops, but I fail to see how it does not mean that the "bonus minutes" were in fact arbitrary - what I'm saying is we can't then say something to the effect of it got 44% more time, so RD must be 44% less effective; not that I believe it skewed the results in any significant way.
I don't think it's reasonable to just assume a qualitative linearity beyond a certain chronological point in a stop (sequence).

And I've not said or implied that we shouldn't pay attention to the trial, at all.

 

[Diver0001]

You know....

If I zoom WAY out on this discussion and pick the one most relevant aspect of the debate then I have to go back to the foundations of DIR.

DIR was developed specifically to be a statement of best practices -- Indeed within a limited context -- but it started life as the first and only clear statement of best practices we had. From the very beginning it was also a cult of personality but fortunately for the diving community the DIR heavy weights were also exceptionally skilled divers (and sadly, exceedingly poor communicators, but we've mostly put that behind us now).

The problem with DIR is this. It became a cook book. The divers who developed it were very much interested in best practices but the (less experienced) divers who adopted the system were much more interested in conforming to expectations.

Enter RD. RD was initially developed because the dive computers we had at the time were... well ... ****. Even up to about 2005 or so most of the technical computers on the market were unreliable crap. A solution -- a best practice -- was necessary to compensate for the need for flexibility. RD had its hayday between ... let's say ... 1995 and 2005 because it was the best practice.

Since 2005 there have been several very good computers developed. I don't think I need to name them but we all know what I'm talking about. Since 2007 or so we've also had a very fruitful discussion about deco algorithms for technical diving and with respect to ascent protocols new "best practices" have been emerging.

And THERE is the disconnect. Where DIR started life as away to encapsulate best practices it became engraved in stone by those who do not understand it. The early DIR heavy weights are now out of the scene and the flexibility to incorporate best practices has completely disappeared. All that is left is an out of date cook book.

If the DIR founders were still active then we would have abandoned RD years ago and adopted the computer. The computer is better. Even the study that stacked the deck in favour of RD and self proclaimed its intention to prove that RD was superior proved that the computer is superior. This SHOULD be adopted as the best practice but because DIR is a cult of personality AG's opinion is leading for a lot of DIR divers and I see people -- good and intelligent people -- like Daniel defending a bad practice instead of adopting a new best practice. This is, frankly, incredibly sad.

The way I see it, AG is WAY behind the best practice curve at this point and is severely paradigm locked. A paradigm shift is necessary within the DIR community but who will stand up and take the challenge?

R..

 

[UWSojourner]

I don't think it'll have impacted the learnings from the results, or the takeaway that RD1.0 overemphasised deep stops, but I fail to see how it does not mean that the "bonus minutes" were in fact arbitrary - what I'm saying is we can't then say something to the effect of it got 44% more time, so it's 44% less effective; not that I believe it skewed the results in any significant way.

So all the descriptions of the UTD-RD profile here and here by AG and Ben Bos were really just misguided? I guess we'd just need to conclude that AG and Ben Bos are not sufficiently 'Thinking Divers' to know how to adapt a bit more deco time into UTD-RD profiles. You're throwing a lot of people under the bus in order to attempt to deflect responsibility from UTD-RD itself.

But ok. I guess what we can all agree on, then, is that "the tested profile that was labeled UTD-RD in those videos" did get 44% more time and still had inferior results to the GF30/85 profile that was also tested. And therefore "the tested profile that was labeled UTD-RD in those videos" is at least 44% inefficient for the dive tested. That is, despite the 44% time advantage, "the tested profile that was labeled UTD-RD in those videos" produced decompression stresses not observed in the time disadvantaged GF30/85 profile.

 

[Dan_P]

So all the descriptions of the UTD-RD profile here and here by AG and Ben Bos were really just misguided? I guess we'd just need to conclude that AG and Ben Bos are not sufficiently 'Thinking Divers' to know how to adapt a bit more deco time into UTD-RD profiles. You're throwing a lot of people under the bus in order to attempt to deflect responsibility from UTD-RD itself.

No, I'm not throwing them under the bus, that's a serious digression from and misrepresantation of what I've said and its meaning or implications.

I'm saying the trial design attributed more time to the RD sample, and looking at RD framework, I don't know why. And I'm saying it has a significance for what we might say about the degree to which RD1.0 overemphasised deep stops, not that that's clear anyway.
That's it.

But ok. I guess what we can all agree on, then, is that "the tested profile that was labeled UTD-RD in those videos" did get 44% more time and still had inferior results to the GF30/85 profile that was also tested. And therefore "the tested profile that was labeled UTD-RD in those videos" is at least 44% inefficient for the dive tested. That is, despite the 44% time advantage, "the tested profile that was labeled UTD-RD in those videos" produced decompression stresses not observed in the time disadvantaged GF30/85 profile.

Yes, absolutely, fair enough. I don't have a problem with that, it's just asterisks and footnotes from there.
Such as, we can't assume a qualitative linearity in the stops distributed, or, we should wish to see the results of doing a GF30/85 with the same runtime to confirm that this didn't produce any negative change also, or, the above is not the same as inverting the statement to mean that because of the arbitrary addition of time, RD must be 44% less effective than GF30/85.

Footnotes that have significant enough implications, I think.

 

[Dan_P]

You know....

If I zoom WAY out on this discussion and pick the one most relevant aspect of the debate then I have to go back to the foundations of DIR.

DIR was developed specifically to be a statement of best practices -- Indeed within a limited context -- but it started life as the first and only clear statement of best practices we had. From the very beginning it was also a cult of personality but fortunately for the diving community the DIR heavy weights were also exceptionally skilled divers (and sadly, exceedingly poor communicators, but we've mostly put that behind us now).

The problem with DIR is this. It became a cook book. The divers who developed it were very much interested in best practices but the (less experienced) divers who adopted the system were much more interested in conforming to expectations.

Enter RD. RD was initially developed because the dive computers we had at the time were... well ... ****. Even up to about 2005 or so most of the technical computers on the market were unreliable crap. A solution -- a best practice -- was necessary to compensate for the need for flexibility. RD had its hayday between ... let's say ... 1995 and 2005 because it was the best practice.

Since 2005 there have been several very good computers developed. I don't think I need to name them but we all know what I'm talking about. Since 2007 or so we've also had a very fruitful discussion about deco algorithms for technical diving and with respect to ascent protocols new "best practices" have been emerging.

And THERE is the disconnect. Where DIR started life as away to encapsulate best practices it became engraved in stone by those who do not understand it. The early DIR heavy weights are now out of the scene and the flexibility to incorporate best practices has completely disappeared. All that is left is an out of date cook book.

If the DIR founders were still active then we would have abandoned RD years ago and adopted the computer. The computer is better. Even the study that stacked the deck in favour of RD and self proclaimed its intention to prove that RD was superior proved that the computer is superior. This SHOULD be adopted as the best practice but because DIR is a cult of personality AG's opinion is leading for a lot of DIR divers and I see people -- good and intelligent people -- like Daniel defending a bad practice instead of adopting a new best practice. This is, frankly, incredibly sad.

The way I see it, AG is WAY behind the best practice curve at this point and is severely paradigm locked. A paradigm shift is necessary within the DIR community but who will stand up and take the challenge?

R..

Thanks for the kind words, and the thoughts.

In fairness though, I know very well that RD is not perfect or as accurate as a computer
I just find it very practical myself and actually believe that in terms of developing divers, it is a very powerful tool.
But I should probably say I don't have a problem with divers who prefer computers - far from it.
And I started out in tech diving with one, myself.

It has nothing to do with Andrew Georgitsis as a person.
It's not about a person, and it's not cultism - heck, I can use any computer with an algorithm of my choosing, for my own diving, and/or to run courses, if I wish to.

UTD is not telling me I have to use RD.

And I should definitely also point out that the Spisni study was very much a legitimately scientific study independent of UTD - judging by the report, I'm fairly convinced they weren't out to makeup RD

 

[UWSojourner]

Yes, absolutely, fair enough. I don't have a problem with that, it's just asterisks and footnotes from there.
Such as ...

... we can't assume a qualitative linearity in the stops distributed

What does this mean?

... or, we should wish to see the results of doing a GF30/85 with the same runtime to confirm that this didn't produce any negative change also

Same runtime as what? The 'Gold Standard UTD-RD' profile that should have been tested? Or the *UTD-RD* profile that was tested?

... or, the above is not the same as inverting the statement to mean that because of the arbitrary addition of time, RD must be 44% less effective than GF30/85.

I suppose you need to define what 'less effective' means. In the study the end point was markers of decompression stress. Clearly the tested *UTD-RD* profile was less effective (even though granted more time) than the GF30/85 profile based on the test criteria.

Also, can you share the 'Gold Standard UTD-RD' 1.0 and 2.0 profiles for the 50m 25 min dive with the gases used in the test? How different is it from what AG/BB seemed to think was UTD-RD?


*UTD-RD* = AG/BB determined UTD-RD profile not accepted by Dan_P as real UTD-RD