DIR- GUE CCR Fundamentals

[Germie]

Certainly this also seems to be what 100-metre ('Mod3'), and perhaps even some 60-metre ('Mod2') divers are doing under other training regimes.

Is GUE CCR 1.0 even at 30 metres?

You always need to have a PO2 of the diluent lower than 1.3 to flush, to bring a PO2 down when needed. That is not special to gue. Remember other agencies already teached ccr long time before gue adopted a ccr. And all the bailout/problem solve strategies are teached by all agencies, even the ones that do recreational ccr (that is another discussion if it is a good idea to let an ow diver dive ccr, but the strategy for all problems is then: bo)

 

[crofrog]

This is confirmed. The latest round of GUE standards changes doesn't include approval of any other CCR models. The JJ-CCR remains the only approved option. (They do still have the PSCR course listed if someone wants to learn the Halcyon RB80.)

Where is the list of "approved" car's contained, because the standards don't specify the JJ?

 

[ginti]

- 30m max, MDL dives only (although - is that OC MDL or CC MDL? You could do a much longer dive @ 24m or 21m with a CCR than on 32)

Why would it be OC? Are you speaking of specific scenarios, like OC divers going with CCR1 ones, or in general?

 

[whynot]

Since I posted the following in a chat group on another platform, I'll place it here as well - albeit with some minor modifications:

I do wish that CCR-F included an expiry component analogous to (IIRC) that of the old NSS-CDS Apprentice Cave Diver course; i.e., a CCR-F diver has x amount of time to pursue CCR-T1 before their CCR-F certification goes

. I say this because CCR-F is not designed to be a final end-point and because outside of training/experience-building, recreational CCR diving is contrary to the ethos of GUE (and DIR) diving. That said, there will always be divers who deviate from their training. I also recognize and appreciate that GUE communities, my own and at large, do a good job of dealing with such divers via coaching and “you must go - be gone now!” when necessary.

 

[johnkendall]

View attachment 874293

Where is the list of "approved" car's contained, because the standards don't specify the JJ?

The current list of approved CCRs is:

JJCCR

HTH
John

 

[justinthedeeps]

You always need to have a PO2 of the diluent lower than 1.3 to flush, to bring a PO2 down when needed. That is not special to gue. Remember other agencies already teached ccr long time before gue adopted a ccr. And all the bailout/problem solve strategies are teached by all agencies, even the ones that do recreational ccr (that is another discussion if it is a good idea to let an ow diver dive ccr, but the strategy for all problems is then: bo)

Agreed, yes 30 metres air dil or 21/35 is a nice low diluent ppO2, I get 0.84 for that (4 * 0.21)
The GUE table might be typoed--1.05 would be for 40 metres on air or 21/35, not 30 metres--but still acceptable either way

[I think we got sidetracked into diluent ppO2 a bit, I was talking about setpoints when it came to MDL/NDL discussion]

Using a diluent with only 18% oxygen in it for 45 metre dives stays ultra true to diluent 1.0 principle, and being 'normoxic' has few drawbacks. Slightly different from other agencies who readily put divers on a mix with ~20-21% of oxygen in it (a still useful diluent ppO2 of 1.1)

45% helium for a 45 metre dive is more different

I would expect to see some differences in prescribed deco (and NDL/MDL) by Shearwater computers (with matched GF etc) when diving air, 20/20 or 20/35 diluent (TDI etc), versus an 18/45 diluent (GUE table) for 45 metre dives.

Do we believe in the extra deco that Shearwater might assign for 45% vs 35%? This post keeps coming up

What is the rationale to carry an 18/45 dilout for 45 metres, versus 18/35?
18/35 achieves diluent @1.0, an END of ~25 metres and a gas density of ~5g/L at 45m
18/45 @45 metres is meant to give an END of ~20 metres and 4.4 g/L?

But note these ENDs assume oxygen is narcotic, which is unproven.

If only nitrogen is narcotic, the END of 18/35 @45 metres is more like ~20m, and ~15m for 18/45.

Note if oxygen is not narcotic, then a switch from air to 40% nitrox (ppO2=1.6) at 30 metres should result in a decrease in narcosis (if it was blended from pure ABO/medical-grade oxygen with no argon), or similarly a 21-metre air 'narc' should disappear upon switching to 50% nitrox. I'm not sure if I have noticed that kind of effect, but it could be fairly subtle at these depths/pressures. There is some study suggesting it happened with cleanly-blended EAN32 vs. air though.