SPGs on CCRs

[JohnnyC]

None if I’m diving standard 3L type configuration. They get checked and analyzed so really no need during the dive. If something happens during the dive I’m probably bailing out anyway so it’s kind of a moot point.

One on the left hip d-ring if I’m diving back gas bailout because it’s my bailout as well as dil so I want to make sure I’ve got gas. It’s similar to the way the GUE’s run their JJ’s.

Bailouts have SPG’s.

 

[stuartv]

I'm still new, so I'm still diving my unit the way it came and I was trained. 2 SPGs, over the shoulders to my front.

I have the transmitters to go on my rEvo, but I have not put them on. My plan is to replace my Predator monitor with a NERD2. When I do that, I will decide about putting the transmitters on then.

My checklists include checking cylinder pressures, and I generally do my pre-jump check after I don the unit, so no button gauges for me.

Unfortunately for me, I looked at my rEvo and I don't think there is room for my transmitters to go directly into the 1st stages. Which means if I use them, I think I will have to put them each on a HP hose - which defeats a significant part of the purpose (to me).

I generally try to stick to the philosophy of "do it the way I was trained until such time as I think I have enough experience to change something for a reason (of my own)." So, I will keep my rig like it is for now (versus putting the transmitters on and wearing one of my Terics in addition to my 2 Predators). When I get a NERD, then I will assess and decide. Hopefully, I'll get the NERD reasonably soon. Which probably means I will not feel ready to make the change to AI yet. It seems plausible that, at that point, my experience may be enough that my comfort level has increased and I longer check my SPGs often enough to bother changing them over to AI.

If I could eliminate the 2 HP hoses, then I think it would be a no-brainer for me. But....

I feel like I'm blathering. Sorry...

 

[Superlyte27]

I admit to being a fairly new CCR (O2ptima) diver, so I am pretty much diving how I was trained. SPGs on both onboard bottles, over the shoulder bungeed just next to the SMCLs. I have SPGs on my SM bailout bottles too as these regs can also be used for Open circuit SM.

I have added a Nerd2 and am seriously considering adding transmitters.

You might chalk this up to being a relative rookie, but on a recent cave dive, peacock springs, peanut line jumped to gold line to challenge sink. ....I did a quick check of my O2 & dil half way between the jump and challenge, and noticed I had burned through almost half of my 3L dil. I was grateful to have had plenty of practice switching to offboard dil, so a quick switch and was in plenti good shape to complete the dive as planned.

If I had drained my onboard dil, I could have still bailed to off board, but it was much nicer to head off the issue and not have any additional stress with having to inflate my wing orally. (Or rely on just drysuit etc)

Your DIL usage will get a lot better with time.

 

[doctormike]

My checklists include checking cylinder pressures, and I generally do my pre-jump check after I don the unit, so no button gauges for me.

Yeah, this is also why I wouldn't use button gauges. Stuart brings up a very important point (topic drift alert). I also think that it's important to do the pre-jump check after donning the unit, since something can get dislodged or even rolled off when donning.

 

[rddvet]

The ccr I dive is configured without spgs. Prior to class I was trepidatious about not having them. My instructor pointed out like was here that I’ve got 10 hours of oxygen and if you don’t realize you ran out of your oxygen due to a failure, you’ve got bigger issues. I just check my consumption after the dive with a pressure checker. All my dil is off board and have spgs. One onboard is oxygen one is suit gas. Most dives I use more suit gas than anything else.

 

[doctormike]

The ccr I dive is configured without spgs. Prior to class I was trepidatious about not having them. My instructor pointed out like was here that I’ve got 10 hours of oxygen and if you don’t realize you ran out of your oxygen due to a failure, you’ve got bigger issues. I just check my consumption after the dive with a pressure checker. All my dil is off board and have spgs. One onboard is oxygen one is suit gas. Most dives I use more suit gas than anything else.

Good point. The bottom line is that you need to always know your PO2. Unless your circuit board is frozen (which should be noticeable), if you run out of O2 your PO2 will drop. You should be aware of that long before you get close to hypoxia. If the O2 MAV doesn't do anything, then you are either out of O2, valve is off, or some sort of downstream problem in the first stage or feed line(s). If it's not the valve, then you either plug in offboard O2, bail out, or go to SCR mode, right?

 

[stuartv]

Yeah, this is also why I wouldn't use button gauges. Stuart brings up a very important point (topic drift alert). I also think that it's important to do the pre-jump check after donning the unit, since something can get dislodged or even rolled off when donning.

My biggest fear in contemplating doing the pre-jump before donning is that I will do what I have seen (in my very brief tenure as a CCR pilot so far) someone else do. Do the pre-jump while standing or kneeling next to the unit. Then, because it's a rEvo, which means it has a Constant Mass Flow orifice, think "oh, I'll turn off the O2 for right now, because I'm not putting it on immediately" and then forget to turn it back on because I "already did my pre-jump and it's ready to go."

I try to remember to check that my O2 is on right before I step off the boat, regardless. But, at least with a rEvo, it seems to me that doing the pre-jump before donning the unit is just asking for trouble.

 

[doctormike]

My biggest fear in contemplating doing the pre-jump before donning is that I will do what I have seen (in my very brief tenure as a CCR pilot so far) someone else do. Do the pre-jump while standing or kneeling next to the unit. Then, because it's a rEvo, which means it has a Constant Mass Flow orifice, think "oh, I'll turn off the O2 for right now, because I'm not putting it on immediately" and then forget to turn it back on because I "already did my pre-jump and it's ready to go."

I try to remember to check that my O2 is on right before I step off the boat, regardless. But, at least with a rEvo, it seems to me that doing the pre-jump before donning the unit is just asking for trouble.

Yup. There was an incident a few years ago at our quarry where a guy passed out in knee deep water in front of his teenage daughter because the O2 feed to the solenoid came loose (yeah, he should have watched his PO2). Easy to do something like that while donning.

And that's the main reason for doing the pre-breathe just before you splash, as Dr. Simon taught us. Not so much for checking your scrubber.

 

[taimen]

Visible pressure readings for dil and o2 are an awareness tool. They (may) give you some time to react to unusually high gas consumption before you end up in a real failure mode. As it is usually not necessary to routinely check pressures, having them constantly displayed on your (secondary) PDC screen with low pressure warnings is convenient.
Running out of dil unexpectedly can be very stressful, while connecting to offboard before getting low is routine (and you can still save some gas to fill your wing from dil cylinder).
An electronic pressure sensor on O2 warns you of accidentally closed valve way before pO2 starts to drop.
Dives with sawtooth profiles or multiple dives between fills benefit from online gas monitoring.
For a beginner monitoring and logging gas consumptions is actually a good learning tool to identify and analyze problems in technique or stress level.
That is how I see the pros. The cons are added complexity in the unit.
I was encouraged to fit pressure sensors by my instructor and been happy with them. All the problem solving procedures doctormike has repeated in this thread were still part of the training.

 

[KenGordon]

I like simple things like hitting my MAV buttons and checking my valves are on and I still briefly look at my SPGs before I splash. Perhaps it's an old OC habit but I still like doing it.

I like this idea. My SPGs are behind me so I can’t do it and that makes adding the transmitters attractive (except they cost a fortune).

However, what it protects against is having left the unit with the cylinders turned off but the lines still charged. So...

What do people generally do between dives regarding turning off and purging? The risk being just turning off and then not turning on again. You put it back on, breath it for a while and it maintains 0.7 for long enough to fool you, you jump in the water, don’t look at the handset for a bit and go hypoxic swimming to the shot line.

As regards SPGs on bailout. I have SPGs on mine, mostly because they are my OC deco cylinders and regs, but also because I expect to want to know exactly how bad my breathing rate is so as to moderate, or not, my ascent if I have a CO2 hit. It can also be reassuring to someone you hand the cylinder off to if they can see it is nice and full.