OC bailout - why not CCR bailout?

[Mdemon]

The phrase "Twinspo" is at the back of my mind - perhaps this is in common use.

My question is really, why have a ton of additional OC bailout cylinders? Why not have an additional cut-down rebreather? Either completely independant or a second scrubber/handsets using the same counterlungs/loop?

Just curious...

[turbanator]

I then Reinhard Buchally (sp) has an arrangement like this, or did when he was diving, I think he's given up on big pushes.

IIRC he had 3 RBs.

[Dominic]

What, like the Kiss BOB? (Bail out 'breather)

[Padowan]

This has certainly been done...

One here all inboard of an oversized case: http://www.therebreathersite.nl/twinspiration.htm

And this one with an external sidemounted scrubber: http://www.therebreathersite.nl/twinspiration2.htm

And one being played with by Dave Thomson: http://www.therebreathersite.nl/twinspiration3.htm

[Padowan]

Originally Posted by Mdemon

.... using the same counterlungs/loop?
..

This would defeat the objective of a redundant unit - having a completely seperate loop if the key to a redundant system, if you use anything the same, (even using the same tanks and regs) you are back to a possible single point of failure.

Looking at the units made already, the seperate loop to still allow a CCR exit after something like a loop flood, or exhausted scrubber seems to be the key component of these designs.

[Duncan Price]

Originally Posted by Mdemon

My question is really, why have a ton of additional OC bailout cylinders? Why not have an additional cut-down rebreather? Either completely independant or a second scrubber/handsets using the same counterlungs/loop?

Second completely independent unit is the preferred choice. I couple of divers I know do this with a primary backmounted rig and a sidemounted or chestmounted bailout see (for example): http://ww1.hns.net/rebreather/images/dualrb.jpg

Beuchaly/Waldbreener use twin RB80's as do several Swiss divers (using RB80alikes). Olivier Isler was using triple RB's in the early 90's. These are all semiclosed units.

[Pierre Farrugia]

Hello Mdemon,

You saw why not a double RB, do you know that to buy one, I had to cry every single day for the past 2 years

[nigelH]

Originally Posted by Mdemon

My question is really, why have a ton of additional OC bailout cylinders? Why not have an additional cut-down rebreather?

NO! No! Not another d*m rebreather to clean and pressure check, to calibrate, to fill on the descent, to vent on the ascent and more batteries.
Two 7L stages that just need a quick gasp once a dive suit me just fine. Faults are very infrequent so keep the bail out kit simple.

nigelH

[Mdemon]

Originally Posted by Pierre Farrugia

Hello Mdemon,

You saw why not a double RB, do you know that to buy one, I had to cry every single day for the past 2 years

LOL! OK, the question was theoretical I admit!

Nigel, good point! Although Dom's BOB link is excellent, I was thinking of something more sophisticated and that's were your point becomes very valid. Looking forward to going through all the links when I get home...

Cheers, all.

John

[Dominic]

Heh. Here's an even simpler one - keep the inside of your wing disinfected & store some scrubber material inside it. Hey presto, instant & very simple rebreather