UTD Decompression profile study results published

[huwporter]

I couldn't find the utd rd profile published, but from reading this thread I was under the impression the 9m stop was on 18/45 backgas rather than 50% nitrox.

That is correct. It's in the video posted on page 2.

 

[Ayisha]

When I did Tech1 last year there was no RD. There was pragmatic deco.They did change the name.

It would be helpful if everyone calls it pragmatic deco to avoid confusion. It's interesting that the new name came out on the 146th post in this thread, unless I missed it previously.

I did Fundies a few years ago, and of course we didn't learn ratio deco/pragmatic deco since we only do minimum deco. I had thought ratio deco in GUE was long gone until I started to hear references to it in the last year or so.

 

[KenGordon]

Just for the fun of it (and to complicate matters), I ran the UTD RD profile through the Subsurface dive planner: View attachment 403407

Turns out, with GFs set to 30/80 this ascent is ok (as in: never violates the ceiling).But only barely: If you lower GFhigh by a bit or slightly mess with the timing of the first gas switch to EAN50 you violate the ceiling in the final ascent. So, from the point of view of Bühlmann with GF, you would not expect any more DCS symptoms as if you let GF 30/80 directly compute your ascent.

For comparison, here is the latter plan (note well the different time scales on the time axis!):
View attachment 403408

This is a very interesting post. Did you include the extra backgas when shallow part?

So (assuming it includes the shallow backgas - I can't read the graphs well enough to tell) you can take a disadvantageous profile (the UTD) one and still dive it within some given settings on a computer by going more slowly in places. But if really following a profile generated by the same settings, and sticking to the plan, the outcome is better.

So when actually in the water, flying the computer, these two profiles might seem to be equivalent, each being ok with GF 30/80. Oops.

@atdotde - when the heat graphs are on, perhaps the graph ought to optionally include significant surface offgassing.

Edit: ok, I looked harder at the graphs above and the UTD profile and they don't match. 4 minutes less 50% in the UTD one so I can't support my point above.

BTW, does anyone know why there is a 3m O2 stop? Is there some extra voodoo I am unaware of?

 

[Kevrumbo]

Summary of deco schedules, for 25min at 50m with 18/45 bottom gas and Nitrox50 & O2:

Ratio Deco Methods:

UTD:
50m, 25min;
(ascent rate 9m/min);
36m, 1min (75% deepstop);
33m, 1min;
30m, 1min;
27m, 1min;
24m, 3min; (50% deepstop);
21m, 5min (Nitrox50 w/ S-curve);
18m, 5min;
15m, 2min;
12m, 2min;
9m, 4min (switch to backgas and stow Nitrox50 regulator & bottle);
6m, 12min (O2);
3m, 6min.

GUE:
50m, 25min;
(ascent rate 9m/min to 36m);
36m, 0.5min;
(ascent rate 3m/min to 24m);
24m, 1min;
21m, 4min (Nitrox 50);
18m, 3min;
15m, 3min;
12m, 3min;
9m, 4min;
6m, 18min (if brought, switch to O2 -otherwise continue Nitrox50).

Buhlmann ZHL-16B 30/80 (from Deco Planner 3.1.4):
50m, 25min
(ascent rate 9m/min);
27m, 1min;
24m, 1min;
21m, 1min (Nitrox50);
18m, 1min;
15m, 2min;
12m, 3min;
9m, 5min;
6m, 16min (O2);

Buhlmann ZHL-16B 50/80 (from Deco Planner 3.1.4):
50m, 25min;
(ascent rate 9m/min);
21m, 1min (Nitrox50);
18m, 1min;
15m, 2min;
12m, 2min;
9m, 5min;
6m, 16min (O2).

 

[huwporter]

More incorrect stuff

Kev, any chance you could not post incorrect stuff over and over? A) you've already been told that your copy of GUE SOPs is out of date, and B) you can't even read your out of date copy properly.

 

[Kevrumbo]

Kev, any chance you could not post incorrect stuff over and over? A) you've already been told that your copy of GUE SOPs is out of date, and B) you can't even read your out of date copy properly.

Then contribute to the discussion and post an up-to-date profile reflecting current GUE SOP.

You savvy mate?

 

[huwporter]

Then contribute to the discussion and post an up-to-date profile reflecting current GUE SOP.

You savvy mate?

I did.

 

[Kevrumbo]

I did.

Can everyone please note that these are NOT the current GUE SOPs.

Kev, any chance you could not post incorrect stuff over and over? A) you've already been told that your copy of GUE SOPs is out of date, and B) you can't even read your out of date copy properly.

And the latest revised GUE standard operating procedure ascent rates from the bottom to the first intermediate deco gas switch are. . .?

Copy and paste what you think a representative edited, corrected & updated GUE Ratio Deco ("pragmatic deco") profile should be to the Summary above mate. . .

 

[barth]

2 computers - buy 2 computers. Use 1 to tell you your ascent. If it breaks, use the other one to complete your ascent. If they both break, follow your buddy.

Ratio Deco - buy 2 bottom timer devices. Use your brain and 1 bottom timer to tell you your ascent. If the BT breaks, use the other to complete your ascent. If they both break, follow your buddy.

Which one is "simple"?

For the RD proponents, if they dive with at least one of their 2 BT devices being a completely mechanical device that tells them time and depth, then I can accept and respect their protocol. But, anyone who says "I can't depend on a computer because it's an electronic device" and then dives with 2 electronic bottom timers, well, I feel like they have really drunk the Kool-Aid. ESPECIALLY if they are using one of those electronic devices to tell them their average depth (a value the BT CALCULATES) and then calculating their ascent based on that.

There was one post that almost made some sense to me. The poster said they were cheap and didn't want to spend $2K on computers. I can certainly understand that. But, you can buy a brand new DR Nitek Q for $400 that is a multi-gas trimix computer. So, for $800, you can do whatever tech diving you want, with 2 fully capable computers. If you can't afford the difference between 2 bottom timers and 2 DR Niteks, then, really, you probably can't afford to go tech diving anyway.

I think RD (in the form I understand GUE to employ it) is cool. Doing your dive plan and having an idea of what the ratio of deco time to bottom time is certainly can't hurt. Being able to apply that knowledge to sanity check the ascent calculated by your dive computer is nice.

But, I think the NEED for it anymore is pretty much like the NEED for OW students to learn how to use tables. I.e. the notion that it is NEEDED is simply outdated.

I just use 1 bottomtimer. My bottomtimer had never failed. If it will fail my buddy his/her bottomtimer is backup.

For planning I use software at my laptop or iPhone. Pragmatic deco is also in my wetnotes.

For tech dives in openwater there is no benefit for me for using a computer. There should be a diveplan before the dive starts. In the team we are using the same gas(ses). We have to know minimum gas in doubles and we should have enough decogas. It is nice to have a decoplan. That's much better for me then wait at every stop until everybody's computer says we can go to the next stop. Maybe we can do a few minutes less deco sometimes when we were using a computer. But that's just a few minutes, if it is much more we shorten the deco. But even when you are using a computer, you maybe can do a few mimutes less deco, you have to wait for your buddys computer(s).

A computer / bottomtimer is just a tool for diving for me. When I would use a computer the dive looks almost the same I think. Most of the time minimum gas in doubles makes the dive ending. Deco would almost be the same with a computer/bottomtimer for me. The decoplanning with software on my latop or smartphone would not be (very) different than when I would use a divecomputer.

My bottomtimer is actually a divecomputer, but it is always in gauge mode...

 

[Kevrumbo]

I just use 1 bottomtimer. My bottomtimer had never failed. If it will fail my buddy his/her bottomtimer is backup.

For planning I use software at my laptop or iPhone. Pragmatic deco is also in my wetnotes.

For tech dives in openwater there is no benefit for me for using a computer. There should be a diveplan before the dive starts. In the team we are using the same gas(ses). We have to know minimum gas in doubles and we should have enough decogas. It is nice to have a decoplan. That's much better for me then wait at every stop until everybody's computer says we can go to the next stop. Maybe we can do a few minutes less deco sometimes when we were using a computer. But that's just a few minutes, if it is much more we shorten the deco. But even when you are using a computer, you maybe can do a few mimutes less deco, you have to wait for your buddys computer(s).

A computer / bottomtimer is just a tool for diving for me. When I would use a computer the dive looks almost the same I think. Most of the time minimum gas in doubles makes the dive ending. Deco would almost be the same with a computer/bottomtimer for me. The decoplanning with software on my latop or smartphone would not be (very) different than when I would use a divecomputer.

My bottomtimer is actually a divecomputer, but it is always in gauge mode...

By repetition, diving the same deco profiles over time and experience, you learn to memorize & understand an entire deco schedule by rote using only the bottom timer as depth, run time & elapsed time reference. But always have a range of contingency deco profiles written out as back-up reference in your wetnotes (profiles for deeper or longer than expected depths or bottom time for example).