Considering a Bail-out rebreather

JonnyB · 3rd August 2006, 06:34

Quote: (Originally Posted by divelermentov)

hi cedrik

well done article,

but at a dirfferent note, on the pic in teh article, what is your mouth piece configuration ? I can't quite make it out.

Cheers Christian

Christian,
That would be an M48 mask with the OC pod.

/Jonny

cedricverdier · 3rd August 2006, 12:35

Quote: (Originally Posted by JonnyB)

Christian,
That would be an M48 mask with the OC pod.

/Jonny

Right!

RonMicjan · 3rd August 2006, 21:33

Nice article Cedric. On the question of a small amount of OC for sanity breath, why not just go open loop until one can deploy the BOB? On the meg, it is quite difficult to get a cocktail, without knowing its coming (big change in WOB as the plenum fills up) and then some acrobatics to get the drano past the T peice and into the DSV. that should, in theory, allow enough time to get the BOB out and running.

One question i have is:
how to plumb in gasses, do we
have 2 cylinders attached to BOB, with the extra weight etc penalty, but redundant
or
have hoses from the primary systems long enough to attach to BOB

Failure modes include
loss of diluent, (mostly no problem, just end dive and no further descending, OK for ocean or sinks, but bad for caves with lots of up and down, if cave diving, bring along small cylinder of dil for BOB)

Loss of O2 (keep a 6cf cylinder on BOB for that reason)

loss of loop integrity (fine, switch to BOB using primary system's gas supply)

Loss of electronics (SW to BOB as above)

scrubber failure (open loop while switching to BOB)

So with this in mind, BOB with a small supply of O2 would be enough to get oneself out of most everything except caves with lots of up and down

I agree with the cocktail problems and the puking (i dont know what the brits refer to as tossin', and I really dont want to know. Im sure Steve will be intimatly familer with the process

) Its an ongoing thing that makes ya just want to give up and die so you can stop puking, been there, done that. It can also spasm your larnyx and prevent an open airway, so unless you want an embolism, you have to wait at depth to let it relax again. (not an easy thing)

I dont have an easy solution for the cocktail problem and BOB, other than buy a MEG.

As far as I know, there have been no cocktails on megs, but there have been a couple floods from folks not threading the breathing hoses onto the head properly, and having them pop off during ascent. this is quite apparant when it happens (duh) but a proper predive catches this problem as it is mentioned twice during the checkoff.

I have a couple neat ideas for the BOB, but would like to develop it myself at some point (like when I hit the lottery this saturday)

thinking points:

how much diluent would be used every dive to keep BOB from imploding? can the CL's be strapped down, collapsed, or some such to keep this a minimal amount while still making it idiot proof to deploy?
I would be comfortable with only 2 sensors having done 2years of CCR Dolphin diving with exactly that, how about others?
Definitly manual O2 injection, or leaky valve KISS type (to keep cost down)
How much capacity does the unit need? equal to primary, rule of thirds?
what would be a reasonable cost for such a unit?
How often would you change the scrubber, if the unit was never used? And the whole idea here is to never use it. Like an insurance policy...

webhead · 3rd August 2006, 22:02

Quote: (Originally Posted by RonMicjan)

As far as I know, there have been no cocktails on megs

You didn't know that after the dive, the Meg is a great place to put your beer?

J. V. · 3rd August 2006, 22:04

Quote:

How often would you change the scrubber, if the unit was never used?

At a time, I used a Castoro as BOB. Every two or three dive I put the BOB's sorb in the primary breather, and fresh sorb in the BOB.

cedricverdier · 4th August 2006, 01:41

Quote: (Originally Posted by RonMicjan)

Nice article Cedric. On the question of a small amount of OC for sanity breath, why not just go open loop until one can deploy the BOB? ...

Open loop: very small amount of diluent in the on-board tank. enough for CCR, maybe not enough for a OC on a deep dive. And so easy to switch to OC for those who have a BOV (kiss, etc)

Quote: (Originally Posted by RonMicjan)

One question i have is:
how to plumb in gasses, do we have 2 cylinders attached to BOB, with the extra weight etc penalty, but redundant
or
have hoses from the primary systems long enough to attach to BOB

a small O2 tank should be enough. diluent can be provided by the off-board diluent/bail-out tank

Drmike · 4th August 2006, 03:41

Ive practically finished the design for my BOB now (side mounted twin CL, 2 sensors with passive display. Dil feed off divers wing inflation/bottom bail gas, O2 from divers offboard O2 tank. (On deep cave dives often divers carry additional offboard O2 as onboard 2 or 3L can be too little)

I designed the bob for use in deep cave/deep wreck in the deeper section where OC gas consumption would be very high/tanks a pain to stage/retrieve. Its a real pain on deep dives staging the deep tanks (and retrieving them afterwards) the shallow tanks are not an issue and can be staged during warm up dives or placed by support divers. The idea is that the bob reduces the number of tanks to be staged or carried deep and makes the logistics of setting up the dive easier/cheaper.

For this reason no need for a kiss valve or electronics, diver can run manually or just run semiclosed (on the deep sections of dives its not an issue due to slow ppo2 drop off rate) I want the BOB to be as simple as possible with least number of dynamic o-ring seals/fittings or anything that can go wrong.

In use the idea being at regular intervals during the dive diver will go to bob and check semiclosed operation (not flooded) if Ok dive continues, if not OK the dive is turned. In a 2 person team that will provide considerable safety as both divers will have a bob so if a diver bails off primary Rebreather there in theory should be two working bobs available to use.

The bob will be worn side mount with dsv under divers chin. Or.... two bobs either side and no back mount Rebreather

hmm yeh that sounds like it could be real fun!

Its not going to be ready for at least a month due to other commitments - but should be interesting.

AM · 4th August 2006, 05:24

Quote: (Originally Posted by Drmike)

In use the idea being at regular intervals during the dive diver will go to bob and check semiclosed operation (not flooded) if Ok dive continues, if not OK the dive is turned. In a 2 person team that will provide considerable safety as both divers will have a bob so if a diver bails off primary Rebreather there in theory should be two working bobs available to use.

Hi Mike

So what would this mean in practice, if the BOB was deployed (in test) at the deep section and not functioning appropriately, would both divers then have to call the dive and rely on the one remaining bail out rebreather between them?

Regards

AnneMarie

Drmike · 4th August 2006, 05:57

Quote: (Originally Posted by am)

Hi Mike

So what would this mean in practice, if the BOB was deployed (in test) at the deep section and not functioning appropriately, would both divers then have to call the dive and rely on the one remaining bail out rebreather between them?

Regards

AnneMarie

If one bob was found to have failed at that point there is still one working bob (and nobody needs it yet as nobody has bailed) so it could be argued that it would be ok to continue the dive for as long as the other bob is ok. However, seeing as both bobs are the exact same design, prepped at the same time, rigged the same way & filled from the same source of sorb there is a higher risk that both could fail for same reason at similar time.

For that reason I think I would turn the dive as soon as one bob is found to have failed.

Mdemon · 4th August 2006, 08:37

Quote: (Originally Posted by RonMicjan)

how much diluent would be used every dive to keep BOB from imploding?
Definitly manual O2 injection, or leaky valve KISS type (to keep cost down)

I'm currently feeding both Rebreather's from one dil tank and haven't noticed a huge increase in gas use. Something to be aware of is that the ADV keeps my BOB on the most minimum of min loop volume. If the main dil bottle gets lost and something prevents me from taking a lungful over from the primary Rebreather (unlikely combination, I know) then I would have to head up pretty quick to get a breatheable volume. I have considered a crack bottle of rich mix as a backup to this - it'd probably give me a lungful at depth. But it's more crap to carry...

Manual injection is how I'm doing it but I haven't tried this very deep yet - I'm wary of how difficult it might be to avoid spiking. That said, at depth the manual inflators hardly seem to do anything so it might not be that bad. Maybe a KISS-type valve would be a nice parachute system too?

I like the idea of swapping unused BOB slime to the main Rebreather.

Did anyone see the Divex deep rebreather on therebreathersite? I liked the idea of the ripcord for deploying lungs on the sidemount. Maybe breakaway panels would be better though.

3rd August 2006, 06:34	#41 (permalink)
JonnyB Johnny The Hatch Current Rebreather/s: MK 15.X Titan Other CCR Other SCR Home Build Other Rebreather/s: Not Bought Yet Inspiration Classic Megalodon Sport Kiss Classic Kiss Other CCR Other SCR Home Build Join Date: Jan 2005 Location: Sweden (Stockholm)/Cyprus(Ayia Napa) Posts: 962	Re: Considering a Bail-out rebreather Quote: (Originally Posted by divelermentov) hi cedrik well done article, but at a dirfferent note, on the pic in teh article, what is your mouth piece configuration ? I can't quite make it out. Cheers Christian Christian, That would be an M48 mask with the OC pod. /Jonny __________________ A quote from Crazyduck - In remembering our own Rob Davies. "Outbound flight 777 heavy you are cleared for flight Due west into that warm red Texas sunset You have angels on your wings and divers memories on your six." Rest In Peace http://www.divetekcyprus.com http://www.diveccr.com
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3rd August 2006, 12:35	#42 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 494	Re: Considering a Bail-out rebreather Quote: (Originally Posted by JonnyB) Christian, That would be an M48 mask with the OC pod. /Jonny Right! __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
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3rd August 2006, 21:33	#43 (permalink)
RonMicjan Cap Ron scourge of the NW Current Rebreather/s: Megalodon Dolphin Home Build Other Rebreather/s: Sport Kiss Classic Kiss Dolphin Home Build Join Date: Feb 2005 Location: Cape Disapointment, The Graveyard of the Pacific Posts: 1,083	Re: Considering a Bail-out rebreather Nice article Cedric. On the question of a small amount of OC for sanity breath, why not just go open loop until one can deploy the BOB? On the meg, it is quite difficult to get a cocktail, without knowing its coming (big change in WOB as the plenum fills up) and then some acrobatics to get the drano past the T peice and into the DSV. that should, in theory, allow enough time to get the BOB out and running. One question i have is: how to plumb in gasses, do we have 2 cylinders attached to BOB, with the extra weight etc penalty, but redundant or have hoses from the primary systems long enough to attach to BOB Failure modes include loss of diluent, (mostly no problem, just end dive and no further descending, OK for ocean or sinks, but bad for caves with lots of up and down, if cave diving, bring along small cylinder of dil for BOB) Loss of O2 (keep a 6cf cylinder on BOB for that reason) loss of loop integrity (fine, switch to BOB using primary system's gas supply) Loss of electronics (SW to BOB as above) scrubber failure (open loop while switching to BOB) So with this in mind, BOB with a small supply of O2 would be enough to get oneself out of most everything except caves with lots of up and down I agree with the cocktail problems and the puking (i dont know what the brits refer to as tossin', and I really dont want to know. Im sure Steve will be intimatly familer with the process ) Its an ongoing thing that makes ya just want to give up and die so you can stop puking, been there, done that. It can also spasm your larnyx and prevent an open airway, so unless you want an embolism, you have to wait at depth to let it relax again. (not an easy thing) I dont have an easy solution for the cocktail problem and BOB, other than buy a MEG. As far as I know, there have been no cocktails on megs, but there have been a couple floods from folks not threading the breathing hoses onto the head properly, and having them pop off during ascent. this is quite apparant when it happens (duh) but a proper predive catches this problem as it is mentioned twice during the checkoff. I have a couple neat ideas for the BOB, but would like to develop it myself at some point (like when I hit the lottery this saturday) thinking points: how much diluent would be used every dive to keep BOB from imploding? can the CL's be strapped down, collapsed, or some such to keep this a minimal amount while still making it idiot proof to deploy? I would be comfortable with only 2 sensors having done 2years of CCR Dolphin diving with exactly that, how about others? Definitly manual O2 injection, or leaky valve KISS type (to keep cost down) How much capacity does the unit need? equal to primary, rule of thirds? what would be a reasonable cost for such a unit? How often would you change the scrubber, if the unit was never used? And the whole idea here is to never use it. Like an insurance policy... __________________ Ron "Life is pain princess, anyone who tells you different, is selling something", The Dread Pirate Wesley. www.tmishop.com Diving bits etc.
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3rd August 2006, 22:02	#44 (permalink)
webhead Earning the green stuff.. Current Rebreather/s: Megalodon Other Rebreather/s: Inspiration Classic Inspiration Vision Evolution Megalodon Join Date: Mar 2006 Location: East central Florida Posts: 283	Re: Considering a Bail-out rebreather Quote: (Originally Posted by RonMicjan) As far as I know, there have been no cocktails on megs You didn't know that after the dive, the Meg is a great place to put your beer? __________________ "These are not the droids you are looking for.... move along" - Obi-Wan Kenobi
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3rd August 2006, 22:04	#45 (permalink)
J. V. Custom Title Allowed! Current Rebreather/s: rEvo Other Rebreather/s: Not Bought Yet rEvo Join Date: Mar 2006 Location: Lot & Savoie Posts: 235	Re: Considering a Bail-out rebreather Quote: How often would you change the scrubber, if the unit was never used? At a time, I used a Castoro as BOB. Every two or three dive I put the BOB's sorb in the primary breather, and fresh sorb in the BOB. __________________ -------------------- Jacques NPSFQQA-EDS IT # 007 (remué non agité)
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4th August 2006, 01:41	#46 (permalink)
cedricverdier S21 M.I.B. Current Rebreather/s: Evolution Megalodon Other Rebreather/s: Not Bought Yet Inspiration Classic Inspiration Vision Sport Kiss Classic Kiss Join Date: Apr 2005 Location: Worldwide! Posts: 494	Re: Considering a Bail-out rebreather Quote: (Originally Posted by RonMicjan) Nice article Cedric. On the question of a small amount of OC for sanity breath, why not just go open loop until one can deploy the BOB? ... Open loop: very small amount of diluent in the on-board tank. enough for CCR, maybe not enough for a OC on a deep dive. And so easy to switch to OC for those who have a BOV (kiss, etc) Quote: (Originally Posted by RonMicjan) One question i have is: how to plumb in gasses, do we have 2 cylinders attached to BOB, with the extra weight etc penalty, but redundant or have hoses from the primary systems long enough to attach to BOB a small O2 tank should be enough. diluent can be provided by the off-board diluent/bail-out tank __________________ Cedric Verdier PADI Course Director, ANDI-IANTD-PSAI-TDI-DSAT-DAN-NAUI-CMAS Instructor Trainer Trimix (CCR and OC) and Cave Diving Instructor Trainer www.CedricVerdier.com DIRrebreather member
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4th August 2006, 03:41	#47 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,165	Re: Considering a Bail-out rebreather Ive practically finished the design for my BOB now (side mounted twin CL, 2 sensors with passive display. Dil feed off divers wing inflation/bottom bail gas, O2 from divers offboard O2 tank. (On deep cave dives often divers carry additional offboard O2 as onboard 2 or 3L can be too little) I designed the bob for use in deep cave/deep wreck in the deeper section where OC gas consumption would be very high/tanks a pain to stage/retrieve. Its a real pain on deep dives staging the deep tanks (and retrieving them afterwards) the shallow tanks are not an issue and can be staged during warm up dives or placed by support divers. The idea is that the bob reduces the number of tanks to be staged or carried deep and makes the logistics of setting up the dive easier/cheaper. For this reason no need for a kiss valve or electronics, diver can run manually or just run semiclosed (on the deep sections of dives its not an issue due to slow ppo2 drop off rate) I want the BOB to be as simple as possible with least number of dynamic o-ring seals/fittings or anything that can go wrong. In use the idea being at regular intervals during the dive diver will go to bob and check semiclosed operation (not flooded) if Ok dive continues, if not OK the dive is turned. In a 2 person team that will provide considerable safety as both divers will have a bob so if a diver bails off primary Rebreather there in theory should be two working bobs available to use. The bob will be worn side mount with dsv under divers chin. Or.... two bobs either side and no back mount Rebreather hmm yeh that sounds like it could be real fun! Its not going to be ready for at least a month due to other commitments - but should be interesting. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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4th August 2006, 05:24	#48 (permalink)
AM Highly amused!! Current Rebreather/s: Other CCR Other Rebreather/s: Other CCR Join Date: Feb 2005 Location: Earth. Posts: 559	Re: Considering a Bail-out rebreather Quote: (Originally Posted by Drmike) In use the idea being at regular intervals during the dive diver will go to bob and check semiclosed operation (not flooded) if Ok dive continues, if not OK the dive is turned. In a 2 person team that will provide considerable safety as both divers will have a bob so if a diver bails off primary Rebreather there in theory should be two working bobs available to use. Hi Mike So what would this mean in practice, if the BOB was deployed (in test) at the deep section and not functioning appropriately, would both divers then have to call the dive and rely on the one remaining bail out rebreather between them? Regards AnneMarie __________________ Attitude keeps you alive
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4th August 2006, 05:57	#49 (permalink)
Drmike Custom Title Allowed! Current Rebreather/s: MK 15.X Ouroboros Other CCR Home Build Other Rebreather/s: Inspiration Classic Other CCR Home Build Join Date: Feb 2005 Posts: 3,165	Re: Considering a Bail-out rebreather Quote: (Originally Posted by am) Hi Mike So what would this mean in practice, if the BOB was deployed (in test) at the deep section and not functioning appropriately, would both divers then have to call the dive and rely on the one remaining bail out rebreather between them? Regards AnneMarie If one bob was found to have failed at that point there is still one working bob (and nobody needs it yet as nobody has bailed) so it could be argued that it would be ok to continue the dive for as long as the other bob is ok. However, seeing as both bobs are the exact same design, prepped at the same time, rigged the same way & filled from the same source of sorb there is a higher risk that both could fail for same reason at similar time. For that reason I think I would turn the dive as soon as one bob is found to have failed. __________________ Cave diving is a sport Wreck diving is a sport Diving in general is a sport 'Rebreather diving' is not a sport its the delusional obsession with a highly dangerous and often inappropriate piece of equipment
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4th August 2006, 08:37	#50 (permalink)
Mdemon SiegeEngine II Current Rebreather/s: Inspiration Classic Home Build Other Rebreather/s: Inspiration Classic Home Build Join Date: Feb 2007 Location: SWUK Posts: 1,906	Re: Considering a Bail-out rebreather Quote: (Originally Posted by RonMicjan) how much diluent would be used every dive to keep BOB from imploding? Definitly manual O2 injection, or leaky valve KISS type (to keep cost down) I'm currently feeding both Rebreather's from one dil tank and haven't noticed a huge increase in gas use. Something to be aware of is that the ADV keeps my BOB on the most minimum of min loop volume. If the main dil bottle gets lost and something prevents me from taking a lungful over from the primary Rebreather (unlikely combination, I know) then I would have to head up pretty quick to get a breatheable volume. I have considered a crack bottle of rich mix as a backup to this - it'd probably give me a lungful at depth. But it's more crap to carry... Manual injection is how I'm doing it but I haven't tried this very deep yet - I'm wary of how difficult it might be to avoid spiking. That said, at depth the manual inflators hardly seem to do anything so it might not be that bad. Maybe a KISS-type valve would be a nice parachute system too? I like the idea of swapping unused BOB slime to the main Rebreather. Did anyone see the Divex deep rebreather on therebreathersite? I liked the idea of the ripcord for deploying lungs on the sidemount. Maybe breakaway panels would be better though. __________________ www.southwestmafia.com "Once the agenda-monkeys and perfect-worlders have moved on, perhaps we can do some diving?"
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