How far from the buddy is an easy one...
String, I love you, man! Everything seems so simple and easy for you. My point is it takes a considerable amount of work to determine what the right distance is.
...todays gear is pretty darn safe...
My hammer is very safe until I pick it up and smash my finger with it. Thanks for beginning the discussion. This is one of those things that many of us take for granted, or don't really think about.
The thing about "how far you can swim on a lung full of air" is that you have to remember that it really should be "how long can you swim on a lung that is empty of air".
Rather, shouldn't it really be, "How far can you swim on empty lungs and still have enough time to survive while you get your buddy's attention and get their reg in your mouth?"
...Try breathing out and see how far you can swim in full scuba kit sometime, ive tried it and i didn't get very far...
We tried it tonight, see below.
... I have done the experiment of exhaling, pretending I'm out of gas, and swimming to an otherwise distracted buddy, and I found that 25 feet is as far as I EVER want to be from my spare gas. So 25 feet is the MAXIMUM I'll get from my buddy
That's at least twice, and probably closer to five times the distance we came up with tonight. However, considering the fact that you are at least twice, and probably closer to five times the divers we are, not surprising. Nevertheless, well, see below.
...and that is only in calm water with superb visibility. If the water is moving, it gets harder to reach that breathing supply, and if the viz is low, 25 feet might be quite enough to lose one's companion completely.
This reminds me of something somebody said at work the other day, "If it isn't written down, it didn't happen." If you've lost your buddy completely, you have no buddy. I know that's not what you meant; you meant that in bad viz 25 feet is too far. You have to adjust the distance for the conditions, as many in this thread have said.
Remember this is why we check the contents gage during the dive to avoid running out of air
You seem to be missing the point of, "This is why we train for the worst-case scenario." Of course we check our gauges to avoid an OOG situation, but if the worst case is something we absolutely want to avoid, then it makes no sense to rely on something that might not have happened.
Yes because checking a contents gauge will completely eliminate the risk of a hose blowing, burst disk (in countries backward enough to use them!) blowing, a HP seat going, a reg diaphragm breaking or any other mechanical fault......
That's right, I love you, man!
Things can blow on the surface or underwater. Yes hoses tend to go when first pressurised but not all the time. Thinks can bream at any time, usually when you don't want them to.
Also, contents gauges can lie and jam as well.
Exactly.
Wouldn't the initial presser from first pressurizing the system have more effect then at depth and after some of the air volume has been used up?
This would support the reasoning behind having your contents gage serviced annually,
Don't rely on assumptions of what should be. When the defecation hits the oscillation you'd better be ready, and then you can figure out what happened and why when you get back on the beach. Your posts on this thread give me the impression that you might benefit from a large dose of skepticism. That gauge that you had serviced annually could kill you. My advice could kill you. Be careful! Believe nothing! How can you relax and have fun if you don't have all your shXX covered?
If you want practice, try using the miflex HP hoses. These let go often enough underwater to give you plenty of practice recognising and dealing with the problem
String, I've been curious about the miflex hoses, including the HP. Have you ever seen one of those camp saws that is basically a piece of wire with another wire wrapped around it and two rings on the end? That's what those HP miflex hoses remind me of. They may work, but they's destroy everything else around. And then here you are saying they don't even work? Please add more info about this, either here or PM me.
My buddy and I based our dive today on this thread. Our exercise was this: we descended to about 15', stabilized, one of us went as far away as we thought we could do this, then, when both of us were ready the subject exhaled and swam to the... object? anyway the other diver, and we did an OOG air share. We started at a distance that we thought we could succeed at, and kept reducing the distance until we could actually get it all done. It turned out to be shockingly closer than we expected. A real eye-opener.
All I can say is I strongly urge everyone reading this to try it yourself next chance you get. You won't know for sure what the distance is until you do. And then, once you know what that distance is, how can you justify going beyond it?