Janos(Offline)

Although not DIR myself (mainly because of my view of the risks surround CCRs) I still believe there's a lot to be learnt from the DIR way of doing things, and I'm curious about mixed OC/CC teams.

So, my questions are:
1) Do mixed OC / CC teams happen? Or are teams exclusively OC or exclusively CC?

2) Assuming yes, how does the CC diver donate gas to the OC diver?

3) What are the protocols for bailing off the RB? Not so much the physical act of bailing off, but how / when do you inform the rest of the team?

4) Just for my own curiousity, but am I right in thinking the RB80 dumps 1/8 of it's gas every breath, as opposed to all of it's gas once every eight breaths.

Thanks,
Janos

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decoweenie(Offline)

Yes, except it is 1/10th.

Michael-Fisch(Offline)

which somehow translates to an 8:1 gas saving over the course of a dive, just don't ask me to explain why

Michael

decoweenie(Offline)

I guess if you look at the total gas usage including wing inflation and discharge upon ascend, then the "ratio" is lower.

But, technically, it still dump a fixed ratio which is 1/10. Isn't it ?

David Martin(Offline)

Janos,

See the pictures in this link, which discussed OOG drils between 2x RB80 divers. If the OOG diver was on OC the drill would be virtually the same, but slightly simpler, since the recipient wouldn't have the RB loop.
RB80 OOG

The original post is partway down this thread.
RB80 question

HTH - obviously if you need more details you'll probably need to ask someone who's more familiar with the RB80 than me!

David

davy(Offline)

according to the halcyon website it's 8:1 ratio.
Halcyon: RB80 Rebreather Introduction
see down the page.

most of the clones use 10:1 ratio...

Michael-Fisch(Offline)

The 2 chambers of the counterlung are sized to give a total 10:1 ratio that means the volume of the outer counterlung is 9x larger than the inner couterlung which is exausted on each breath. Or has the ratio been recently changed?
Buchaly had been experimenting with a 14:1 ratio counterlung for a while, which I believe he is still using on longer deeper dives, the disadvantages on shallow dives are apparant.

Michael

Joe Hesketh(Offline)

No, it's as decoweenie said: 10:1 fixed but 8:1 real world.

See Halcyon: RB80 Developer's Note (6th para from the bottom)

Anders Knudsen(Offline)

Hey,
I do not Dive RB80 so please correct me if I am wrong

Quote:

1) Do mixed OC / CC teams happen? Or are teams exclusively OC or exclusively CC?

Well in DIR I guess there is not the combination of OC and CC, but it is “normal” to mix OC and SCR :-)

Quote:

2) Assuming yes, how does the CC diver donate gas to the OC diver?

Just as with a OC diver, using the longhose, the longhose is clipped to the right shoulder D-ring with a bolt snap.
The bolt snap is attached to the longhose with a break-away ( could be just tied to an o-ring )
Then if a OOG occurs, he just donate the longhose, without having to unclip the longhose.

Quote:

3) What are the protocols for bailing off the RB? Not so much the physical act of bailing off, but how / when do you inform the rest of the team?

When you bail out, you just go to your backup regulator which is configured just like in OC, you always carry enough bailout gas to end the dive OC.
When do you inform the team?? At the same time you would have in OC diving

Quote:

4) Just for my own curiousity, but am I right in thinking the RB80 dumps 1/8 of it's gas every breath, as opposed to all of it's gas once every eight breaths.

I think this subject is already covered by others :-)

best

Anders Knudsen

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lizardland(Offline)

I think what Janos may be alluding to is that it isn't quite that simple. If the rebreather diver is still on the loop then he cannot donate the long hose in the normal way as the loop hoses will prevent the hose from uncoiling over his head. If he is going to deploy the hose properly then he will have to come off the loop at some point.

As for the question of dump ratios, I still have my scalpel for sale (advertised elsewhere) for £5, perfect for splitting hairs

[EDIT]I've had a look through the pics in the link and it appears the donor has to spit the DSV. I would have thought the donor's RB would freeflow: the open DSV becomes the highest point so the loop dumps, the bellows collapse and the injectors open but the gas just escapes through the DSV.

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