This topic just keeps coming back up, and back up again. Hell, I'm just gonna post my same reply again....
SpareAir is a complete waste of money, and a complete piece of crap. Your tanks, regs, weight systems, exposure suits, and other gear form a life-support system. Hopefully, most people view this with the seriousness it deserves, and purchase and learn to use quality life-support equipment. Anyone who purchases a SpareAir -- for any reason -- is ipso facto not thinking well about his life-support equipment. It is a gimmick.
You will never convince me that three breaths of air at 100' are in any way relevant to any life-saving situation. Anyone who runs out of air at 100' and needs a SpareAir to surface is a disaster waiting to happen, and shouldn't be diving. People that do such things kill themselves, and sometimes their buddies.
Here are some myths:
1) If I get entangled, my SpareAir will save me. Wrong -- if you get entangled enough to run your primary gas supply dry, 3 breaths will make virtually no difference. If you're in an environment where entanglement is an issue, you should be diving with rational gas management techniques (such as the rule of thirds, or, in some specialized cases, the rule of sixths). In such a situation, your buddy could go back to surface, get more gas, get more tools to free you, and be back at your side before you run dry. Further, if you're in an environment where entanglement is an issue, a good quality knife will be much more useful than a $300 SpareAir contraption. Further, if you're going to be in an environment where entanglement is an issue, the SpareAir itself presents an enormous entanglement opportunity.
2) The SpareAir will get me to the surface with a CESA. Wrong -- if you're too incompetent to manage such a basic skill as gas management, then you ipso facto will be horribly unskilled to actually use such a stupid contraption as a SpareAir. If you're stupid enough to run your tanks dry, you probably will not have the wherewithal to properly use a SpareAir anyway. Spend the $300 on pool sessions and practice how to actually manage emergencies.
3) The SpareAir will save me when my reg goes kaput and fails. Wrong -- there are paltry few situations where a reg can fail closed. Those situations, like ice diving, require real training and real equipment. The SpareAir has no place in such diving. If your HP SPG hose fails, you have a slow leak. If your tank O-ring bursts, or your first-stage HP seat fails, you will have a moderate leak. You will certainly have MUCH MORE than 3 breaths left in your primary, unless you were already run dry. Once again, anyone who lets himself go dry to begin with is waiting to kill himself. Anyone who worries about a HP seat failing after having already run dry really needs to think some more. The only conceivable way the gas supply could be completely interrupted would be to have a yoke reg literally popped completely off of the valve. This would require Herculean effort and inordinate stupidity to accomplish. It isn't a reasonable failure mode.
4) People often run out of air, so the SpareAir should be a good thing. Wrong -- the condition is correct -- people run out of air all the time -- but the conclusion is wrong -- the SpareAir is not a good idea. There is no emergency short of three simultaneous equipment failures at maximum depth or penetration that cannot be solved without loss of life by a properly formulated dive plan. In no way, absolutely no way, is the SpareAir an acceptable replacement for appropriate training, equipment, or dive planning.
I'm the first to admit that skill, technique, and knowledge are the most important qualities of a good diver, but equipment is a VERY CLOSE SECOND. I can halfway acknowledge the use of a real (50cf+) pony bottle. In moderate to extreme diving scenarios that could benefit from a pony, I'd just rather bring an AL80 stage with me for backup. The regulator is not expensive. If the reg on a proper stage bottle is too expensive for you, you are not able to make a dive that might need one. Go play checkers instead until you get a paycheck.
If I dive with someone who insists on using a pony, I do not expect him to ever crack that puppy open. If, no matter what the situation, he finds that he needs to crack open his pony, I chalk that up as a massive, unacceptable failure. At this point, that diver needs to begin seriously thinking about what led to the failure, and how he can prevent it from ever occuring again. Anyone who opens a pony more than once in his lifetime is not responsible enough to dive. Anyone who fails to adhere to a properly arranged dive plan more than once in his lifetime is not responsible enough to dive. Contrary to popular conception, a properly formulated dive plan contains contingencies for entanglements, equipment failures, and all other conceivable modes of failure. A properly formulated dive plan is conclusive, in every way, for every possibility. Anyone who finds their way out of such a plan is not responsible enough to dive.
THE SPAREAIR IS ABSOLUTELY NOTHING MORE THAN A PATCH TO MEND HOLES IN A POOR DIVE PLAN OR IN A DIVER'S POOR ABILITY -- NEITHER OF WHICH SHOULD EVER EXIST IN THE FIRST PLACE.
- Warren
