spare air? i use one and i get laughed at
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Scuba Cobra
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John Bantin
Contributor
During a review for Diver Magazine (UK) I tried to use one for a safe ascent from 100-feet deep. (I took the precaution of having a tank on my back with plenty of air.) They never sold well in the UK after that.
A.S.H.
Contributor
What depth did you reach? Size of Spare Air used? Conditions of the dive?
John Bantin
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I might just be able to make a direct ascent to the surface from 100 feet at 30 ft/min with 3 cf. If I was OOA and depending on a Spare Air, I could probably move a bit quicker. It would certainly be better than nothing. My 19 cf pony is a better choice.
A.S.H.
Contributor
I use a 30 cf for all my dives regardless of depth, I agree, the spare air is not a great choice, considering you can get a 13, 19, 30 and a low cost reg set ( used / new ), for the same price or lower if you search a little and be much more versatile and safe.
Still doing it that fast will have a cost I'm guessing. Don't know if I could do that.
I think I'll try that next month if I have the time, just for my own curiousity and OOA training.
A.S.H.
Contributor
Thx John, I agree
I can make a direct ascent from 130' to the surface on 0 cu.ft. Tested it. 130' is nothing more than a 65' freedive.
Swimming towards the surface is far easier psychologically than swimming down and then up, or swimming horizontally. Unless conditioned by freediving practice, your brain will stop from descending long before there's any danger - but it won't stop you from ascending towards the light.
So no need to be a freediver. Any non-smoker with basic swimming ability can manage a CESA from 130+ ft when their survival response kicks in. That said, even one full breath to count on would turn the ascent from "doable" into "impossible to fail".
The real issue with Spare Air in diving is that it addresses one problem only: unexpected and complete OOA in a no-overhead environment.
You cannot disentangle yourself on a spare air.
You cannot help a diver in distress ascend on a spare air.
You cannot follow a line to escape an overhead on a spare air, too slow.
You cannot hope to fumble around find the exit without a line on a spare air.
You cannot complete even unintended emergency deco on a spare air.
You can do one thing and one thing only on a spare air: head straight for the surface ASAP.
Which in a non-overhead scenario you should already be able to do.
The other issue is that all common failures leave you with about as much air time as a Spare Air anyway.
You can still breathe off a freeflowing regulator.
You still get a couple breaths from one of the regulators after a LP hose is torn - worst-case scenario that actually happens.
You even get air after using up your tank - let's pretend your SPG was at fault and not your brain - with the last tight half-breath, and then a few bonus breaths as you're ascending and get access to low pressure air. There's actually just as much air liberated from an AL80 on ascent between 130 and 0 ft as there is in a spare air bottle.
So what is that one failure scenario, bad enough that you need a spare air, but easy enough that it will suffice, and how narrow is that goldilocks zone?
P.S. This addresses the original 1.7 cu.ft version. The 3 cu.ft. is less ridiculous.
There's also a new version, a 6 cu.ft. While holding a tank that large with your teeth is very inconvenient, and it's certainly inadequate for solo diving, if you have to fly without checked luggage, that might be a valid compromise for group rec diving.
Having witnessed some excruciatingly stupid incidents, the only place I dive without a redundant air supply at all now is the pool.
Swimming towards the surface is far easier psychologically than swimming down and then up, or swimming horizontally. Unless conditioned by freediving practice, your brain will stop from descending long before there's any danger - but it won't stop you from ascending towards the light.
So no need to be a freediver. Any non-smoker with basic swimming ability can manage a CESA from 130+ ft when their survival response kicks in. That said, even one full breath to count on would turn the ascent from "doable" into "impossible to fail".
The real issue with Spare Air in diving is that it addresses one problem only: unexpected and complete OOA in a no-overhead environment.
You cannot disentangle yourself on a spare air.
You cannot help a diver in distress ascend on a spare air.
You cannot follow a line to escape an overhead on a spare air, too slow.
You cannot hope to fumble around find the exit without a line on a spare air.
You cannot complete even unintended emergency deco on a spare air.
You can do one thing and one thing only on a spare air: head straight for the surface ASAP.
Which in a non-overhead scenario you should already be able to do.
The other issue is that all common failures leave you with about as much air time as a Spare Air anyway.
You can still breathe off a freeflowing regulator.
You still get a couple breaths from one of the regulators after a LP hose is torn - worst-case scenario that actually happens.
You even get air after using up your tank - let's pretend your SPG was at fault and not your brain - with the last tight half-breath, and then a few bonus breaths as you're ascending and get access to low pressure air. There's actually just as much air liberated from an AL80 on ascent between 130 and 0 ft as there is in a spare air bottle.
So what is that one failure scenario, bad enough that you need a spare air, but easy enough that it will suffice, and how narrow is that goldilocks zone?
P.S. This addresses the original 1.7 cu.ft version. The 3 cu.ft. is less ridiculous.
There's also a new version, a 6 cu.ft. While holding a tank that large with your teeth is very inconvenient, and it's certainly inadequate for solo diving, if you have to fly without checked luggage, that might be a valid compromise for group rec diving.
Having witnessed some excruciatingly stupid incidents, the only place I dive without a redundant air supply at all now is the pool.
Namreg 58
Contributor
I think an experienced rational diver would use the Spare Air to calmly get to one of his or her buddies who should be around the same depth and less than 45 feet away and commandeer their occy. This "race to the surface" mentality is just plain silly when there is a larger reliable air supply nearby.
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