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.

 

[Heat Miser]

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?

Yes I worked out a while back there is a big difference between GUE teaching END/Densities/PPo2 and other Agencies/Teck Instructors. I think they make a trade off of doing more deco and having higher Surf GF.

Post in thread 'GUE Fundamentals'

Jan 20, 2022

It was before I was using a rebreather otherwise I should have used 18/45.

View attachment 701703

I haven't seen that before but its conservative, compared to the Gas densities, DI pO2, and ENDS I would target on the revo and reflect your 1.2 setpoint and higher He content. *Not that I have ever dived deeper than 60m.

I was taught to target 5.2 gr/l gas density, dil ppO2 1.1, END of 20-25m off a higher in loop setpoint 1.3

These are yours based off standard gases

But I can see why you were mentioning carrying Deco stages on shallow CCR dives, because of the onboard...

• Heat Miser

I haven't seen that before but its conservative, compared to the Gas densities, DI pO2, and ENDS I would target on the revo and reflect your 1.2 setpoint and higher He content. *Not that I have ever dived deeper than 60m.

I was taught to target 5.2 gr/l gas density, dil ppO2 1.1, END of 20-25m off a higher in loop setpoint 1.3

These are yours based off standard gases
View attachment 701715
But I can see why you were mentioning carrying Deco stages on shallow CCR dives, because of the onboard bailout in the D7 at a dil pO2 o 1,0 you start racking up up deco penalty a bit faster than someone with offboard bailout and higher O2 content

Interesting I thought all thing GUE were better MAYBE I'll have to think a bit about it..

 

[Nick_Radov]

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.

Is that really still true? I haven't seen any official statements from GUE on that point. I think there is perhaps a case for underwater photographers who want to use a CCR for recreational profiles due to fewer bubbles but have no interest in tech diving.

 

[ChrisMBC]

Is that really still true? I haven't seen any official statements from GUE on that point. I think there is perhaps a case for underwater photographers who want to use a CCR for recreational profiles due to fewer bubbles but have no interest in tech diving.

From the CCR-F workbook:

 

[Germie]

Yes I worked out a while back there is a big difference between GUE teaching END/Densities/PPo2 and other Agencies/Teck Instructors. I think they make a trade off of doing more deco and having higher Surf GF.

Post in thread 'GUE Fundamentals'

Jan 20, 2022

It was before I was using a rebreather otherwise I should have used 18/45.

View attachment 701703

I haven't seen that before but its conservative, compared to the Gas densities, DI pO2, and ENDS I would target on the revo and reflect your 1.2 setpoint and higher He content. *Not that I have ever dived deeper than 60m.

I was taught to target 5.2 gr/l gas density, dil ppO2 1.1, END of 20-25m off a higher in loop setpoint 1.3

These are yours based off standard gases

But I can see why you were mentioning carrying Deco stages on shallow CCR dives, because of the onboard...

• Heat Miser

The 18/45 vs 18/35 discussion has in my opinion nothing to do with safer. Nor oc, nor CCR. At 45m the difference in END is marginal. And really within the max END of 30m.
But also at 50-55m there is no reason why 18/35 does not work within the limit of max 30m. And on oc you save a lot of money on helium nowadays, haha.

The only thing is the blending. And if you come from deeper than 55-60m, there can be a reason to choose for an 18/45 as bo.

My diluents always start with a 6/72, also a standardgas called a poormansmix (and 12/65 also is a standardgas, haha). And then I do a topup with air, analyse, and probable I will still have a gas that is usable for a dive I want to do in the future. I have more than 1 diluent cylinder, so if someone asks me to do a 100m+ dive next week, I don't need to run to a fillingstation, I have the gases ready. The used diluents are topupped, get a new label and if someone asks me for a 60 or 70m dive, I will have diluents ready. And after a 3rd topup I probably have a 40-45 m gas left and otherwise I will use it in shallows.
This means that on a 55m dive I will have a different diluent than some that just filled it for that dive. But that is no problem. And if I use a 20/13 at 35m, I still will not die because of my diluent. Haha.

Gradient factors shallow than 40m are in my opinion not that important, only very small differences if you dive in open water. But if an instructor will tell me I have to dive on 20/85 on a wreckdive to 60m, it will get a middle finger or at least there will be a discussion following. I will stick with my 40/75 or 40/70 and can discuss a gf low in the range from 40-50, but I will stick with my 75 as gf high and can explain why. But if you plan, and even gue does nowadays following a plan instead of deco by head, this is not a problem.

An expiring ccr fundies cert is not an good idea I think. Not everybody who does a basic ccr course wants to do technical diving. I know a few photographers who own a ccr (inspiration in all cases), and use it for the reason of the 'no bubbles'. I see a ccr fundies as a mod1 course from other agencies. In some agencies you can do directly some deco at mod1, but with a recreational ccr course not.

But even if you don't renew a gue card after 2 years, and you want to renew it after 4 years, it is just paying. I friend of mine had that a few years ago with a C1 cert and we already did dives over C2 level on CCR. He then wanted to do the full cave part and renewed it. At the end ended with a ccr cave cert from another agency as he did not have a gue ccr and gue was not teaching ccr cave at that moment. So at the end it is all about the money and I prefer then certs that don't expire at all, so I cannot forget to renew them. Also renewing them will cost me a lot of money if I have to do that with all that (partly useless) cards, haha.
This remembers me that I also have to renew my DAN insurance, haha.