UTD Decompression profile study results published

[PfcAJ]

Discussions like this make me want to take utd classes. Seems like there could be a lot of value to learning and practicing their methods.

 

[Kevrumbo]

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) . . .
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?

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 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.

Rick

(Refer to link below).

The 3m O2 stop for 6min: all that is essentially is just a moving ascent of 6 minutes to go from 6m to the surface on O2 at a very slow rate of 1meter per min (1mpm).

The reason for the switch to 18/45 from 50% Nitrox at 9m for 4 minutes is simply a backgas break from the high ppO2 of the Nitrox 50 deco stops, and to stow the Nitrox50 regulator & deco bottle, and to bring up & prep the O2 deco bottle for the switch upon reaching 6m.

Ratio Deco Profile Schedules

 

[Remy B.]

Kevin where did it change or why there are two profiles now ?

You posted this first

@50m for 25min bottom time on 18/45 standard gas and two deco gases Eanx50 and O2, GUE has 15min with 50% and 15min with 100% O2, while UTD has 17.5min on 50% and 17.5min on 100% O2 -or nearly the same Eanx50 and O2 time schedules for both versions of Ratio Deco.

Depth: GUE: UTD:
21m, 3min, 3.5min [Eanx50]
18m, 3min, 3.5min;
15m, 3min, 3.5min;
12m, 3min, 3.5min;
9m, 3min, 3.5min;
6m, 15min, 17.5min [Oxygen]
Or optionally:
6m, 9min, 11.5min [Oxygen]
---->, 6min, 6min [---> a surfacing ascent rate from 6m at 1 meter per minute].


and this one later

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).

 

[Kevrumbo]

Kevin where did it change or why there are two profiles now ?

You posted this first

@50m for 25min bottom time on 18/45 standard gas and two deco gases Eanx50 and O2, GUE has 15min with 50% and 15min with 100% O2, while UTD has 17.5min on 50% and 17.5min on 100% O2 -or nearly the same Eanx50 and O2 time schedules for both versions of Ratio Deco.

Depth: GUE: UTD:
21m, 3min, 3.5min [Eanx50]
18m, 3min, 3.5min;
15m, 3min, 3.5min;
12m, 3min, 3.5min;
9m, 3min, 3.5min;
6m, 15min, 17.5min [Oxygen]
Or optionally:
6m, 9min, 11.5min [Oxygen]
---->, 6min, 6min [---> a surfacing ascent rate from 6m at 1 meter per minute].


and this one later

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).

GUE's version uses slowing ascent rates from the bottom to the first deco gas switch depth, unlike UTD's discrete hard deepstops at 75% and 50% max depth. That being said. . .

Ratio 1:1 or 1:2 both prescribes 35min total time needed on Nitrox50 from 21m to the surface, for a 25min bottom time at 50m depth using 18/45 mix; half of this 35min time (17.5min) is over 5 stops from 21m to 9m, so each of the 5 stops is 3.5min long; the other 17.5min is the deco time at 6m on Nitrox50 or optionally Oxygen.

@PfcAJ posted a similar RD profile of 15min for the 5 stops from 21m to 9m (3,3,3,3,3), and re-distributed the extra 2.5min to the 6m stop for 17.5 plus 2.5 equals 20min at 6m.

@huwporter posted a just as easy to remember profile of 15min from 21m to 9m (3,3,3,3,3); and 15min at 6m (and assuming a 1meter per min ascent rate from 6m to the surface).

You can also re-distribute the time as 17min from 21m to 9m (4,3,3,3,4) and 18min at 6m as well, and this is the revised GUE profile for the same 35min total surfacing time that you see above. . .

 

[Remy B.]

Why not redistributing those 3-4min UTD/GUE deeper times and add them to your 12m and 9m stops ? like the stair/ pyramid strategy that I mention, something negative with that ? while keeping the deeper stops @1 min duration, it seems more simpler to remember and emulates more what the NEDU studies show that emphasizing deeper stops is not good idea.

 

[Kevrumbo]

Why not redistributing those 3-4min UTD/GUE deeper times and add them to your 12m and 9m stops ? like the stair/ pyramid strategy that I mention, something negative with that ? while keeping the deeper stops @1 min duration, it seems more simpler to remember and emulates more what the NEDU studies show that emphasizing deeper stops is not good idea.

I don't know what is so difficult to remember short Deco profiles, another way to do it is a stair calculation you just have to remember where your 1st stop starts with GF and what is the amount of time at 6m, by knowing the total time @ 6m you know that the one at 9m is half of that and that the one of 12m is the half of the one @ 9m, and with short profiles everybody knows that at 21m with 50% most of the time you start with 2min then to go back to 1min

if your first stop starts at 28m you stop for 1min
25m @ 1min
21m @ 2min switch to 50%
18m @ 1min
15m @ 1min
12m @ 5min
9m @ 9min
6m @ 17min

that stair profile is closer to a GF than a RD that on-gasses unnecessarily deeper.

. . .

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).

 

[elgoog]

Discussions like this make me want to take utd classes. Seems like there could be a lot of value to learning and practicing their methods.

Wait for it .....

 

[PfcAJ]

Wait for it .....

AHAHAHAAH APRIL FOOLS!!!!!!!!

I was beginning to think no one noticed or I'll have to be more subtle next year.

 

[Ayisha]

Nah, it was too obvious. We were wondering how long you would keep that going.

 

[decompression]

I was gonna pay for AJ's course.......