UTD Decompression profile study results published

[JohnnyC]

It's important to note that Ratio Deco as taught by GUE is different that the coathook abortion that UTD calls Ratio Deco. It doesn't surprise me that it has been demonstrated to be entirely incorrect.

Between their sidemount "isolator" and their ridiculous attitude towards flying a rebreather I don't know why anyone would take anything that comes out of AG's mouth seriously.

 

[lv2dive]

Was AG with GUE or UTD at the time? I'm just curious, I've not heard of GUE teaching RD exclusively but it may well have been taught that way before my time and/or when AG worked for GUE.

This is quite the opposite of the Ratio Deco class I took from Andrew. When we worked out a deco profile using ratio Deco, another UTD instructor in the room would do the same profile using one of several different commercial deco software programs. They never matched. According to Andrew, that showed why you should never use a commercial deco software program. Since RD is perfect, the fact that it never matched a commercial program showed that all those programs were defective.

 

[KevinNM]

View attachment 402776

'Science advances one funeral at a time.'

Or the full version from Planck
"A new scientific truth does not triumph by convincing its opponents and making them see the light, but rather because its opponents eventually die, and a new generation grows up that is familiar with it."

 

[tursiops]

Several posters want to see the actual report. It was cited in the OP, as:
Spisni E et al. A comparative evaluation of two decompression procedures for technical diving using inflammatory responses: compartmental versus ratio deco. DHM 2017;47(1):9-16.
It is not publically available yet; there is a one-year embargo before the full journal issues are released. See:
DHMJ Vol47 no1_contents_S.pdf

 

[lv2dive]

Five years ago-ish? I think John's experience with AG (re RD) was in a UTD class, not a GUE class (I just asked for confirmation) - so I wouldn't yet conclude that GUE has in fact changed their stance on anything. Regardless it would definitely be interesting to get perspective from some people who took GUE tech classes ten or fifteen years ago.

Since (apparently) GUE has changed their stance on this over the years, posts like this would probably be a little more helpful if they stated when they did the GUE training they are talking about.

 

[stuartv]

It's important to note that Ratio Deco as taught by GUE is different that the coathook abortion that UTD calls Ratio Deco. It doesn't surprise me that it has been demonstrated to be entirely incorrect.

The actual ascent plan for the RD divers was shown in the longer video that Kevrumbo posted. Can you post what the GUE RD ascent would be for that same dive? I'm curious how they compare.

Actually, here is the UTD RD ascent, with one error:

Then the UTD profile:
View attachment 402765

The video shows the UTD ascent to have a final stop at 3m for 6:00, on O2.

I'd love to see what the GUE RD ascent would be. That is for 25:00 @ 50m, using 18/45, 50%, and O2.

 

[kensuf]

This is quite the opposite of the Ratio Deco class I took from Andrew. When we worked out a deco profile using ratio Deco, another UTD instructor in the room would do the same profile using one of several different commercial deco software programs. They never matched. According to Andrew, that showed why you should never use a commercial deco software program. Since RD is perfect, the fact that it never matched a commercial program showed that all those programs were defective.

[video]

 

[scubadada]

Thank you. One follow up question. He's talking about the "immune system" response as being one of the crucial factors in DCS.

Over the last years I've personally become more and more skeptical regarding what the DIR people say about deco theory or ascent strategies. He appears to be saying that bubble lead to an immune response and that the immune response leads to DCS. I've always been told (and believe) that bubbles are a problem in and of themselves because they can get lodged in the blood vessels and generally disrupt bloodflow.

My question is, is there something important about the immune system response that we need to remember as tech divers or is this just more smoke being blown up the proverbial back end?

R..

You can find references on vascular inflammation and decompression sickness on PubMed, or even Google

 

[PfcAJ]

The actual ascent plan for the RD divers was shown in the longer video that Kevrumbo posted. Can you post what the GUE RD ascent would be for that same dive? I'm curious how they compare.

Actually, here is the UTD RD ascent, with one error:



The video shows the UTD ascent to have a final stop at 3m for 6:00, on O2.

I'd love to see what the GUE RD ascent would be. That is for 25:00 @ 50m, using 18/45, 50%, and O2.

I'll take a stab at it.

1:1 at 150, add 5mins of deco for every 10ft (70m=165ft, round deeper), so roughly 35mins of deco. Splitsies on 100% and 50%, difference goes shallow. 15mins on 50% (3min stops) then 20mins on oxygen.

The old guideline was (maybe still is, I dont know) to start 1min stops at 75@avg depth. That would start you at 130' for this profile which is pretty deep imo.

 

[lv2dive]

AJ - just off the top of my head - I was thinking this was a tech1 profile, what do you think? I don't have time to run the numbers, if one introduced o2 into the mix, wouldn't it reduce the deco time?