Rebreathers (CCR) What Recreational divers need to know

[Scott]

There is nothing officially taught about rebreathers in a rescue class, and I would bet 90% of rescue instructors would not have a clue what to teach if they decided it needed to be added on its own.

It has been a couple years or more but PADI was making the rounds conducting workshops for rescuing CCR divers as well as sidemount.
The PADI rep during our workshop said they would be adding chapters to the next update of the course but we all know how long that could take.
PADI recruited local CCR and sidemount divers to help conduct the workshop. I was volunteered for the sidemount portion and we had a guy in doubles for additional grins and giggles.

This is a good topic. To instructors teaching Rescue, I would suggest reaching out to CCR, SM and even BM divers in your area to help conduct this as part of a course.
Because it is becoming more and more common to have mixed teams.

 

[KenGordon]

Some more common bailout valves:

Poseidon. Black lever on the left of the pic is up for CCR and forward for OC
View attachment 423390

Hollis BOV. Silver lever is currently in CCR position IIRC

View attachment 423389

Some aftermarket BOV look like this, twist the top black switch to change setting

View attachment 423388

CCR diver with bailout cylinder on their left

View attachment 423392

Typical bailout cylinder rigging:

View attachment 423391

This has only 1 second stage, the idea being that there is only 1 failure being planned for, i.e. if my CCR goes bang, Im using it and we are getting out. If you run OOG then you use it and we get out. When I am diving mixed team, especially with newer divers, I will put 2 second stages on the bailout just in case.

Please note that not all rebreathers have a bailout valve. Often the diver must switch to a normal OC regulator. In that case the valve attached to the loop is a DSV and if you change the lever position you are putting it in SURFACE MODE so the CCR driver will inhale water.

Rescuing a CCR diver is properly hard. The chances of a random OW diver doing it are about zero. The chances of a fully trained up CCR diver who last trained on it a year ago are maybe 50%.

I explain where to take gas, the red lights, how to give me dil, how that will change buoyancy and where the counter lung dump is. I also warn about closing the loop.

The BSAC second level OC course covers rebreathers in general terms, secondary take works for RB divers supplying gas and there are restrictions against diving mixed teams of Ocean Diver (first level course, OW equivalent). It is explicitly the responsibility of a diver with 'advanced' configurations to explain it to their buddy. In the UK conditions and diving 'style' are such that you will only really be concerned with your buddy wrt OOG situations.

I always have a second stage on my bailout, even with a bailout valve directly running from the cylinder. This is because the mouthpiece/valve can fail - various O rings and the mouthpiece itself can fail. This means that there is always a regulator for an OOG diver to take.

I do come across some CCR divers who rely on only a BOV fed from the 3l dil cylinder for shallow no-deco dives. Do not choose one as a buddy.

 

[Gareth J]

This has been a good thread.

A lot of good information has been provided.

Even as a long time CCR diver, I am not familiar with all units. I would make a point of asking during the briefing.

1. How do I close the mouth piece.
2. Do you have a BOV (as Ken said not all units do), if so, how do I switch it to OC.
3. How do I flush your loop. (Flushing the loop puts clean gas in the breathing loop. This solves low O2, high O2, and CO2 issues - at least in the relative short term.)


Generally. I very, very seldom dive with any diver who is diving on a single cylinder. If my buddy isn't on CCR, then they are normally diving a twinset. Or as an absolute minimum a single cylinder with a pony (or stage). This means that we both are 'self sufficient' at least we can each bailout onto alternate gas initially. How we handle the issue from there is another matter. Under these kind of circumstances we will only be thinking about our exit strategy, even if that includes stops.

Gareth

 

[bowlofpetunias]

I am also not trying to be difficult and I am probably not expressing myself very well.

Here's the problem, the things you've mentioned are based on assumptions, and each of them has issues.

1) Maybe, maybe not. What if it's deep bailout and sharing will put you to sleep? What if he doesn't have anything slung but he's diving an SCR with a long hose. You may not see any slung tanks, but it doesn't mean he can't share air.

This isnt too far off what you are saying
If I see a CCR diver with a slung cylinder.. I know he has a chance of sharing air.. If he doesn't i will assume no

2) What if the red light you see is on their HUD? Red light doesn't mean bad. What if you can't get his attention because he's focused on some other task? (which leads into 3

If I see red lights flashing.. I will try to point it out to him.
If he is clearly focusing on something or doing something of course I would watch and at what seemed an appropriate time get his attention. This means some interaction if needed. Use of my light OK signal in front of his field of vision or a physical tap. If he responds to that I can point to whatever is bothering me and signal OK. His response determines next step. I would never interfere with ANY diver's gear without their consent or clear evidence they could not do anything for themselves!

[/QUOTE]3) Just because he doesn't respond doesn't mean you should throw the lever. Unless you know for sure beforehand, you could cause some issues.[/QUOTE]
If he doesn't respond I will look for a bail out lever or button like in the picture
See above about response. I agree it is downright dangerous to muck around with stuff you don't know about. Perhaps the best next best option is to look to see if he has a buddy who would hopefully know his rig?

[/QUOTE]4) What if he's bailed out and you're only seeing him in the middle of switching to a second stage? Sure, he shouldn't have the loop out of his mouth until he's got another viable air source already in hand and ready to go, but people to goofy stuff all the time.[/QUOTE]
I need to keep the mouthpiece in place so his loop doesn't fill
If the diver appears to be in the process of some action I would not interfere with it. I don't know enough to conclude that what he is doing is wrong. I also don't know enough about putting the mouthpiece back if it is out. I would assume if I found an unresponsive CCR diver with nothing in his mouth that the loop has flooded and would be useless. My inclination would be to try to get my octo into him if possible butI suspect in this situation there really wouldn't be much I could do for him anyway.

5) That's not a bad idea, but grabbing a CC diver and swimming up without double checking all the other things first could be quite disastrous if you're not fully capable of controlling the situation during ascent.

If I can get him to the surface while doing that great if not I get help
I can only do what I can do and I hope non of this is ever needed
Absolutely agree here which is why I said If I can

[/QUOTE]6) The best way to deal with this is to talk with the diver beforehand and get a solid idea of his/her wants/needs and how to go about accomplishing those. Trying to make a checklist for diving with a CC buddy is doomed to fail because each situation is very individual, and dependent on several other things.

I don't want you to think I'm being purposely argumentative, I just wanted to point out some flaws in your train of thought. Because each situation "depends" as stuartv says, you can't just go with a set of rules and assume it's the right choice. The right choice will be very situationally dependent and really the only "rule" you should have is "talk to your buddy beforehand and make sure you both understand the plan.[/QUOTE]

We are in total agreement here. The problem I am concerned about is the CCR diver who is not necessarily my buddy or my team mate where we wouldn't have had a chance to talk or even seen each other prior to underwater contact.

ETA: I think scubadada's rebreather experience is HUGELY advantageous for an OC diver to partake in simply because many of the things covered in an experience like that will directly impact your ability to dive with a CCR diver. Even understanding the basic concepts of rebreather function and physiology will go a long way to expanding your mental toolbox in the event you're in a situation where you're diving a mixed team.

Absolutely! We have considered trying to take a rebreather experience. Certainly if we were going to have a buddy who dived CCR that would be one of the necessities in order to be a good buddy.

Please understand I am not trying to be argumentative here either. I am just trying to get a few things straight in my head. I figure other OW divers may have similar questions or ideas and be reluctant to ask or reading the thread later. I really appreciate everyone providing their answers. with the increase of CCR divers in non technical dive sites I think this is an important conversation to have.

 

[bowlofpetunias]

A long time ago Stephen Hawkins (aka Dive Mole) put together a buddy info page for people diving with CCR (AP Inspiration specifically). Seems his website is long gone but Wayback Machine has an archive here

He also produced a 'card' that could be laminated which (hopefully he won't mind) I've attached to this post.

Wonderful thank you. I have copied them. I understand that they are specific to a type of CCR butCCR's do have common components and it also helps with the alphabet soup of terms concept. I will read them later.

 

[doctormike]

A long time ago Stephen Hawkins (aka Dive Mole) put together a buddy info page for people diving with CCR (AP Inspiration specifically). Seems his website is long gone but Wayback Machine has an archive here

He also produced a 'card' that could be laminated which (hopefully he won't mind) I've attached to this post.

This is a really well done piece of literature, very thorough. However, I think that it is WAY too detailed for an OC diver buddies with a CCR diver. It has so much information that it's overwhelming - the OC diver should just be presented with the few things that they need to know to help in an emergency or share gas. There is no need for them to know about positive and negative checks, calibration, etc...

Good point about closing the DSV if the loop is out and the diver is unresponsive, to prevent flooding. We should have listed that one above!

 

[doctormike]

Flushing the loop puts clean gas in the breathing loop. This solves low O2, high O2, and CO2 issues - at least in the relative short term.

With the caveat that this shouldn't be done for a diver with hypoxic dil at or near the surface. But I guess that would be an unlikely buddy pairing...

 

[doctormike]

Here's a good video for the OC divers - it shows a high PO2 alert that the diver missed but was picked up by the camera. It also shows you what bailout looks like. In this case, the problem was that the solenoid was stuck open, continually injecting oxygen into the loop.

 

[bowlofpetunias]

@doctormike that was a fascinating thing to watch. Was I seeing him "feathering" the O2 cylinder at one point?

 

[doctormike]

@doctormike that was a fascinating thing to watch. Was I seeing him "feathering" the O2 cylinder at one point?

Yup! A bit beyond the scope of this discussion, but basically the PO2 spike was caused by O2 being inadvertently and continuously injected into the loop. This can come from two paths - the solenoid (which is an electrically controlled valve that adds O2 automatically when the PO2 drops below the desired setpoint), or the manual addition valve (MAV), which injects O2 when the diver pushes the button.

It's hard to completely reconstruct what happened, but it looks like he wasn't sure what the problem was initially, so he bailed out to open circuit and started the ascent. However, from a deco point of view, it's better if you can get back on the loop, so that you always have an ideal mix for each depth. So what he did was figure out that the problem was that the solenoid was stuck open. He also at one point considered the MAV being stuck open, which I assume is why he disconnected that hose (easy to do).

I have heard that some older CCRs had a quick disconnect for the solenoid feed. So if you determined it was the solenoid stuck open (by hearing it or by seeing the O2 rise after disconnecting the MAV), you could disconnect the solenoid, reconnect the MAV, and just run the unit manually, keeping the PO2 where you wanted it with the push button. Not sure how popular this is any more, since that raises the issue of accidental disconnection. Mine has a threaded LP connector, not something that you can disconnect during a dive.

In this case (since disconnecting the solenoid wasn't an option), he just accepted the fact that the solenoid had failed open, and kept the PO2 where he wanted it by opening and closing the O2 valve - basically using it like the push button on the MAV. The PO2 dropped over time as he metabolized O2 in the loop during deco, so a quick feather of the valve squirts a bit of O2 into the loop, and bumps the PO2 back up to where it should be.