UTD Ratio deco discussion

[Kevrumbo]

This is the same old thing.

There's a difference between doing what a model puts out (even if it's adjusted via something concrete like gradient factors) and doing something just because.

No, it's the difference of recognizing and accommodating a paradigm shift, even for Simon Mitchell:
-------quote------
". . .Equally, I do believe the data are strong enough (and bear in mind they are the only data) to consider a change in practice if you are a strong "emphasizer" of deep stops. In practical terms, "de-emphasizing" deep stops (or lessening any potential disadvantage) would mean using bubble models on very high conservatism settings, and with gradient factors, avoiding very low GF-lo values. I have been evolving my own use of GFs and am currently around 50/80 . . .sometimes as low as 70 for the high value when we are at places like Bikini and I am the only diving physician. Pre-NEDU study I was GF lo of 20. This is my personal perception of a sensible graduated response to the way the evidence is currently evolving. I may well go further in future (guided by the evidence).

Sorry about the long post. Hope it makes sense."

Simon M
Deep stops debate (split from ascent rate thread) - Page 13
-------end quote------
[/QUOTE]

 

[boulderjohn]

How about some direct posts from @Dr Simon Mitchell , clarifying what his thoughts are:

Funny, but it sure seems to me that he is basing his decisions on his knowledge of science rather than making
"non-scientific recommendations totally unsupported by science." If he is, indeed, making the decisions on his ascent profiles in his own diving in accordance to factors "totally unsupported by science," I am completely in awe of his ability to do so. Well, "awe" is really not the right word, because if he were a student in my PADI trimix class, we would have problems. That class teaches students to stay abreast of the latest advances in scientific research and adjust their practices accordingly. That is why a few months ago PADI told trimix instructors that they are no longer required to teach to the deep stops standards--the latest research does not support them.

So, if Simon is really basing his personal dive profiles on factors "totally unsupported by science," I can't help but wonder how (or why) he is doing that. I know that if I were even remotely as knowledgeable about those matters as he, I would give that science at least a passing thought as I planned the profiles that could determine whether I live or die. Even if he were to place different dive profiles on a dart board, he might be subconsciously led to aim for the ones supported by he science he knew so well.

OK, sarcasm over. I recently made several posts in response to someone seeking guidance for diving at altitude, something I do know something about. I very pointedly did not make any recommendations, even though I ached to do so. The reason is simple--liability. If I recommend something, the person follows that recommendation, and is then injured--well, who knows? Instead I simply gave facts and let the individual make a decision based on those facts. That is a wise move for any scuba professional.

 

[PfcAJ]

No, it's the difference of recognizing and accommodating a paradigm shift, even for Simon Mitchell:
-------quote------
". . .Equally, I do believe the data are strong enough (and bear in mind they are the only data) to consider a change in practice if you are a strong "emphasizer" of deep stops. In practical terms, "de-emphasizing" deep stops (or lessening any potential disadvantage) would mean using bubble models on very high conservatism settings, and with gradient factors, avoiding very low GF-lo values. I have been evolving my own use of GFs and am currently around 50/80 . . .sometimes as low as 70 for the high value when we are at places like Bikini and I am the only diving physician. Pre-NEDU study I was GF lo of 20. This is my personal perception of a sensible graduated response to the way the evidence is currently evolving. I may well go further in future (guided by the evidence).

Sorry about the long post. Hope it makes sense."

Simon M
Deep stops debate (split from ascent rate thread) - Page 13
-------end quote------

You're totally missing the point.

 

[RayfromTX]

So, do you really think that when he makes a personal decision on how he dives, a decision that could mean life or death for him, that his "guess" has no basis whatsoever in the research he has conducted and reviewed? You believe that his decision is "totally unsupported by science"? How did he shut all of those things out of his mind? It must have been difficult--I know I would have thought about all of that when making such a decision.

Kevin at least says it was an "informed decision," so evidently he does not believe a dart board was involved.

I had to go back and read my post to find where I might have said that his decision was totally unsupported by science and that he shut all those things out of his mind when making his decision. That would have been a stupid thing to say and as it turns out I didn't say that. We have no disagreement-at-all. Dr. Mitchell has repeatedly said that his decision of how to dive is only his best guess based on what he knows but that it is not something that has been scientifically proven by testing.

I went on to add that even if we were able to test "his best guess" it would only be relevant to that control group. Yes, any testing would give us additional evidence to base our guesses on but until they test a control group of 56 year old males with my lifestyle weight, genetic markers and all the other things that affect susceptibility to DCS then for me with my factors it is still just a guess. We can and do add safety factors to account for the variabie and not totally understood factors that contribute to DCS. It is when we try to see how fast we can get out of the water that we need to know how close we can get to the line without going fizzy.

These forums often lead to misunderstandings. I don't disagree with you about this and I know we have both read all of Dr. Mitchell's posts and many of his papers regarding these studies. He is better than either of us at getting his points across in plain English without being emotional and without wording things in a way that can be misinterpreted.
Let me assure you that I in no way tried to communicate that Dr. Mitchell decided his strategy for deco diving with the aid of a dart board but I suspect you already knew that.

If someone thinks at this juncture that there is a right way to do decompression diving and that it is understood and that we have arrived at an understanding of the safest most efficient way to do deco, then they need only go back and read the arguments from 12 years ago. Many of the same people were involved and it is interesting to read how convinced they were then and now even though they have completely changed the way they think.

I am not saying that because it is not totally understood and well tested that we shouldn't study and base our decisions on the best science available but good scientists make a hypothesis, test the hypothesis and keep an open mind about the results. When the data points in a different direction than they expected, they follow the data. That's what science is. That is what has led to the current shift in thinking.

Finally, we will save a lot of time if we just agree to agree, because we do. If you assume I mean things I don't say actually say then I'm going to have to spend the bandwidth to straighten it out and we have better things to spend our time on. In the meantime I'm going to continue to learn from you, Kevin and others because y'all know more about this than me and most of it you actually agree about.

 

[Kevrumbo]

You're totally missing the point.

Other than Simon Mitchell making a personal adjustment to his own deco methods and protocols ostensibly because of implications of the NEDU Study (and UTD presumably based on their own study as well), and that UTD Ratio Deco 2.0 (and GUE "pragmatic" Deco) is proprietary -meaning there may not be full disclosure forthcoming here in an open forum explaining the changes in either method- What is your point?

And @RayfromTX , It's good you see and understand the legitimate gripes and serious concerns coming from @boulderjohn while trying objectively to filter out all the useless political hyperbole and facetious rhetoric.

 

[Diver0001]

I would think that the truth is very likely more banal. 66% is 2/3. Dividing by 3, at least roughly, is easily done in the head. So is 50% but I think the difference we're seeing is that UTD still hasn't been able to let go of the "deep stops are safer" paradigm. Even the step of going from 75% to 66% (divide by 4 to divide by 3) must have seemed like a major innovation to them.

Deep ascent lines from technical dives are not safer. They are less safe. The research is crystal clear. Therefore the question in my mind is, and remains, why anyone would be using RD or *any* "deep ascent" algorithm at all when there are very good computers out there that implement safer protocols -- at this point in time, which we always need to keep in mind.

RD had a function to bridge the gap while computers were being developed to do this stuff. Those computers are there now. RD, therefore, should be retired.

A similar discussion happened (is still happening?) with respect to tables. Many, mostly older, divers are unable to believe that new divers can be competent divers without a knowledge of tables. Letting go of this is proving to be very hard for some people. It's possible that an entire generation may be necessary to make this change.

Some older divers even find it hard to believe that someone could learn enough about deco theory to be safe if they do not understand tables. They do not understand that by letting go of tables, the understanding of deco theory among newer divers, can be brought to a new plateau and that new divers can learn to understand deco theory even better than those of us who learned by rote to calculate a dive on tables. I'm sure in the history of science, that similar "paradigm shifts" were necessary when calculators were invented or computers were invented and with similar arguments, "letting the machine think for you".

It's human nature to resist change. Not always but often..... and often the most vocal among us are the least open to innovation. This is happening with UTD but I see it even in the PADI system where instructors are now required by standards to teach the OW course neutrally buoyant and the resistance to doing so is profound for no better reason than "what we did before worked fine" (which, incidentally, it did not if you compare it to the results of neutral teaching).

There are always a relatively small number of people in this world, in my experience, with the flexibility of mind and spirit to easily make or even initiate a paradigm shift, and I'm sorry to say that I don't believe that AG is one of them. Going back to the PADI example, I think of their 100,000 instructors, a marginal number have *really* made that change. This is about what I would expect among the thoroughly indoctrinated within UTD too... maybe 1%, maybe 2% especially if their leader is not with in the 1%.

"What worked in the past must work now and will work in the future". Innovations are often met with (and correctly) skepticism. However, with enough proof the innovation must be accepted and integrated into a new paradigm. In my opinion, we, as divers, are relatively slow to accept change and when the risks are high, as they are in technical diving, then we are not only slow. We are glacially slow. To my way of thinking, this is why UTD is so far behind the curve with respect to their understanding of deco theory. The results of newest research does not meet their "expectations" and therefore the results are being ignored.

So we divide by 3 instead of dividing by 4 and we pride ourselves on being innovative even though we are not.

R..

 

[RayfromTX]

Is it so very different than when calculators came out and those that had built their understanding around the use of a slide rule insisted that learning the slide rule was important to understanding how numbers work? That didn't last very long as I recall.

I decided that learning tables was important while my wife called bs on tables and paper log books from the moment she heard about them. She is also the one that pushed for getting the Perdix. People see things differently. Finding the similarities and learning to use them to form a basis for cooperation and team building matters far more than who is right. BTW, I don't think that just because we hide the algorithm inside a magic box on our wrist makes it immune to being based on incomplete and potentially faulty reasoning.

Especially in regards to subjects that are not completely understood, the need to believe that someone knows so that we can hang our hat on their understanding is not "scientific". It is closer to religion.

 

[RayfromTX]

And @RayfromTX , It's good you see and understand the legitimate gripes and serious concerns coming from @boulderjohn while trying objectively to filter out all the useless political hyperbole and facetious rhetoric.

I will never get to where you and John are in my scuba diving. I respect both of you and your knowledge.

I think we would all get more out of these discussions if we refrained from attacking each other. We would also be likely to reduce the level of defensiveness and increase the depth of the discussion if we could improve the signal to noise ratio.

As an example, the question is asked "How does RD train to deal with deco diving at altitude? Do they have an official protocol that they use or do they ignore it?" 200 posts later I still haven't seen a clear response from a knowledgable source that can show published info on how or if it is taught. We somehow came to an understanding, sort of, that they think it should be compensated for but you are on your own as to how. If in the hundreds of posts I missed a clear answer or an official response to this question I would love to see it. The problem is the tone of the question. It can be heard by those invested in RD as something like "does rd believe that altitude matters or do they still suck?" "do any of you crazy people still using it know how wrong it is?"

Nobody is guilty or innocent of creating this dynamic. I have learned as much Simon Mitchell about communicating clearly and respectfully on a topic when I am being attacked as I have about deco science.

We should ask ourselves these questions before we post a question to a hot topic.
What do I want to learn?
How will my audience hear my question as I have it worded?
Will that get me the response I need to in order to learn?
How can I word it so they will feel respected and I can learn from them?
Not agreeing with them makes all of those questions more important, not moot.

 

[Patoux01]

I think we would all get more out of these discussions if we refrained from attacking each other.

 

[RayfromTX]

You mean new here on earth? This ain't no different than any other board or board room for that matter. Beating people over the head leaves you with wary people that avoid you or people surrounding you that have a tolerance for having their heads beaten.