MSilvia:I can't say I agree about your gas management, but I wasn't asking about that... if anything I was asking about your experience with donating a long hose while wearing a snorkle, and how it is you avoid entanglements while doing so. As far as I can tell, everyone who mentioned snorkels as an entanglement hazard is either doing wreck penetration or diving a long hose, and you said that despite what we all think, it isn't so. I'm curious how you come to that conclusion.
Perhaps, so long as nothing goes wrong. That's maybe not such a good thing to count on though. Suppose you buddy had an equipment failure late in the dive and it was he who needed you to share air? Suppose after you surfaced, you lost a fin? Sure, everything worked out okay, but with 100psi 1/4 mile from the boat, you didn't leave much of a safety margin... even if it was shallow water. I'm glad to hear you don't make a habit of it!
I don't use a long hose, have never even considered such a thing. I don't do wreck penetration, just doesn't really interest me. I'm more into critters than scrap metal, maybe comes from working with metal for 31 years (I'm a machinist by trade). I was in more danger of drowning from laughing so hard at the antics of those sea lions than I was of running out of air.
To respond to your other questions, at 15 feet, it's not really that difficult to do an OOA ascent, even on 100 psi. And my dive buddy is my wife, who is a former instructor and has been diving 5 years (and about 500 dives) longer than I have. 20 feet of water is normally just free diving for me anyway, so should I run out of air (which I never have), it's a simple ascent while exhaling. And as for as the 100 psi 1/4 mile from the boat... that is exactly why I wear the snorkel.
When I'm on a dive trip, which is the only way I dive any more, I practically live in the water, either diving or snorkeling during my SI, or snorkeling from shore after the boat dives. Thus, doing a surface swim with my snorkel just seems like a logical choice for me.
BTW, this is NOT something that I would do on a normal dive, where a safety stop might be indicated. I really am a pretty good diver under the conditions which I choose to dive. I would never question your snorkel decision in regard to a long hose, because I have never used one. Nor would I ever offer any negative comments toward any type of diving that I don't have previous experience with.