Dude the majority of divers don't wear any pony whatsoever......
How low with spare air
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And then there is the question of would a diver with a larger pony be more inclined to use that pony to extend a dive rather than reserve it for emergency use only? Why do you think some ops allow a 30cf pony but not a 40 cf pony?
victorzamora
Contributor
Lynne, I totally agree with that. I agree that a well-trained, vigilant buddy is by far the safest bet. However, I can't say that that's always possible. I was buddied with a HORRIFYINGLY poor diver in Mx. Had anything have happened to my gear, it would've been at least me dying. A pony wouldn't have been unwelcome.
One thing about carrying a tiny pony, like the Spare Air, is that it may cause a false sense of security. Too many people purchase one without doing any thinking other than "the ad says it'll save my life" and then don't train anywhere beyond "I'll just breathe off of this if everything goes badly." A pony bottle of any size is a tool in the arsenal of a diver, not the answer to all safety concerns. It requires practice, discipline, and forethought....both in its deployment and in its utilization (taking it with you in the first place). SafeAir has marketed itself as an insta-fix for bad training, and as an automatic solution. It is neither of those things.
However, if you ARE carrying a pony bottle for redundancy it is unrealistic to think that in the case of something actually going wrong that 3 cubic feet is enough for any reasonable depth. In the vast majority of scenarios, this happening would be relatively unexpected. Immediate and flawless deployment of the pony would be FAR from the norm. Breathing rates would be elevated drastically. Even if everything happened quickly and smoothly, there's no way to start an ascent at the same instant your gear fails while transitioning to a pony. The paradigm set forth under DumpsterDiver's post regarding the need for a minute at depth before responding, and then SAC rates noticeably higher than 1ft3/min is inaccurate. My numbers depicting a 25 second ascent time from 100ft was using a SAC rate of 1.2 and no excessive wait time at the bottom. The figure I calculated for the "standard" ascent rate was 60ft/min below 30ft and 30ft/min above 30ft. At 100ft, a SAC rate of 1ft3/min would mean less than 45 seconds total at depth. This doesn't take into account purging the regulator or a short fill/leak or any reserve (using every single molecule). This ignores all effects that aren't a perfect-world scenario.
One thing about carrying a tiny pony, like the Spare Air, is that it may cause a false sense of security. Too many people purchase one without doing any thinking other than "the ad says it'll save my life" and then don't train anywhere beyond "I'll just breathe off of this if everything goes badly." A pony bottle of any size is a tool in the arsenal of a diver, not the answer to all safety concerns. It requires practice, discipline, and forethought....both in its deployment and in its utilization (taking it with you in the first place). SafeAir has marketed itself as an insta-fix for bad training, and as an automatic solution. It is neither of those things.
However, if you ARE carrying a pony bottle for redundancy it is unrealistic to think that in the case of something actually going wrong that 3 cubic feet is enough for any reasonable depth. In the vast majority of scenarios, this happening would be relatively unexpected. Immediate and flawless deployment of the pony would be FAR from the norm. Breathing rates would be elevated drastically. Even if everything happened quickly and smoothly, there's no way to start an ascent at the same instant your gear fails while transitioning to a pony. The paradigm set forth under DumpsterDiver's post regarding the need for a minute at depth before responding, and then SAC rates noticeably higher than 1ft3/min is inaccurate. My numbers depicting a 25 second ascent time from 100ft was using a SAC rate of 1.2 and no excessive wait time at the bottom. The figure I calculated for the "standard" ascent rate was 60ft/min below 30ft and 30ft/min above 30ft. At 100ft, a SAC rate of 1ft3/min would mean less than 45 seconds total at depth. This doesn't take into account purging the regulator or a short fill/leak or any reserve (using every single molecule). This ignores all effects that aren't a perfect-world scenario.
dumpsterDiver
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Your bolded comment is ridiculous! It gets hard to breath, you spit the reg, stuff the one that is hanging under your neck into your mouth, give 3 kicks toward the surface, relax and ride the expanding air in the BC , and then grab the console to see your air pressure and computer for ascent information. Is that hard or complicated?
What exactly do you need to accomplish on the bottom (say when you can't breath anymore)?
victorzamora
Contributor
Are you saying you sprint to the surface the second you feel the slightest change in work of breathing? You don't look for problems/solutions first?
DevonDiver
N/A
Realistically, and following safe diving practices and training you are given:
1) Comprehend that you actually have a problem.
2) Analyse what is wrong.
3) Conclude what the problem is.
4) Calculate what resources you have available.
5) Consider options to solve the problem.
6) Decide upon the optimum solution.
7) Communicate your problem and intention to your buddy.
8) Co-ordinate and confirm your buddy understands
9) Enact your solution.
What you seem to be suggesting is:
1) Bolt to the surface.
...which is odd; from a former dive instructor...
1) Comprehend that you actually have a problem.
WTF?...
2) Analyse what is wrong.
Hmmm... I can't breathe properly, look at gauge- ah!
3) Conclude what the problem is.
Yep- I'm OOA
4) Calculate what resources you have available.
Have a pony here, a buddy over there and unlimited air up
5) Consider options to solve the problem.
Switch to pony, swim to buddy or swim up.
6) Decide upon the optimum solution.
Pony it is.
7) Communicate your problem and intention to your buddy.
Get attention and signal
8) Co-ordinate and confirm your buddy understands
OK
9) Enact your solution.
Swim up
Depending on experience, comfort and control, the first 6 steps take... maybe 5 seconds. I believe DumpsterDiver is speaking of his experience whilst diving solo negating the need for the last few steps..... except for number 9.
Inexperienced people in the water are much more likely to panic when confronted with the burning reality that they cannot breathe 'right now dammit!' Many divers are breathing so fast that they cannot CESA for even 10m.
Just for the benefit of all those users of Imperial units out there (so quick to cast off the Empire, so slow to adopt those revolutionary metric units that make life so easy...), the OP is actually talking about diving with a 20cf pony containing 'spare' air, NOT the fabulously pointless product branded as SpareAir...
The answer remains, however, as lots of people have said, that you don't include 'spare' or 'redundant' or whatever-you-want-to-call-it air in your gas planning. It's spare, or redundant, after all. If nothing goes wrong, you should only ever be breathing from your pony when you're practising deploying and breathing from your pony (which you should do on a regular basis - switching gas supplies is emphatically not something you'll just work out when you need it. I've seen someone ignore an Al80 slung at his side and rocket to the surface from a frightening depth because his primary tank wasn't fully open and his reg was breathing hard).
GrumpyOldGuy
Contributor
I guess if you want to analyze, conclude, calculate, consider, decide, communicate and coordinate, then you should sling a 40 pony to allow you enough time to do all that.
My purpose of using a pony is to be 100% self reliant if I am solo or my buddy is not next to me. I drill the snot out of myself in practice. I am perfectly comfortable with a reg swap and immediate ascent to 20' and then ponder if I want to do a prolonged s/s before surfacing. Since I dive recreational profiles, I really don't see a downside.
Hatul
Contributor
I just want to add two points. First most of us are aware that the amount of weight you carry is directly proportional to the displaced volume of the cylinder and any other gear that goes along. It's Archimedes principle, to be neutrally buoyant it has to weigh the same as the displaced volume of water. And it makes no difference what the cylinder is made of. If it's light you just need to take more lead to compensate. So if you're a shore diver like me the bigger the tank the more weight you have to shlep around on land.
Second, where we shore dive in Southern Cal most of the sites are shallow 15-40 feet and I see some carrying Spare Air and in this context it does make sense, as you just need a few breaths to come up and there's no need to make a safety stop. It's safer than doing a CESA.
Second, where we shore dive in Southern Cal most of the sites are shallow 15-40 feet and I see some carrying Spare Air and in this context it does make sense, as you just need a few breaths to come up and there's no need to make a safety stop. It's safer than doing a CESA.
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