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Thread: Bailout rebreather

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    RBW Member Pierre Lotz has a spectacular aura about Pierre Lotz has a spectacular aura about Pierre Lotz has a spectacular aura about Pierre Lotz has a spectacular aura about Pierre Lotz has a spectacular aura about Pierre Lotz has a spectacular aura about Pierre Lotz's Avatar
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    Bailout rebreather

    I've heard alot about guys carrying "a bailout rebreather" as a side mount sling instead of the usual OC way of bailing out. Since I don't know anybody in South Africa that dives like this, I'd like to get more info on this configuration. How is the bailout rebreather connected to the primary rebreather?

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    RBW Member Paua is an unknown quantity at this point Paua's Avatar
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    Cool Re: Bailout rebreather

    Hi, generally not plumbed into primary system. In very cold water you must switch back and forth between them to keep the scrubbers warm. That means good DSV and mouthpiece control.

    Usually carried by cave divers needing a redundant system that can keep up with the primary. OC bailout would require too many tanks!

    Cheers,

    Paua

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    RBW Member BlueLabelDiving is an unknown quantity at this point BlueLabelDiving's Avatar
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    Re: Bailout rebreather

    Correct,
    A Bail Out Rebreather aka BOB should be run independently, off independent supply cylinders. It should also have an ADV so the unit stays filled with diluent. There are two ways to dive a BOB; the most fail safe and cheapest way is to dive it semi closed and flush your loop every so often. If you have the luxury of reliable electronic monitoring, then an oxygen addition valve can be added. This supply should be closed/disconnected during your dive since there is always a risk of oxygen seeping in your loop. This will cause serious trouble at deep depth. But regardless of the oxygen injection, you'll want to dive SCR the first 5 minutes anyways since your scrubber needs to heat up and you need to take into account that your body will be producing copious amounts of CO2 in this 'stress' bail out.

    BOB's can be sidemount, butt mount or front mounted. The counterlungs can be built into the ccr, backmounted underneath your other ccr and wings or front mounted. All depends on what primary ccr you are running. If you're using identical ccr's mounted as twins (eg megameg) you could use just one exhalation counterlung per unit, making 2 frontmounted counterlungs each attached to their own loop. makes sense?

    You'll find two trains of thought; one is a basic bail out rebreather and is solely there to get you out, comfort is not the prime goal, but rather reliability, ease of use and compactness.
    Train two is to give you more peace of mind and just completely copy your primary ccr. An expensive and usually bulky setup.

    In the end, nearly every ccr can be used as a BOB, mostly a few adaptations need being done like a longer hose set and clamps/cambands.

    They are not the holy grail; because most divers don't swap between ccr's ever so often, close monitoring of the BOB is difficult and divers have found their BOB flooded or filled with a non-breathable gas by the time they needed it. Continuous CCR monitoring takes discipline and attitude and time, with a BOB all this is multiplied.

    I personally still stage a few stage tanks just in case...

    my two cents...


    Ben

  4. #4

    Re: Bailout rebreather

    Quote Originally Posted by BlueLabelDiving  View Original Post
    Correct,
    A Bail Out Rebreather aka BOB should be run independently, off independent supply cylinders. It should also have an ADV so the unit stays filled with diluent.
    ....
    They are not the holy grail; because most divers don't swap between ccr's ever so often, close monitoring of the BOB is difficult and divers have found their BOB flooded or filled with a non-breathable gas by the time they needed it. Continuous CCR monitoring takes discipline and attitude and time, with a BOB all this is multiplied.

    I personally still stage a few stage tanks just in case...

    my two cents...


    Ben

    I think most RB divers that have gotten into sugnifictly more than an hour deco, have thought about it.
    I don't know of any even semi commercial products that would realy give a solution.

    so It requires mutli-vendor DIY soulition. with that in mind, I think most of the divers don't feel comfortable having a DIY emergency system.

    so most divers look for other solutions (team carry, staging cylinders, praying...)

    putting cost aside, I would (along with the team I dive with) go for a BOB solution, if I felt I could trust it to get me out (when the S..t hits the fan) from the "deepest" point in the dive (assuming it was equivalent to carrying 2 80's or less)

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    RBW Member kopaz is on a distinguished road kopaz is on a distinguished road kopaz's Avatar
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    Re: Bailout rebreather

    Quote Originally Posted by maayanh  View Original Post
    I don't know of any even semi commercial products that would realy give a solution.
    ...
    putting cost aside, I would (along with the team I dive with) go for a BOB solution, if I felt I could trust it to get me out (when the S..t hits the fan) from the "deepest" point in the dive (assuming it was equivalent to carrying 2 80's or less)
    carry an RB80 with a steel 45 cuft strapped to it on one side and an 80+ cuft on the other in a sidemount.... then you can use your backmounted breather as the BOB...
    Last edited by kopaz; 14th November 2010 at 18:35.

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    Re: Bailout rebreather

    seriously I think a PASCR is a good choice for a BOB.

    I wonder if the new KISS GEM can be configured as a BOB....

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    Re: Bailout rebreather

    Quote Originally Posted by kopaz  View Original Post
    seriously I think a PASCR is a good choice for a BOB.

    I wonder if the new KISS GEM can be configured as a BOB....
    I have tried sidemounting a pSCR for bailout.
    There are some issues with the WOB due to the counterlung position of the pSCR.
    in order to be able to breathe correctly it has to sit exactly right.
    Changing the trim a bit ,the WOB goes bad.

    so after some trials I gave up considering that if ever the shit hits the fan and I would really need it..... i would really be stressed and task mounted and then adjusting my trim (with the scooter) and having a bad WOB is the last thing I want to do..


    This doesn't mean it wont work - or that you shouldn't do it - just that i considered the cons to be greater than the pros - and it didn't work for me

  8. #8
    RBW Member Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike has a reputation beyond repute Drmike's Avatar
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    Re: Bailout rebreather

    Quote Originally Posted by BlueLabelDiving  View Original Post
    divers have found their BOB flooded or filled with a non-breathable gas by the time they needed it.
    hmmm,

    bob is plumbed into dil so its always and instantly breathable at the kind of depths you would be bailing at. I wouldnt bail to a bob filled with low fo2 dil in the shallows the same way as i wouldnt bail to a low fo2 trimix bail tank in the shallows. In addition it takes less than 2 breaths to boost up the loop ppo2 - it takes far longer for your lungs to fully exchange their gas. (lung volume smooths out the initial drop in ppo2 to breathable level) if using a bob id still stage shallow deco tanks (why not their easy to stage) so wouldnt need to bail to bob shallow anyway - although i likely would after a quick squirt of o2 and a nose vent...

    my experiences using the bob i came to the conclusion that;

    1) dont have to worry about keeping loop 'warm or active'
    2) bob is for deep bail so dont have to worry what gas is in it -its breathable deep and shallow you will have easy staged deco gas.
    3) if i want to bail to it shallow i can boost the loop ppo2 in just a few breaths which doesnt give a risk of hipoxia
    4) you only have to worry about one thing - flooding


    i found even with a good adv its still possible to flood if not careful. (an adv cracking pressure can ensure you can actually retain a -ve in the bob even though the adv is connected)

    i found the very best way is to use an adv but also (to ensure no -ve up to cracking pressure of adv) use the bob CL to augment your bouyancy. In other words use the bob CL as well as your wing as you descend for bouyancy. This way you can actually maintain a +ve pressure in the bob for the whole dive - it cant flood. you have to make sure you can balance the trim out but i found this a very good way to ensure bob stays dry. on ascent bob opv takes car of venting and you can assist if needbe.


    as an aside, a bob with a poor wob is likley useable only after youve bailed to OC first and calmed your breathing.
    Last edited by Drmike; 15th November 2010 at 00:37.

  9. #9
    This is serious......mum Dave & Sandy has a spectacular aura about Dave & Sandy has a spectacular aura about Dave & Sandy has a spectacular aura about Dave & Sandy has a spectacular aura about Dave & Sandy has a spectacular aura about Dave & Sandy has a spectacular aura about Dave & Sandy's Avatar
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    Re: Bailout rebreather

    We've started using BOB's as OC bailout becomes questionable in terms of dives requiring long hangs.

    We have mounted an Inspo scrubber to the side of our rEvo using the locking bracket system provided by rEvo. The Inspo lungs are mounted in the usual postion on the rEvo harness (OTS).

    Electronic monitoring is via 3 cell Shearwater with O2 and dil coming from independant off board sources via the Inspo mannual adds. The Classic head has been striped of the old electronics and the holes plugged.

    We have BOV's on the Inspo plumbed to off board dil. No ADV. Whenever we inhale dil via the ADV on the rEVO we mannually add dil to the BOB on descent. On the bottom we use the BOB as a source of buoyancy. PO2 is usually at the target PO2 without the need to add O2.

    We may get around to adding our old ADV's but for the time being the sytem works.

    The aim was to device a simple BOB using parts we already had and could be quickly set up in the field (It takes us around 10min to attach the sytem entirley to our rEVO.

    Keeping the scrubber warm has been proven to be a myth by Paul R when he conducted tests. The only time we swap to our BOB is at the target depth early in the dive to check that it hasn't flooded on descent.

    Cheers
    Last edited by Dave & Sandy; 15th November 2010 at 01:30. Reason: Spelling

  10. #10
    RBW Member kopaz is on a distinguished road kopaz is on a distinguished road kopaz's Avatar
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    Re: Bailout rebreather

    I thought the GEM used a valve on the DSV to expel gas - not the lungs...

    So if that is true the WOB should not be bad.

    You can then use the GEM as a gas extender (hence the name).

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