Pony bottles VS stage bottles

[Charlie99]

A few million bazillion cubic feet of air at 1atm. Just 40' away.

 

[Amphibious]

I used an AL40 slung like a Stage.

a tank mounted pony is an entaglement hazzard and requires you remove your BC to manipulate it. a Stage-Style pony is very easy to manage.

an H-valve isn't redundancy.

 

[Rick Murchison]

an H-valve isn't redundancy.

Now where in the world did you get that? An "H" valve has fewer failure points and greater reliability than manifolded doubles and provides two completely independent gas delivery paths.
Rick

 

[Amphibious]

still a SINGLE gas source.

all it would take is a burst disk to go and you're hooped.

and before someone cries "oh that will never happen", one went one my back just as I rolled off a boat. it;s loud, it's no fun, and I couldn't hear anything for quite some time.

 

[drbill]

Can't answer this with the options given. If I am diving solo to 130 ft or so I dive a 19 cu ft pony bottle attached to my primary tank. If I am diving 130-180 ft solo I include a 30 cu ft stage bottle for double redundancy.

 

[MissyP]

If I am diving solo to 130 ft or so I dive a 19 cu ft pony bottle attached to my primary tank.

Unlike Dr B, I'd never go past recreational depths as a solo diver.. !! I'm not that brave lol (plus I don't have the training) ..
I dive with a 19 cu ft pony attached to my primary tank.

 

[Rick Murchison]

still a SINGLE gas source.

all it would take is a burst disk to go and you're hooped.

and before someone cries "oh that will never happen", one went one my back just as I rolled off a boat. it;s loud, it's no fun, and I couldn't hear anything for quite some time.

By that standard, manifolded doubles are also still a SINGLE gas source. All it would take is for an isolator o-ring to go and you're hooped. And before someone cries "oh that will never happen" I saw one go on a friend's rig just before he was going to put it on to dive it.
So if we accept that standard (there exists a single point where a failure - no matter how remote the chance - can drain all your gas) only independent tanks satisfy "redundancy." But then you can't get to all the gas if you have a single reg failure. I guess we're just hooped no matter what.
For me... an "H" valve satisfies redundancy as well or better than manifolded doubles. The only reason I use doubles is because the dive plan calls for the additional gas.
Rick

 

[JimC]

By that standard, manifolded doubles are also still a SINGLE gas source. All it would take is for an isolator o-ring to go and you're hooped. And before someone cries "oh that will never happen" I saw one go on a friend's rig just before he was going to put it on to dive it.
So if we accept that standard (there exists a single point where a failure - no matter how remote the chance - can drain all your gas) only independent tanks satisfy "redundancy." But then you can't get to all the gas if you have a single reg failure. I guess we're just hooped no matter what.
For me... an "H" valve satisfies redundancy as well or better than manifolded doubles. The only reason I use doubles is because the dive plan calls for the additional gas.
Rick

I agree Rick, I don't think manifolded doubles are appropriate for solo diving ether. There are all KINDS of failure modes with them that can leave you with less gas than you require to exit. This is why solo cave divers ether dive independents (sidemount) or carry bailout in addition to running 1/3rds on there backgas.

IMHO, If your going to solo dive you require a completely separate system with enough gas to bailout. Manifolded doubles and H-Vavles don't cut it. They are great tools when you have a buddy around but provide to many ways to have a single failure bite you.

 

[Soggy]

If, and only if, you use the stage bottle for extending bottom time it offers no redundancy. That's your choice. Not a mandatory or "correct" configuration (nor is mine for that matter).

What you are describing is not a stage bottle. A stage bottle is, by definition, used to extend your bottom time/penetration distance/etc.

Slinging a tank *like* a stage bottle does not define that bottle's usage. If you call it a pony bottle, it is used for emergency bailout. If you call it a stage (more correctly, "bottom stage"), it is used to extend your time underwater and should carry the same gas you have on your back. If you call it a decompression stage it is used to accelerate decompression and will contain a high FO2.

I was merely trying to get terminology straight so that everyone understands the topic. I don't personally solo dive, but were I to, I would choose to dive independent doubles since they provide 100% redundancy. They don't work so well in a team environment, but for solo, I think they make the most sense.

 

[Rick Murchison]

IMHO, If your going to solo dive you require a completely separate system with enough gas to bailout. Manifolded doubles and H-Vavles don't cut it. They are great tools when you have a buddy around but provide to many ways to have a single failure bite you.

I would choose to dive independent doubles since they provide 100% redundancy. They don't work so well in a team environment, but for solo, I think they make the most sense.

Nothing provides 100% redundancy (your "redundant" second bottle could quietly leak by a tank neck o-ring unnoticed while you're swimming along captivated by other things, or by way of an unnoticed freeflow if you just forgot to turn it off). There are simply "acceptable levels" of redundancy. I accept the level of manifolded doubles, "H" valves, ponies, independent doubles...
But... and this is a very big but... I only solo dive in the most benign conditions: no deco, no overhead, no low vis with entanglement hazards. Even then I much prefer at least one buddy, and for the kind of tech/overhead dives I like to do a team of three is usually optimum. I understand and appreciate the unique advantages and disadvantages of the various choices, including buddies, and on a given dive the optimum equipment may be any of the arrangements we've considered, or something else entirely. (long tight muddy sumps leap to mind )
Rick