Rebreathers (CCR) What Recreational divers need to know

[bowlofpetunias]

This comes across as you having an intent to demand (if necessary) a briefing on someone's CCR unit. Unless that person is going to be your actual dive buddy, I am unclear on why you feel as though you would have the right to insist on such a thing.

I seriously don't understand how you cam to that conclusion from my post.. It is common here to have a smallish group dive together where there may or may not be vocalized buddy pairs. We dive as a group and watch everyone in the group. It works well believe it or not. We all check for everyone very regularly and if we don't see someone we check to make sure someone else knows where they are. In the case I referred to the CCR was with us in a group of 4. In that situation we should have all had a briefing and nobody did. I am normally the one who reminds people to do the checks.

I certainly wouldn't go to someone and demand a briefing if they were not diving with me or my group! If they didn't look busy and I had the time I might approach pretty well anyone and engage in a friendly chat.

I think somewhere along the line the OP muddied the waters (and not unreasonably) by moving away from "being buddied with a CCR diver" and moving to "there's a CCR diver in the same water" which is SUBSTANTIALLY different and opens up the gigantic can of worms we're all guilty of adding to. A good case in point was her list. It's not that there was anything wrong with it, but there's a lot of assumption behind it. Even my own preferences in the situation run contrary to my recommendations to others because my situation is different from everyone else's. And there are times where my situation will run exactly to my recommendations, as it is situational and as is any CCR diver diving in a mixed team.

Umm No... in my OP I did mention what if you are buddied with a CCR diver or just happen to come across one in trouble because they are diving the same sites as OC divers more and more.

Realistically speaking, regardless of anything else, unless the CCR diver is YOUR buddy, the best course of action is to simply pretend they do not exist, since there are so many potential answers to the questions presented here, and what's appropriate in one situation may not be appropriate in the same situation, given even one different variable (think the simple difference between having a BOV or a DSV, even with all else being equal)

I do not have a CCR buddy and in all honesty don't plan to have one. If I see aCCR diver non responsive (as an ex-paramedic I am capable of telling the difference between busy, distracted and unresponsive) I would prefer to have some ideas on what to do or not to do rather than pretend he doesn't exist!

Since it's the basic forum, I think OP needs to concentrate on one issue at a time. In this case, I think she needs to approach it as solely the situation of being buddied with a CCR diver. Everything else should cease to exist until she has reached that point of knowledge and experience to understand the issues and broaden her perspective in other situations.

My goal in this thread was to get CCR divers and OC divers to engage in a conversation that might increase the knowledge to assist each other in an emergency. Perhaps the OP was too broad a question after all. I have no intention of diving with a CCR buddy should that change of course I will do everything I can to know how to deal with them and their specific unit!

I think somewhere along the line the OP muddied the waters (and not unreasonably) by moving away from "being buddied with a CCR diver" and moving to "there's a CCR diver in the same water" which is SUBSTANTIALLY different and opens up the gigantic can of worms we're all guilty of adding to. A good case in point was her list. It's not that there was anything wrong with it, but there's a lot of assumption behind it. Even my own preferences in the situation run contrary to my recommendations to others because my situation is different from everyone else's. And there are times where my situation will run exactly to my recommendations, as it is situational and as is any CCR diver diving in a mixed team.

Nope the OP was about both from the beginning but you may be right it may be too broad a topic for one thread.

I think that this thread is suffering from mission creep, and we are coming up with all sorts of unusual scenarios involving hypoxic dil, deco, atypical configurations, etc... I don't think that a once a year single tank vacation diver is going to be instabuddied with someone diving an expedition grade rig doing some major dive.

The point is that it is becoming more and more likely that a vacationing CCR diver who doesn't have a buddy, and who is doing a simple recreational dive, will be buddied with an OC diver. And some basic understanding of the issues involved would make a good sticky. It's not like the OP is recommending a course curriculum which the OC diver will then follow blindly, no matter what his or her buddy says or what gear they are carrying. It's just a starting point to make the pre-dive discussion more useful and understandable. As rebreather divers, we are so immersed in the gear and the language that we may forget that OC divers may have no idea why we have a second scuba unit clipped off to our harness.

Ken, I don't think that Sheila is saying that she would just go up to a motionless CCR diver concentrating on some task and throw the BOV switch. She said "if he doesn't respond". If my buddy really confirms that I am unresponsive to any and all stimuli, I would like him or her to do that and at least give me a chance. Of course, if you feel strongly about that, and you were buddied with an OC diver, you would just tell them not to touch the BOV no matter what. What you say to them before the dive clearly supersedes anything that someone learned once on SB.

EXACTLY what I am trying to do. Get a conversation going.. dispel misunderstandings and assumptions so when we share Recreational Non technical dives with each other we have a rudimentary understanding of what to do or not to do!

 

[bowlofpetunias]

@doctormike I have tried a couple times to come up with a list of the best Steps to take if we come across a random CCR diver unresponsive.
I also tried to put together a list of questions an OC diver needs to ask or be told in the event they are buddied with a CCR diver. You clearly have a better handle on the intricacies than I do. Would you mind trying to put one together for me here. I like your idea of a sticky if that would even be possible.

The most important thing I think is that we have initiated a conversation that hopefully gets Rebreather and Open Circuit divers thinking and communicating about how to share the dive sites safely.

 

[Gareth J]

What to ask if you (on OC) are buddied with a Rebreather diver (CCR)

1. How to open/close the mouth piece - actually physically do it.
(This includes BOV's - how to switch from CC to OC)
[1]
2. How to switch the BOV to OC - see above (if they have one)
3. How to flush the loop. (Not required if the diver has a BOV)
[2]
4. Where the Bailout gas is, and how YOU access it in the event of an OOG problem. Also WHAT will you be breathing, air/nitrox/trimix.
5. BUBBLES ARE BAD. Especially on descent. There is a very small amount of gas. Loosing gas due to a leak is very bad, as is the risk of water entering through the leak. Rebreather divers like to do bubble checks at the start of a dive. If you see bubbles warn them!



NOTE - MOST rebreather faults occur slowly, so normally a rebreather diver has time (unlike an OC diver). As long as your buddy acknowledges any alarms (there is normally an audible warning), then don't worry too much. Once the diver has descended he may take a few seconds to check all is well and ensure he has switch to high setpoint.
High workload periods for CCR divers are ascent and descent. Ensuring on descent the O2 isn't too high. On ascent ensuring it isn't too low, and that they don't go positively buoyant due to the unit injecting O2 automatically.

What to do if you find an unresponsive CCR diver

1. If you know how - switch them to OC if they have a BOV, and gas.
2. If they don't have a BOV, and you know how, flush the loop.
3. Lift them to the surface. THIS IS DIFFICULT TO CONTROL. They have an additional buoyancy cell - the breathing loop, gas here will expand. IF YOU CAN, dump this gas as well as their buoyancy device(s).
NOTE 1- once you go through 6m (18ft), you will probably find the diver becomes positively buoyant.
NOTE 2 - a BOV can make expanding gas issues worse, because the gas can't vent out of the mouthpiece which it will try to do under normal CC operation.
[3]
4. ON THE SURFACE - CLOSE THE BREATHING VALVE OR ENSURE IT IS ON O.C. Make them positively buoyant. Ideally remove the mouthpiece (AFTER CLOSING IT), so if they are breathing they get uncontaminated air.
5. From here on in its normal diver first aid. INCLUDING O2 - even if they fit. If they fit, take them off the O2 until they stop, then put them back on.
[4]



[1] On a BOV you can switch the CCR from closed circuit (CC) to Open Circuit (OC), which, at least in the short term solves a lot of issues. FAILING to close the valve (or switch it to OC), if the mouth piece is not in the divers mouth WILL result in flooding, making the diver negatively buoyant.
[2] If you can't switch the diver to OC, then flushing the loop puts clean fresh gas in the breathing loop. This solves CO2, High O2, and Low O2 issues. Note - if you don't dump the loop as you flush it, the diver will become very positively buoyant (i.e like filling a BC).
[3]- On ascent, shallower than 6m (18ft) , the diver may become positively buoyant. This is because the unit (if working), will attempt to maintain a high setpoint - which it can't do in shallow water and on the surface. Some units will return to low setpoint automatically, some need manual intervention. How to solve this is beyond what is reasonable for an unfamiliar buddy to achieve in an emergency.
[4] Flooding the breathing loop by failing to close the mouth piece or switch a BOV to O.C. will make the diver negatively buoyant. You are unlikely to be able to keep them on the surface if you flood the loop.

 

[bowlofpetunias]

@Gareth J THANK YOU!

 

[Gareth J]

The big difficulty in giving a sensible list is that too many points and people can't remember. Too much detail and people become confused, and sometimes it is counterproductive.

In many ways the best thing to do, if you have the opportunity, is to do a 'try dive' on a unit so that you get a bit of (very minimal) user knowledge. Ideally a unit like those you encounter. Mind you, when I did a try dive (actually a helped trial a training course), i ended up very expensive - I bought a unit.

Gareth

 

[stuartv]

I seriously don't understand how you cam to that conclusion from my post.. It is common here to have a smallish group dive together where there may or may not be vocalized buddy pairs. We dive as a group and watch everyone in the group.

You said (bold added by me):

I should have insisted that I get a brief on the unit and significance of that CCR but I let the fact that it was an instructor intimidate me. I should have challenged the situation.. I didn't.. I learned and I will never let that happen again.

I don't know any other way that I could take that, so maybe it's just a communication breakdown. To me, saying you will insist on something is the same as saying you will demand it, though possibly in a more polite way.

Anyway, different question: Was it part of any training that you've had to "group dive" instead of "buddy dive"?

My training has been to always have a buddy or be part of a 3 buddy team (unless I'm diving solo). If there are 4 divers, then we split into 2 buddy pairs. Each person knows they are responsible for looking out for exactly 1 or 2 other people and no more. It's fine to have multiple buddy teams staying "together". But, if someone, for example, goes OOA, they will have exactly 1 or 2 people to look for, whom they should always know where to find and be in close proximity to. There should never be a "shark in a school of fish" problem - "OMG! I need gas and there are so many people. Who do I go to??"

I have been on dives where there was a DM leading a whole group around. I still make a point of knowing exactly who MY buddy is and that they understand that they are my buddy and I am theirs and that we intend to stay together, etc..

In your loose group of 4, with one CCR diver, I wonder if you would have been better off if you had followed this procedure of formally designating buddies. If the CCR diver was your buddy, then it seems like this process would have readily facilitated a conversation to properly prepare you. "Hey, we're going to be buddies. What should I do if you start acting funny or pass out or something? Is there anything useful you can show me about your rig? If I go OOA, are you going to be able to help me? How should I handle that?"

 

[sunnyboy]

Again, I'm not getting some of this discussion. If you've taken a rescue course, you have already discussed and even done some rescues on unresponsive divers found on the bottom. The steps are the same no matter what configuration the unresponsive diver is wearing.

1. Do not put yourself in danger. Two victims is worse than one.
2. Do get the diver to the surface. If they are unresponsive, they need to be on the surface for proper medical attention.
3. If the breathing device (regulator, mouthpiece) is in the unresponsive diver's mouth, try to keep it in place while you safely (as safely as possible) get them to the surface.

There's lots of other stuff and details, but this is the essence of rescuing an unresponsive diver of any flavor. Whether OC recreational, OC technical (twins, stages, etc) or Rebreather, you do the same stuff - get them up if you can do it safely.

Farting about underwater trying to figure out which lever is what or whether the bottle is stage or bailout or what button to press is just wasting valuable time. Get them on the surface if you can do it safely.

 

[RainPilot]

Except at 100' with a hypoxic loop, a BOV switch can be the difference between bringing up a brain-dead corpse or a viable resuscitation. OC if they are breathing and you hold the mouthpiece in, they should be ok. On CCR, they may be breathing a mix rapidly approaching 0% oxygen and then they may as well be drowned.

 

[KenGordon]

Again, I'm not getting some of this discussion. If you've taken a rescue course, you have already discussed and even done some rescues on unresponsive divers found on the bottom. The steps are the same no matter what configuration the unresponsive diver is wearing.

1. Do not put yourself in danger. Two victims is worse than one.
2. Do get the diver to the surface. If they are unresponsive, they need to be on the surface for proper medical attention.
3. If the breathing device (regulator, mouthpiece) is in the unresponsive diver's mouth, try to keep it in place while you safely (as safely as possible) get them to the surface.

There's lots of other stuff and details, but this is the essence of rescuing an unresponsive diver of any flavor. Whether OC recreational, OC technical (twins, stages, etc) or Rebreather, you do the same stuff - get them up if you can do it safely.

Farting about underwater trying to figure out which lever is what or whether the bottle is stage or bailout or what button to press is just wasting valuable time. Get them on the surface if you can do it safely.

Fair point, but note that 2 is very hard and likely to contradict 1 unless you are very good, lucky or practiced.

 

[PfcAJ]

Fair point, but note that 2 is very hard and likely to contradict 1 unless you are very good, lucky or practiced.