It's a good thing we have spare air, without it there would be one less dead horse to beat mercilessly.
Really, you should do a search, although I see that you've decided to go for a pony already, so it doesn't matter. It's clear that carrying a spare air increases your risk. First, it has already allowed you to dive in a dangerous situation, which I assume you other wise would not have. Second, it can give you a very false sense of security and create a secondary emergency. Third, it is allowing you to avoid solving the basic problem which is, why are you concerned about going OOA? That's the real issue, and it should be solved through dive training and behavior, not equipment.
What?! sorry, but that is bad sounds like bad advice. If this were true, then with proper training and behavior I wouldn't need any backup air at all. I will never have enough faith in my equipment to do that.
Hi mcavana: This is a long answer and more appropriate for the "Solo" section of this board, but here goes: Re-read what mattboy posted carefully. He's right.
What can happen in all areas of diving is that additional equipment is often used to solve what is really a skills problem, or to solve a perceived risk. Using equipment in this fashion actually
increases the risk because the diver feels more confident than is warranted, gets in over his/her head, then discovers the added "safety equipment" / "redundancy" will not get them out of the situation.
Your question about removing your backup regulator and using a 3.0 cu foot Spare Air as a bailout bottle on a 100 foot dive is a case in point. To your credit you correctly identified a potential risk (diving to 100 feet without a redundant air source such as a buddy) and tried to compensate for it, but incorrectly proposed an inappropriate gear solution that would actually
increase your risk.
Your risk is increased in this case because you would feel "safe" using the Spare Air and go ahead with the 100 foot solo dive ... but in reality 3.0 cu ft is inadequate to get you to the surface at a stressed breathing rate, you'd more than likely run out 1/2 way up, then you'd bolt the rest of the way, and
that could kill you.
If you know, in advance, what the limitations of 3.0 cu feet of air impose on you, then you can make a good decision on what depth it would be useful from.
The answer, at least for me: The 3.0 cu ft is not sufficient for
any depth. It is an expensive paperweight. From a depth shallow enough to be useful from, redundancy is generally not required. It does not provide enough air to get you out of an entanglement, or to otherwise problem solve underwater.
Well-maintained scuba equipment is remarkably reliable. Failures do occur, but are rare. The vast majority of OOA's are not equipment related: they are due to
operator error. Failure to plan gas consumption, failure to monitor gas consumption, or a failure to
understand gas consumption in the first place. Thus the vast majority of OOA's are a "skill's issue" and not an equipment failure.
You do need to evaluate your own skill level, the environment, and dive plan. I solo dive with exactly the same gear configuration as I buddy dive with. I do not carry a pony. But I dive in a very benign environment (warm, good viz, very low entanglement risk). I stay shallow enough (20-50 feet) that the atmosphere is my "Spare Air"
If I were diving cold water & lower viz I'd be using a very different config, possibly doubles. I do have a 30 cu foot "pony" I can sling for the occasional deeper dive... but this is for buddy dives, not solo. If I carry it on solo dives I'm using it as a small "stage bottle" to extend dive time a bit so I can explore a little further. It becomes part of my gas planning and not a bailout bottle.
My personal "comfort level": If the dive I want to do is deep enough to really require redundancy, then I want that redundancy to be in the form of a good buddy, not just a piece of equipment. I will not do a solo dive that I could not swim myself up from on a single breath.
Best wishes.
