My Journey into UTD Ratio Deco

[kensuf]

100% agree with you, but unless you're part of that "club" DIR means whatever AG says it means to the public...

Then "DIR" has become a meaningless phrase.

I've never been a fan of the phrase anyway. I have always preferred Hogarthian.

 

[LiteHedded]

Then "DIR" has become a meaningless phrase.

I've never been a fan of the phrase anyway. I have always preferred Hogarthian.

DIR is like pornography. You know it when you see it.

 

[kensuf]

Agreed. Convolution isn't sexy.

 

[Dan_P]

It's a string about Ratio Deco.
Not even that - it's a string about a diver's experience exploring questions about it, from "the horse's mouth", and sharing the answers obtained in the process.

If you don't dive Z because you think frequency of failure is more important than impact of failure, or have no money to buy more gear/training with, or think you have nothing more to learn about anything, or if you don't want it because you're solo-diving, or whichever reason; bene - it's your call!
But take it up in a string about the Z-system, then.

If you don't like Andrew Georgitsis personally, give him a call, send him an email or whatever.

But this is about Ratio Deco - just play the ball.

 

[tbone1004]

Then "DIR" has become a meaningless phrase.

I've never been a fan of the phrase anyway. I have always preferred Hogarthian.

agreed, however it is funny that Bill doesn't dive what we consider a "hogarthian" rig.
Agree on the Z-system but he does state that it's DIR and no one has come out to tell him that he can't use it....

@Kevrumbo as said above, total time in water does not mean more conservative. More conservative is viewed by different algorithms as their "priority limit". Buhlmann is a supersaturation, VPM is a bubble size, etc.. RD does not factor any of that in since AG said it came about as "what makes me feel good when I surface", so there is no science backing up any of those strategies, literally it is just what doesn't make AG feel bad when he comes up and whatever is going on in his head that makes sense to him.

@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.

 

[victorzamora]

A) more efficient, and B) more conservative.

No @JohnnyC , the Spisni Study blew AG's own expectations "out of the water" and implied to an extent that A) & B) above are actually mutually exclusive.

Actually, I very much disagree with you on this, @Kevrumbo. Speed is NOT the same as efficiency. Efficiency and conservatism are extremely related. Conservatism is how safe you are and efficiency is how quickly you can get out at a given conservatism (isorisk). Efficiency isn't about speed alone. The Spisni study absolutely proved that more time in the water did not mean a dive was more conservative, ie: the dive with 44% longer deco had worse results.

A profile with greater efficiency would be isorisk with a shorter deco time OR same deco time for less risk.

One quick note: I hate the use of the term "conservatism" in deco theory because I think it gets over-used and over-simplified.

 

[Kevrumbo]

Actually, I very much disagree with you on this, @Kevrumbo. Speed is NOT the same as efficiency. Efficiency and conservatism are extremely related. Conservatism is how safe you are and efficiency is how quickly you can get out at a given conservatism (isorisk). Efficiency isn't about speed alone. The Spisni study absolutely proved that more time in the water did not mean a dive was more conservative, ie: the dive with 44% longer deco had worse results.

A profile with greater efficiency would be isorisk with a shorter deco time OR same deco time for less risk.

One quick note: I hate the use of the term "conservatism" in deco theory because I think it gets over-used and over-simplified.

@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.

My interpretation of this (and also from experience) is that a practical RD implementation must compensate for this inflammatory reaction as well as potential increased VGE -presumably from Slow Tissue Surfacing Supersaturation- by spending "conservatively" a significantly much longer O2 shallow stop profile in order to effectively reduce deco stress on these tissues (Ironically, it was AG who used to deride non-deepstop Bühlmann deco profiles as "bend & treat" algorithms i.e. -ascending earlier/faster and spending a longer time decompressing in the shallow depths). Do you understand the simple logic of my point Vic?

Conservatism is best defined as qualitatively minimizing the risk of overall supersaturation and potential bubbling of both Fast and Slow Tissues; Efficiency of a deco profile is the optimal and acceptable quantitative amount of time limiting supersaturation of a particular tissue. It is now thought that the more perfused Fast Tissues are robust enough and can take the peak tensions and lesser time integral of critical supersaturation earlier in the deco profile without bubbling thus obviating or not requiring the need of deepstops, and therefore making a Bühlmann profile more "efficient". RD claims a strategy of not driving Fast Tissue anywhere near to its M-Value critical supersaturation by using deepstops to prevent potential bubbling is better, thus making its profiles more "conservative" (but as the NEDU Deepstops Study showed, not necessarily optimal later in the profile with regard for the Slow Tissues' surfacing supersaturation tensions).

 

[tbone1004]

@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

 

[Patoux01]

@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.

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

 

[LiteHedded]

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.