My Journey into UTD Ratio Deco

[victorzamora]

@victorzamora , the Spisni Study showed the profile with the deeper/longer Deepstops had the greater significance of inflammatory protein markers: That profile was RD with 42min of overall deco time vs the Bühlmann GF profile with 30min of overall deco time.

So you agree that the Buhlmann profile was more effective, correct? You also agree that the Buhlmann profile took less time, correct?

Efficiency has two factors: Effectiveness and Time. Specifically, it's Effectiveness per Time that defines Efficiency.

The two factors are FAR from mutually exclusive.

 

[Dan_P]

Dan_P it has everything to do with AG since he invented it and is the one trying to defend it in the face of science that says it doesn't work. It goes in a string of concepts that he has to market himself, his gear, and his agency vs. trying to actually make the most efficient ascent profile.
I am saying literally that anyone who uses Ratio Deco is dismissive of science because that literally is what RD is. AG saying that he knows better than science and medicine so you should believe him because he's better. That is LITERALLY what he's said in multiple interviews/youtube videos he's posted about Ratio Deco, etc etc. It all comes down to "the algorithms and science are wrong, Ratio Deco works because I don't get bent and I do it based on how I "feel" and you should do the same because I'm a Diving God and know better than those silly scientists". If you want to believe that fine, but don't tell me it's the most effective or efficient way to manage an ascent profile, because no one doing serious dives is following that garbage.

I'll ignore the vast majority of the sentiment you're expressing and focus on the following:

You're saying;
"...don't tell me it's the most effective or efficient way to manage an ascent profile...", when all I've said was let's stay on topic.

Just discuss the topic at hand and it'll be a much more interesting discussion for everyone.

That's all.

 

[Kevrumbo]

@Kevrumbo so with that last narrative, how does that make a profile that was almost 50% longer that showed a statistical difference in decompression stress markers as more efficient?
I'll take the shorter, less stressful one as more "efficient" and since it had less stress markers, more "conservative". Unsure how you can believe one that is longer and exhibits more signs of decompression stress as more conservative

A more pragmatic approach than whatever rubbish you are trying to present is to simply use the algorithm that works.

So you agree that the Buhlmann profile was more effective, correct? You also agree that the Buhlmann profile took less time, correct?

Efficiency has two factors: Effectiveness and Time. Specifically, it's Effectiveness per Time that defines Efficiency.

The two factors are FAR from mutually exclusive.

Efficacy, is the extent to which a desired effect is achieved; the ability to produce a desired amount of the desired effect, or the success in achieving a given goal. Contrary to the term efficiency, the focus of efficacy is the achievement as such, not the optimization of time or resources spent in achieving the desired effect. Therefore, what is effective is not necessarily efficacious, and what is efficacious is not necessarily efficient.

Again . . .if you believe that protecting the Fast Tissues from supersaturation is important as per the tenets of RD, you will be taking a relatively more conservative approach in its implementation in order to compensate for the loading and surfacing supersaturation later of the Slow Tissues. Is that clear? Y'all understand that?

For my application at that time (Truk Feb 2015), I chose the "efficacy" of progressively extending out my shallow O2 deco stops on RD 1.0 after consecutive days of two mandatory staged deco dives per day in order to reduce surfacing and residual inert gas tensions on the Slow Tissues, with the use of a Sherwater Petrel Computer running in parallel GF30/85 and electively decreasing the GFhi surfacing value to 70 or 60 during the O2 stops (refer to post #329 Deep Stops Increases DCS)

 

[LiteHedded]

Efficacy, is the extent to which a desired effect is achieved; the ability to produce a desired amount of the desired effect, or the success in achieving a given goal. Contrary to the term efficiency, the focus of efficacy is the achievement as such, not the resources or optimization of time spent in achieving the desired effect. Therefore, what is effective is not necessarily efficacious, and what is efficacious is not necessarily efficient.

Again . . .if you believe that protecting the Fast Tissues from supersaturation is important as per the tenets of RD, you will be taking a relatively more conservative approach in its implementation in order to compensate for the loading and surfacing supersaturation later of the Slow Tissues. Is that clear? Y'all understand that?

For my application at that time (Truk Feb 2015), I chose the "efficacy" of progressively extending out my shallow O2 deco stops on RD 1.0 after consecutive days of two mandatory staged deco dives per day in order to reduce surfacing and residual inert gas tensions on the Slow Tissues, with the use of a Sherwater Petrel Computer running in parallel GF30/85 and electively decreasing the GFhi surfacing value to 70 or 60 during the O2 stops (refer to post #329 Deep Stops Increases DCS)

That’s the whole thing Kev. No one believes that...

I mean OP asked for the opinion of “some of the highest level technical divers on here” and that’s what he’s getting. They just disagree with your (and utd’s) opinion when it comes to dive planning

 

[victorzamora]

Therefore, what is effective is not necessarily efficacious, and what is efficacious is not necessarily efficient.

I disagree. Effective = efficacy. If something is effective, it is efficacious. They're synonyms.

But, to your overarching point, I still think we're misunderstanding eachother. It sounds like you're saying you'll gladly give up speed for increased safety. What matters with regards to efficiency is how effective your time spent doing deco is.

 

[CAPTAIN SINBAD]

So just to keep things in focus, can we agree on the following statement:

While ratio decompression falls apart over extended depths and long exposures, the limits that UTD imposes at the Tech 1 level (160 ft depth, maximum of 15 mins deco on pure O2, 30 minutes on 50 % with standard gases of 25/25 21/35 and 18/45) would prevent ratios from deviating drastically apart within these parameters.

The only exception I can think of is when Min-Deco schedule for 32% is also used for 25/25. Am I correct in my skepticism that this 7% difference in oxygen should mean a totally different min-deco schedule for 25/25? @Dan_P @LiteHedded @PfcAJ @Kevrumbo @tbone1004 @boulderjohn anyone else with a strong opinion on this one?

Thoughts?

 

[Kevrumbo]

guys dont get caught up with kevrumbo's nonsense. he'll talk in circles and italicize and bold things till the cows come home. round and round you go. this is the guy who bent himself diving ratio deco more than once and got disowned on the utd forum for doing it all on air. i'd say he's as much an authority on UTD as I am.

That’s the whole thing Kev. No one believes that...

I mean OP asked for the opinion of “some of the highest level technical divers on here” and that’s what he’s getting. They just disagree with your (and utd’s) opinion when it comes to dive planning

Well it seems obvious now in hindsight @LiteHedded , and y'all experts on "second-guessing" and "schadenfreude" at my example & misfortune. . . (I'm simply recapping the history of how we got to this point as well as my own anecdotal experience with RD 1.0 from 2007 to 2015).

As for the belief in Deepstops:

Bruce Wienke of the RGBM Model had a seemingly compelling argument in this monograph on deepstops:
http://tecvault.t101.ro/Deep_Stops-BW.pdf

The first four paragraphs in the above linked article are particularly damning and now "cringeworthy" (the claim that deepstops can result in the overall shortening of decompression times -no wonder we haven't heard from BRW in a while. . .) all in the context of the unexpected results of the NEDU Deepstops Study.

I disagree. Effective = efficacy. If something is effective, it is efficacious. They're synonyms. . .

It depends on the semantic context: neither words "effective", "effectiveness", nor "effectively" inform about the direction (positive or negative) and the comparison to a standard of the given effect. Efficacy, on the other hand, is the extent to which a desired effect is achieved; the ability to produce a desired amount of the desired effect, or the success in achieving a given goal. (It's nitpicking trivial semantic subtlety, but that's my take on it and how I use it in this instance. . .)

But, to your overarching point, I still think we're misunderstanding each other. It sounds like you're saying you'll gladly give up speed for increased safety. What matters with regards to efficiency is how effective your time spent doing deco is.

Vic, with regards to the NEDU Study and decompression algorithm efficiency, what matters most is whatever gets a Navy Diver or SEAL Team quickly recovered from the surface -especially in a "denied operations area"- with the least amount of in-water decompression time at depth, for an "isorisk" allowable level of peak Fast Tissue supersaturation early in the deco profile and minimal Slow Tissue integral time of supersaturation upon surfacing.

For myself, the insurance and conservatism of efficacy is important for me, for however long it takes -Even starting with a de-emphasized deepstop GF 50/80 or perhaps 75/75 (and using a de-emphasized RD 2.0 profile in Wetnotes as back-up), now if I can reset my surfacing GFHi on-the-fly to 70 or 60 with a Petrel/Perdix to electively extend an O2 stop with a plentiful AL80/11L cylinder supply of Oxygen, along with favorable environmental, weather, sea state and thermal considerations -I would do so.

So just to keep things in focus, can we agree on the following statement:

While ratio decompression falls apart over extended depths and long exposures, the limits that UTD imposes at the Tech 1 level (160 ft depth, maximum of 15 mins deco on pure O2, 30 minutes on 50 % with standard gases of 25/25 21/35 and 18/45) would prevent ratios from deviating drastically apart within these parameters.

The only exception I can think of is when Min-Deco schedule for 32% is also used for 25/25. Am I correct in my skepticism that this 7% difference in oxygen should mean a totally different min-deco schedule for 25/25? @Dan_P @LiteHedded @PfcAJ @Kevrumbo @tbone1004 @boulderjohn anyone else with a strong opinion on this one?

Thoughts?

I would still insist on using Oxygen to clean up even using the Eanx32 Min Deco Table for 25/25 bottom mix, because of the Helium. . . I'd rather not deco out on backgas 25/25 alone because of Helium's greater diffusivity, and the hazards of contracting the "chokes" even diving it within "no-stop NDL" Triox limits.

 

[PfcAJ]

So just to keep things in focus, can we agree on the following statement:

While ratio decompression falls apart over extended depths and long exposures, the limits that UTD imposes at the Tech 1 level (160 ft depth, maximum of 15 mins deco on pure O2, 30 minutes on 50 % with standard gases of 25/25 21/35 and 18/45) would prevent ratios from deviating drastically apart within these parameters.

The only exception I can think of is when Min-Deco schedule for 32% is also used for 25/25. Am I correct in my skepticism that this 7% difference in oxygen should mean a totally different min-deco schedule for 25/25? @Dan_P @LiteHedded @PfcAJ @Kevrumbo @tbone1004 @boulderjohn anyone else with a strong opinion on this one?

Thoughts?

I don’t know what UTD is teaching for RD using oxygen for deco. 160’ max depth with a max time of 30mins on 50% is probably workable for a 1:1 ratio provided you get rid of that silly deep time.

But you can work it out yourself by compairing what buhlmann (gradient factors of your choice) puts out to the RD schedule.

Pretending that 32% and 25% oxygen results in the same decompression is preposterous though.

 

[tbone1004]

@CAPTAIN SINBAD think back to your nitrox class. Does a 7% decrease in inert gas change your no decompression limit? Isn't that why we dive nitrox in the first place to get a shallower EAD?
If the min-deco schedule was made with 25/25, then sure you can use 32% with no issues, but when it's based around EAN32 and used with a higher fraction of inert gas, then it doesn't work.

@Kevrumbo are you saying that something published in 2012, based on research done in the 90's is more applicable than research published based off of experiments within the last couple of years? NAUI's insistence on teaching RGBM because Bruce is on the board and Tim owns NTEC is the reason they are not a relevant technical agency. Of importance to emphasize this is the fact that the current NAUI training director was a consultant on the foundings of NTEC, and has certified hundreds of technical divers, but has NEVER issued a NAUI technical cert despite being fully capable of doing so since the inception of NTEC.

 

[Patoux01]

think back to your nitrox class. Does a 7% decrease in inert gas change your no decompression limit? Isn't that why we dive nitrox in the first place to get a shallower EAD?
If the min-deco schedule was made with 25/25, then sure you can use 32% with no issues, but when it's based around EAN32 and used with a higher fraction of inert gas, then it doesn't work.

Actually, with different half-times for He and N2, you could get an explanation for being able to use the same times for 25/25 and 32. I believe playing with this fact has been used on very long dives (24hours) by Laurent Ballesta.


Not saying what's right or wrong, just saying that it could turn out to make no difference, depending on what "religion" you're following.