CBL on a rebreather casualty.

[sandman]

I'm buying a CCR and would like to know if there is a specific / alternate way of lifting an unconcious CCR casualty for when i practice with a buddy.

I would assume that the lift is the same & my reasoning would be as follows:

The counter lung should not be vented off by the rescuer as it will potentially leave the unconcious diver with no air supply.
Also because the counter-lung will self vent on ascent anyway.

As the expanding air in the C/L will add to buoyancy this will mean that the rescuer will just have to vent more air from the BC & suit.

But i may be wrong!! Any advise please?

[Ian W]

I'm still new to RB diving so I wont say this is the correct way but...

Currently I dive a YBOD with a 3L side mount for bail-out.
With this set-up I find that I can control my buoyancy using the counterlung's with air in DrySuit for comfort. When I have practised CBL, as a victim, I have found that a quick squirt of Dil, only using air at present, gives enough extra buoyancy to start a lift. On the ascent the CL's dump at the correct point for a nice controlled ascent.
My view of this is that if I'm unconcious underwater and I still have the mouthpiece in, then at least I will be able to breath whats in my dil, air.

This works for me at the moment, I need to see what difference 7l's side slung make.


I'm buying a CCR and would like to know if there is a specific / alternate way of lifting an unconcious CCR casualty for when i practice with a buddy.

I would assume that the lift is the same & my reasoning would be as follows:

The counter lung should not be vented off by the rescuer as it will potentially leave the unconcious diver with no air supply.
Also because the counter-lung will self vent on ascent anyway.

As the expanding air in the C/L will add to buoyancy this will mean that the rescuer will just have to vent more air from the BC & suit.

But i may be wrong!! Any advise please?

[Nigel Hewitt]

The counter lung should not be vented off by the rescuer as it will potentially leave the unconcious diver with no air supply.
Also because the counter-lung will self vent on ascent anyway.

NO!

The casualty won't be holding the mouthpiece in firmly so the increasing volume will just pop it out of their mouth before the OPV opens. Also the inject will fire and be pumping O2 in as you ascend so it is not just expansion you are venting.

You need to vent the counterlung and if they don't have an ADV to repleanish the loop it is far better to not get much of a breath than to get water. Don't forget to switch down the setpoint, but if you are lifting to the surface it can wait until then. True it wastes gas but that is hardly a significant problem if you have had to resort to a CBL.

Now if you can tell me a good place to hold them by...

[Mike Rowley]

The BSAC Inspiration CCR Course deals with both CBL and tow and AV in both theory and practical sessions. CBL is actually very similar to OC as you have deduced. However, if you consider the reasons for CBL they basically fall into two categories,

1. unconscious diver
2. conscious diver who is incapacitated for some reason.

In the first case the casualty will have no control of his/her mouthpiece and may well have let it fall from their mouth. In this case the imperitive is to get the casualty to the surface as soon as safely possible. The main concern is controling the expanding gas in the counterlungs and the suit or BC to achieve a steady but constant lift. This is achieved in exactly the same way as for OC, the only difference being that the rescuer has two volumes of expanding gas to deal with instead of the usual one, plus of course his/her own.

For this reason amongst others it is not a wise strategy to opt for gas in the drysuit for comfort plus gas in the BC for bouyancy control since in this case there are three gas volumes to control, six if there are two CCR divers who are both adopting this strategy.

It may be possible to hold the mouthpiece in the casualties mouth with the back of your hand you are using to operate the BC controls but the important thing is to get the casualty to the surface, consolidate their bouyancy on the surface and then deal with the first aid and rescue.

In the second case the casualty will most likely be able to control their own loop volume leaving you to deal with the bouyancy of the suit or BC.

The idea of controlling ones bouyancy by the counterlung as put forward by Ian should be thought about very carefully. I don't want Ian to think I am having a go at him but I would urge him to think about this.

The maintenance of minimum counterlung volume is very important with CCR diving for minimising the work of breathing, keeping dead space to a minimum, maintaining a comfortable position and very importantly facilitating rapid gas changes in emergency or reality check proceedures such as diluent flushes. The larger the gas volume in the counterlungs the more gas will need to be changed to alter the PO2 or replace potentialy poisonous gas and consequently, the longer it will take.

Maintaining minimum volume is important when operating in semi-closed mode which is an important tool for extending your gas in an emergency whilst swimming horizontally.

Hope this helps.

Mike
BSAC Technical Development Leader.

[Ian W]

The idea of controlling ones bouyancy by the counterlung as put forward by Ian should be thought about very carefully. I don't want Ian to think I am having a go at him but I would urge him to think about this.

The maintenance of minimum counterlung volume is very important with CCR diving for minimising the work of breathing, keeping dead space to a minimum, maintaining a comfortable position and very importantly facilitating rapid gas changes in emergency or reality check proceedures such as diluent flushes. The larger the gas volume in the counterlungs the more gas will need to be changed to alter the PO2 or replace potentialy poisonous gas and consequently, the longer it will take.

Thanks for your comments on this, I will think about what you have said. But to explain my point, I am not putting any additional gas into the lungs on a normal dive. I only use what the ADV adds. I find that this, along with a comfort addition to my dry suit, is all the buoyancy I need.
That is not to say that when I change configuration,larger bailout, it wont be different. At that time I may find that to control my buoyancy and keep a minium loop volume, I need to make use of the wing.

Ian

[sandman]

Thanks for all comments,
Very informative.

I have enough to progress this with DO's & instructors before attempting O/W drills.
I will certainly adopt suit & counterlung use only, reserving BC for emergencies, as this sounds like good R/B practice regardless.