Let's just look at the number of things that could go wrong -- a. I screw up and the reg comes out of my mouth -- oops, I just put my reg back into my mouth and continue swimming. I don't know about you, but I was taught I could survive having the reg come out of my mouth by accident -- that, in fact, I could actually survive for as much as 30, maybe even 40 or 60 seconds without having to have a reg in my mouth. OK, that's one bad thing with no negative consequences.
Peter, whilst I agree with you that air-sharing is a relatively simple and low-risk procedure, the accident statistics do point towards this not be the case universally. What you, or I, or many/most members of Scubaboard (
a specific community that defines itself by displaying an above-average skill set, education and interest in scuba diving) find easy, stress-free and uncomplicated - may not be seen in the same light by the 'general' diving community - the 'once-a-year'ers'.
Practice is practice. Using an emergency technique for convenience to extend bottom time for a low-on-air diver, in lieu of proper gas management is not practice.
In that respect, I would isolate the issue of being 'low-on-air' as my primary concern. Sharing air in that circumstance is acceptable - for ascent, but not for a continuation of the dive.
what else could go wrong?
From what I've read and, to a lesser degree, witness for myself; panic and buoyancy complications.
From the article:
Common Causes of Open-Circuit Diving Fatalities
Emergency ascent (55%), insufficient gas (27%), and buoyancy trouble (13%) were the most common disabling agents and, together, accounted for 95% of the 332 deaths. Rapid ascent was witnessed or recorded by dive computer in over half the cases with emergency ascent, but emergency ascent also included divers who were assisted to the surface, made free ascents, or buddy breathed (Table 2). Panic was reported in about one-fifth of cases with emergency ascent, but the reason for the emergency ascent was unknown in about one third of the cases.
I, for one, was taught that sharing air is NO BIG THING whether it is in 3 feet of water, 100 feet of water or 1000 feet back in a cave. It just is -- you put your lips around the regulator and you breathe. What's "bad" about that?
1. The answer to that question is entirely dependent on the individual concerned. For you, me... and most readers of this thread.... nothing is "bad" about it. For someone else... it may be the most intimidating and scary thing they've done underwater.
2. In respect of specific issues and examples raised within this thread, the "bad" thing is that it represents an unplanned, uncommunicated form of pressure by a dive pro, to keep a low-on-air diver at depth, simply for the convenience of not having had to apply a proactive solution for ensuring that the divers under their supervision had sufficient air for the planned dive.
3. Specifically in regards to air-sharing as a diving (not emergency) technique for extending bottom time - the primary issue that I see is the potential that
a diver is low-on-air at depth. That is "bad". It is the response to a diver being low-on-air underwater that concerns me. The prudent, universally agreed, response to a low-on-air situation being to make an immediate buddy/team ascent (sharing air if necessary). Choosing to deviate from that response, to encourage the low-on-air diver to remain at depth, IS A BIG THING.
And yes -- I have shared air for kicks, I do share air for kicks and I will share air for kicks -- does this make me "bad?"
As an instructor, I encourage lots of air-sharing practice. Familiarity breeds confidence and competence. Repetition works.
In the last few weeks I taught a wreck-sidemount-tec40-tec45 combo of courses. Each of those courses included many air-sharing drills as a standard. I went beyond the minimum standard - we did a LOT of air-sharing, amongst other things. We did air-sharing until it became common-place... to the point of being boring. We did air-sharing, without warning, until the point that the student was constantly aware and prepared for that contingency. That is obviously not "bad".
However, I still wouldn't consider putting a 'real' low-on-air diver onto my gas, for the purposes of extending their bottom time. I believe that it encourages complacency in a situation that should otherwise be recognized with alarm. It encourages a sloppy mindset and the taking of short-cuts. I believe it teaches a negative lesson - where respect for gas management and the seriousness of being low-on-air is undermined.
As I said earlier, I
don't believe that there is a fine-line between practice (or for kicks) and the reality of a low-on-air scenario.
Sharing air isn't bad... but being low-on-air is very BAD.