DIR- GUE GUE standard for gradient factors?

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boulderjohn

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The man is really high up in TDI food chain and as far removed from DIR as they come.
Final point in response: Mark is recommending deep stops for NDL diving. The GUE representative who explained Min Deco to me emphasized that it is not a deep stops profile and is not based on a belief in the benefit of deep stops in NDL diving.
 

ginti

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Despite that, DAN Europe does recommend deep stops, based on those two studies that are considered to be flawed.

I am surprised to hear this; do they recommend it in some official documents that I can find online?
 

Manatee Diver

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A deep stop on a technical profile, particularly the deep hypoxic trimix dives and simulations used to write the deep stops = bad studies are often deeper than the max depth on recreational profiles, particularly those used for the deep stops = good studies.
 

CAPTAIN SINBAD

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My original intent was to write an article on deep stops in recreational dives, and I finally decided that I could not do so because the research was simply not there to say anything one way or the other. The standard approach of an ascent at a safe rate with safety stops on some dives has more than 100 years of research behind it showing it to be pretty darn safe. There is no good research showing any advantage to any other ascent profile that I know of.

If you think about it, such research getting definitive results would be truly daunting, and since the traditional approach works so well, there is no real push to improve it.

I know at least two divers who used to get bent while staying within the NDL of their computers. He was showing a milder DCS hit while she went straight to the chamber. They both started diving using O2 within the NDL to avoid the symptoms. I am not sure if it was DAN USA that recommended it but they both switched from the computer profile to GUE style profile with staggered stops. Symptoms in both of them went away. He told me that ever since he used the GUE style ascent, the difference in post-dive fatigue was so pronounced that just on back gas it worked better than his pure O2 stops.

Neither of them are GUE or UTD but the modification they made to their ascent profile to avoid symptoms was exactly what GUE and UTD emphasize. This is also totally in line with the DAN study that Mark Powell from TDI was also advocating. There were reduced bubble scores in multiple divers to show this.

I somehow partly agree that shallow stops on recreational dive are "pretty darn safe" but we have to further define what we mean by "pretty darn safe." I have manuals from DIR type agencies and also from more mainstream agencies and there seems to be a major communication gap due to language and terms each prefer to communicate with. Every time we use terms like a "hit," it tends to suggest something sudden and something noticeable. In reality the most common symptom of a "hit" would be lethargy. This is a very everyday phenomenon and when such a "hit" occurs to divers within NDL, then they are not knowledgeable enough to attribute it to DCS.

If microscopic bubble blockages after a shallow dive within NDL are causing a 2% decrease in your normal energy levels, then is that something you can even consciously notice? How about 10% loss in your normal energy levels? How great of a loss of energy do you have to experience after a dive that you will attribute, not to the exertion done during the dive, but to decompression stress? When in the progression of lethargy do you say "This is not due to exertion but gosh I am bent!"

In North Carolina dive boats, everybody sleeps on the way back. Almost Everybody! Why is that? Are we as a nation so accustomed to napping at 2:00 in the afternoon that moment the dive on U-352 is over, everyone falls asleep? Would the same people be sleeping at the same time if they were at home running around in the backyard or chasing their dog? Why don't the same people take these 2:00 pm naps after Florida dive charters to that shallow reef? They swim and exert so much more on Florida trips as compared to the NC trips because bottom times in shallow dives are longer then why do they all sleep on the latter and not the former?

I do a lot of heavy weight lifting with bench presses and dead lifts and circuits and after that, I get in the pool to swim laps. I feel very awake after that. Diving specially deep diving has a different effect. It knocks me out.

UTD mindset is that we are all bent! When we use the terms "silent bubbles" or "non-symptomatic bubbles" then we are talking about bubbles in people who sleep on the way back from NC dive trips. They sleep at night like a baby and say "I always sleep so well during a dive." DIR community generally interprets DCS as a gradual build-up of symptoms rather than something that will suddenly occur after the NDL in the form of a "hit."

So yes, if you are trying to avoid a "hit" and you have interpreted that to mean something sudden and drastic that will occur right after crossing NDL then the standard, conventional approach is pretty safe and so is GUE and UTD style stops. But if you are trying to reduce decompression stress within NDL then the scattered stops all the way up MAY have some merit. I know two bent people who "unbent" themselves by incorporating these.
 

CAPTAIN SINBAD

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Wow! That’s f*cking harsh. Especially since you don’t know all the details of Trace’s incident. I hope Karma reads your comment.

I would not wish bad on anyone but you are correct. From what I know about the incident, Ratio Deco did not have anything to do with that unfortunate incident.
 

marsh9077

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Gradient Factors in a Post-Deep Stops World

Interesting article from GUE

In big bold letters in the middle of the GUE article it says:

"The emerging body of evidence against deep stops suggest common gradient factor setting should be modified to de-emphasize deep stops."

"However, since about 2005, evidence has been accumulating from comparative decompression trials that shows deep stops are not more efficient, and possibly less efficient, than shallow stops."
 

marsh9077

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and another one for your viewing pleasure

Evolving Thought on Deep Decompression Stops

Interesting quote at the end from Research Chair in Hyperbaric and Diving Medicine, Laval University, Quebec and former DAN Research Director Dr. Neal Pollock:
“No deep stops! By slowing down deep, all you are doing is adding more time that you’re on-gassing into your slow and intermediate tissues that aren’t saturated. So deep stops have not been shown through any credible research to be in your best interest”
 

p_kos

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and another one for your viewing pleasure

Evolving Thought on Deep Decompression Stops

Interesting quote at the end from Research Chair in Hyperbaric and Diving Medicine, Laval University, Quebec and former DAN Research Director Dr. Neal Pollock:
“No deep stops! By slowing down deep, all you are doing is adding more time that you’re on-gassing into your slow and intermediate tissues that aren’t saturated. So deep stops have not been shown through any credible research to be in your best interest”
Yup, I prefer a low GF of 50 these days.
 

CAPTAIN SINBAD

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This subject, in the context of technical dives has been debated a million times on here. GUE and modern science are at odds and the four part series by Jablonski is GUE's official take on this. UTD has adopted higher gradient factors in their RD 3.0 and are therefore more in line with modern decompression theory in comparison with GUE.


Recreational NDL dives are a different matter. Not enough research has been done to make a conclusive case either way.
 
https://www.shearwater.com/products/teric/
http://cavediveflorida.com/Rum_House.htm

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