Is "bailout stashing" a thing?

[SouthernSharktoothDiver]

Hey all!

Full disclosure. As you can likely guess from my profile, I'm not a rebreather diver. It will be more than a decade and several more levels of certification before I become a rebreather diver, if I ever do. So this is not me asking for advice, so much as trying to scratch a curious itch. I've done enough looking into rebreathers to know that you need to carry sufficient bailout gas to finish a dive, and that the major limiter/impediment to rebreather diving is that, on a, say, 100m dive, you end up carrying a lot of spare tanks of trimix which you will (hopefully) never use. I've seen various posts about sidemounting, backmount, buttmounting, bailout rebreathers and other configurations. Thus, my question:

Is there such a thing as just carrying say, a twinset of travel gas on your back, and clipping off your necessary deco/ascent gasses to the line you're using for ascent? On the one hand, the idea of leaving necessary bailout gasses somewhere I can't see them seems terrifying and stupid, but, on the other hand, so does cave diving, yet apparently, when well trained and properly executed, it can be done safely. Thus, I wonder if leaving part of your bailout at a secure location is an acceptable practice? By the fact I haven't heard about it, I'd assume not, but still I wonder.

Once again, don't worry. I'm not a rebreather diver, I will receive proper training if I ever become a rebreather diver, and I'm not about to hop in the water and try some crazy stash-bottle stunt no matter what is said here. I just find rebreathers fascinating, and wondered if this was a thing.

 

[Underwater Tourist]

...On the one hand, the idea of leaving necessary bailout gasses somewhere I can't see them seems terrifying and stupid, but, on the other hand, so does cave diving...

In cave diving it gets even worse. Those sickos leave their primary (!) gas somewhere they can't see all the time

Its called staging and its the first thing you learn after you complete basic cave cert. For example, you would go with 3 tanks (2 primary, 1 stage), breathe down the stage to whatever pressure you are comfortable with, take it off, tie it to the line, and continue the dive leaving the stage behind you until you turn around and pickup your "stash" on the way back

 

[happy-diver]

See this chicky babe I have dived like this and with oxygen only as there are millions of dives not to 100metres

and also without any bailout because not every dive is to 100 metres but bailout is good when some times you

just want to get off the unit

 

[Submersion]

Lots of different strategies and ways of thinking around bailout. The most concise summary is that you should have enough bailout on you to (safely) get to the surface or to the next bottle.

Some people will drop their deco bailout bottles. Other's wont. Others "have to" carry less than needed for various reasons. Usually in those cases you're using team bailout or staged bailout just due to sheer amount of tanks required for the dive. Other times it might be dropping some to fit through a restriction.

In general the one "constant" is that almost no one will put themselves in a position without having something breathable to bailout to (e.g. dropping your bottom gas while on the bottom).

 

[rjack321]

Hey all!

Full disclosure. As you can likely guess from my profile, I'm not a rebreather diver. It will be more than a decade and several more levels of certification before I become a rebreather diver, if I ever do. So this is not me asking for advice, so much as trying to scratch a curious itch. I've done enough looking into rebreathers to know that you need to carry sufficient bailout gas to finish a dive, and that the major limiter/impediment to rebreather diving is that, on a, say, 100m dive, you end up carrying a lot of spare tanks of trimix which you will (hopefully) never use. I've seen various posts about sidemounting, backmount, buttmounting, bailout rebreathers and other configurations. Thus, my question:

Is there such a thing as just carrying say, a twinset of travel gas on your back, and clipping off your necessary deco/ascent gasses to the line you're using for ascent? On the one hand, the idea of leaving necessary bailout gasses somewhere I can't see them seems terrifying and stupid, but, on the other hand, so does cave diving, yet apparently, when well trained and properly executed, it can be done safely. Thus, I wonder if leaving part of your bailout at a secure location is an acceptable practice? By the fact I haven't heard about it, I'd assume not, but still I wonder.

Once again, don't worry. I'm not a rebreather diver, I will receive proper training if I ever become a rebreather diver, and I'm not about to hop in the water and try some crazy stash-bottle stunt no matter what is said here. I just find rebreathers fascinating, and wondered if this was a thing.

Most of the BO gases stashed in a cave can't be breathed at the depth you're at anyway. Carrying O2 down to 100ft is actually more dangerous than clipping it to the exit line. If you can't breath it down there carrying it is pointless and dangerous. If you cant come up that line you are dead anyway.

In OW its customary to carry all your BO with you all the time. Cause you might not make bask to the upline/anchor but if you have the gas you can deco out above you.

 

[AJ]

The question is: do you follow the same route back as you went in/down? If 100% yes, you can stash bailout at a usable depth. If not, you have to take all of it with you.

For cave diving you plan your route and, in almost all cases, go back the same route. Wreck diving is completely different. If you get blown of the wreck you want to have all your bailout with you.

 

[Tassi Devil Diver]

For open ocean dives (deep reef and or wreck) where my team plans to descend and ascend a shot line we will place shallower bailout tanks such as 70-100% oxygen on the shot.

 

[Alex Ouroboros]

Read “The Last Dive” ( a fab book btw) and that has a harrowing tale of stashing ascent bottles in the ocean environment,,,
But in caves it can be necessary so it all depends on the given situation.

Interesting question, and nothing wrong with that.

 

[SouthernSharktoothDiver]

Alright cool! So what I’m basically getting here is that for caves, this is a fairly standard practice. For open water it’s not so common, but sometimes an option if you’re dead certain you can come back the way you cane in. This makes sense.

Another question, while I have you all here, is how feasible are bailout rebreathers? In what little research I’d done into them, I’d heard that you had to worry about the bailout rebreather flooding when not in use, but I don’t have the context to know how likely/problematic that would be.

 

[Alex Ouroboros]

Alright cool! So what I’m basically getting here is that for caves, this is a fairly standard practice. For open water it’s not so common, but sometimes an option if you’re dead certain you can come back the way you cane in. This makes sense.

Another question, while I have you all here, is how feasible are bailout rebreathers? In what little research I’d done into them, I’d heard that you had to worry about the bailout rebreather flooding when not in use, but I don’t have the context to know how likely/problematic that would be.

I know a few guys using them and I’m looking in to acquiring one myself, yeah flooding is the main issue (worry) but then you really should vent the expanding gasses in that loop as you ascend, as much as there will be an OPV that’s still a difference of a few kg potentially if your lazy and don’t do it,
I’m of the mind I’d only take one if I had more than say 1hr of deco,, as why load up the lime and gases etc when an ali80 or a couple of Ali 40,s would do without the extra hassle, their place imo is really with the 80m+ stuff,, and on that note I’ll explain my personal take on it,

If I’m say doing a 100m dive with a fair chunk of bottom time my worry isn’t necessarily with the amount of gas I can carry (3 Ali 80,s I can cope reasonably well with, 4 I’m maxed out) but if I were really put in to a situation with 4hrs of deco my worry would be decompressing safely after breathing for 4hrs in the cold Atlantic in uk waters. I think the cold would be really taking it’s toll,
My next point is that to carry adequate bailout to the 120-170m depths out there (which some do as there are cracking wrecks) you cannot honestly carry enough personal gas in the event it goes wrong at the bottom,,, where as a cylinder of deep bail and a bailout unit offers an acceptable safety margin ,,, I must stress the depths and dive times I’m talking about are all up to the individuals level of risk acceptance,,, as you quickly realise your “definitely not in Kansas any more Toto”