UTD Decompression profile study results published

[Kevrumbo]

Sorry what?
View attachment 403295
(from Huwporter UTD Decompression profile study results published )

Does anyone have the "third" graph from above - ie UTD-RD(TM) vs GUE? And perhaps even a fourth with all 3 profiles on one? Would be interesting to view but I'm not infront of a computer to do it myself...

-Mark

Yes, that makes sense... so perhaps more accurately combining the graphs of the UTD-RD(TM) algorithm vs the ratio profile that uses your view of the methodology discussed by GUE to generate a 30/80 profile "on the fly"?

From my interpretation of his post, Kevrumbo is suggesting that the "GUE-style" profile is basically the same as the UTD one, which from the graphs posted doesnt initially appear to be the case... and so putting both on the same graph would allow a closer comparison (for my poor eyes at least).

But I take your point about cutting with an axe etc, and perhaps its not a particularly useful comparison in the context of this thread anyway - as I understand it the UTD-RD(TM) is treated as a decompression algorithm, which was compared to the Buhlmann 30/80 algorithm. "GUE-style" ratio deco methodology has been brought in slightly erroneously, as its a methodology used to generate on the fly plans that mimic your algorithm of choice within certain conditions (and here the example is the 30/80 profile). I have no particular knowledge of the history of DIR / GUE / UTD etc so its all interesting to me, particularly how the different terms have become conflated.

-Mark

Yeah, you have that pretty straight.

View attachment 403298

Maybe I'm wrong. Explain how RD, which as far as I know hasn't changed in the last 15 or 20 years, somehow magically mimics Buhlmann with some kind of gradient factors now when it never has before.

Would you care to explain the process by which the bubble approach has been "let go" and RD now approximates Buhlmann?.... because I'm not seeing it.

I could be wrong about this (and I sincerely hope that I am to be perfectly honest) but I would like to see incontrovertible proof that I am wrong. How do you adjust RD to accommodate "your algorithm of choice"?

R.

GUE Ratio Deco, and UTD Ratio Deco without any Deepstops or S-curve shaping:

@50m for 25min bottom time on 18/45 standard gas and two deco gases Eanx50 and O2, GUE has 15min with 50% and 15min with 100% O2, while UTD has 17.5min on 50% and 17.5min on 100% O2 -or nearly the same Eanx50 and O2 time schedules for both versions of Ratio Deco.

Depth: GUE: UTD:
21m, 3min, 3.5min [Eanx50]
18m, 3min, 3.5min;
15m, 3min, 3.5min;
12m, 3min, 3.5min;
9m, 3min, 3.5min;
6m, 15min, 17.5min [Oxygen]
Or optionally:
6m, 9min, 11.5min [Oxygen]
3m, 6min, 6min [---> a surfacing ascent rate from 6m at 1 meter per minute].

Now compare the above with a generated Buhlmann GF 50/80 (as currently recommended for de- emphasizing deepstops) for the same bottom profile and let's see how it looks. .

 

[Patoux01]

GUE Ratio Deco, and UTD Ratio Deco without any Deepstops or S-curve shaping:

What if if that was that exactly that made them different? Are you still gonna say they're the same?

A cow is a mammal, I'm a mammal, but I don't think we're one and the same, even if we share some similarities due to us both being mammals.

 

[steady1570]

There is no claim here that the 'GUE'-style profile is better than the GF one - just that it is close enough in the real world, and that
3-3-3-3-3-15
is easier to remember than
1-1-2-3-5-16

Agreed, its a practical get out of the water approach for a change in plan or whatever. I personally use 2 computers but can buy the idea that others prefer "simple" (ok, subjectively) rules that they can use too, and it seems a tool I'd like to have for that really bad day.The comparison graphs (to me) support that view, thanks.

-Mark

 

[Kevrumbo]

What if if that was that exactly that made them different? Are you still gonna say they're the same?

A cow is a mammal, I'm a mammal, but I don't think we're one and the same, even if we share some similarities due to us both being mammals.

Because UTD's version had the longest and deepest of all applied deepstop bubble models which was shown by the NEDU Study to be disadvantageous to the slow tissues, I propose for the moment to discard or modify them with a slowing ascent rate and no S-curve as per standard operating procedure of GUE's Ratio Deco. . . And so yes, therefore for 25min at 50m on 18/45 bottom mix and 50% & 100% O2, the two RD "flavors" should be the same or similar.

 

[Patoux01]

Please, do not add to the confusion.

What has been tested is NOT what you are showing, UTD-RD has little to do with other RD rules. They are very different. The fact that you believe the correction to apply to UTD-RD is to make it into GUE-RD does not, by any stretch, change what has been tested. So please stop posting that "see, this is UTD if you remove everything that is UTD, and this is GUE, see how similar? They're the same!". They are not the same. Maybe UTD-RD 3.0 will be the same as GUE-RD, but the current one we can see, and has been tested, is not. Not by any stretch.

 

[Kevrumbo]

Please, do not add to the confusion.

What has been tested is NOT what you are showing, UTD-RD has little to do with other RD rules. They are very different. The fact that you believe the correction to apply to UTD-RD is to make it into GUE-RD does not, by any stretch, change what has been tested. So please stop posting that "see, this is UTD if you remove everything that is UTD, and this is GUE, see how similar? They're the same!". They are not the same. Maybe UTD-RD 3.0 will be the same as GUE-RD, but the current one we can see, and has been tested, is not. Not by any stretch.

There is no confusion if you understand the implications of the NEDU Deepstops Study, so the motivation should be to de-emphasize them just as GUE's RD version did . . . Doesn't that proposition make sense to you??? Why "beat the dead horse" of UTD's 75% and 50% max depth mandatory "hard" deepstops when the NEDU Study has definitively shown -even more so than this current test stated in this thread and the OP- that this is not an efficient strategy?

 

[Patoux01]

I'll quote @steady1570 here: "From my interpretation of his post, Kevrumbo is suggesting that the "GUE-style" profile is basically the same as the UTD one, which from the graphs posted doesnt initially appear to be the case... and so putting both on the same graph would allow a closer comparison (for my poor eyes at least)."

You're presenting "what you believe UTD should do vs what GUE does" when people ask for "What does UTD do and what does GUE do". You do a lot of arm-waving by putting billions of figures in your posts. The only issue with those figures is that they're irrelevant. We don't care what you wish people do, that's not what has been asked.

 

[steady1570]

There is no confusion if you understand the implications of the NEDU Deepstops Study, so the motivation should be to de-emphasize them just as GUE's RD version did . . . Doesn't that proposition make sense to you??? Why "beat the dead horse" of UTD's 75% and 50% max depth mandatory "hard" deepstops when the NEDU Study has definitively shown -even more so than this current test stated in this thread and the OP- that this is not an efficient strategy?

Can I suggest that, as @Patoux01 notes, you are not commenting on what this study set out to measure (the difference in outcome for two decompression strategies, UTD-RD as implemented by AG etc and Buhlmann with 30/80 GF), but more what conclusions we should draw from it, namely that profiles that emphasise deeper stops are not as "good" (by whatver chosen metric) as those that do not, which is consistent with the NEDU deep stops study.

Bringing in the "GUE-style" method for approximating other deco algorithms, whilst perhaps interesting from a historic or commentary point of view is slightly irrelevant? And perhaps you are suggesting that there is no need to throw the whole UTD-RD framework out, as there are similarities with, for example, the "GUE" approach that might mean it is useful in the light of experimental results, but again, thats a slightly different (albeit interesting) topic.

-Mark

 

[Remy B.]

I don't know what is so difficult to remember short Deco profiles, another way to do it is a stair calculation you just have to remember where your 1st stop starts with GF and what is the amount of time at 6m, by knowing the total time @ 6m you know that the one at 9m is half of that and that the one of 12m is the half of the one @ 9m, and with short profiles everybody knows that at 21m with 50% most of the time you start with 2min then to go back to 1min

if your first stop starts at 28m you stop for 1min
25m @ 1min
21m @ 2min switch to 50%
18m @ 1min
15m @ 1min
12m @ 5min
9m @ 9min
6m @ 17min

that stair profile is closer to a GF than a RD that on-gasses unnecessarily deeper.


Let be honest here, none of the RD practitioners here in SB will use it on seriously Deep and long dives, because you know that if you apply RD that deep you will be still on-gassing by stopping that long that deep, if you don't have a DC for sure you have a slate with a software profile on it and a bottom timer.

 

[StefinSB]

What matters. . . As the practical solution is with any Bubble Model algorithm of which UTD's RD had the history of the longest & deepest deepstops, you're gonna have to extend & pad your O2 deco stops to effectively decompress the surfacing slow tissue tensions if you choose to use RD.

Objectively, I think just in general, the above advice is a practical option for any deco algorithm in use, and especially a solution for anyone still choosing to use RD.

Correct observation but wrong conclusion imo. If you have have to pad a model with an arbitrarily chosen variable you should discard the model or at the very least change it to make it describe reality a bit better.