Sharing air to extend bottom time

[caseybird]

Has anyone seen/ experienced/ heard of an accident related to planned air sharing?

To reply to myself, obviously not.
Another SB tempest in a teapot.
Dive safe, all.

[Peter Guy]

MarkM wrote/asked

TSandM and Peter Guy, as technical divers who are obviously heavily invested in equipment, including tanks no doubt, and who are advocating (at least for well trained divers) the practice of pre-arranged air sharing to extend dive times, can you give some insight into why you chose this practice over tank size matching, if that is indeed that is the case.

Mark, I have some quibbles (actually disagreement) with your post:

a. At no time have I, nor do I believe has Lynne, "advocat[ed]...the practice of pre-arranged air sharing to extend dive times...." We accept it as a reasonably safe practice but we don't "advocate" it -- OTOH, we don't denigrate it either like (ahem) others on this thread. We merely view it as something that works in certain circumstances.

b. Why this over alternatives -- Because it is what is available, simple as that. One might get the impression from this (and other threads where the topic has been discussed) that this is a common occurrence. IT IS NOT. It is merely "an arrow in our quiver of tricks" that allows us to maximize our diving pleasure. When is it done? When the preferred alternatives aren't available. What are the preferred alternatives?

1. Bigger tank for me. Lynne typically uses about 80% of what I use so if I can have a 100 when she has an 80, everything works out fine. BUT, there are times, especially in smaller, perhaps more remote, dive ops, where that isn't an option. Then, back to square one.

2. Doubles (variation of #1). This is what we did when we dove off a GUE boat in Palm Beach -- we dove double 80s. This gave us plenty of gas and again, no problem. BUT, "in smaller, perhaps more remote dive ops" or where we have been somewhat limited on gear, this isn't an option. Back to square one.

3. Dive a stage. Haven't used this option (yet) but may for an upcoming trip to Mexico since all we'll have are 80s. Taking a stage kit and rig isn't a big deal and will give us lots of bottom time so this may well end up being the preferred option. [Note -- this wouldn't seem to satisfy one of DevonDiver's objections in that, IF we did this in a "mixed group" (i.e., with "typical vacation divers") they might be getting the wrong idea that using a stage is OK and then DevonDiver would tell me I needed to write up a Distinctive Specialty and ask PADI to allow me to teach a "How to use a Stage as a Recreational Diver" course! (Sorry Andy, couldn't resist.)]

Honestly, one doesn't need to be a "technical diver" to be able to have a non-eventful air share -- at least one shouldn't need to be a technical diver for this! Any properly trained (and I say that with tongue partially, but only partially, planted in my cheek) Open Water diver should be able to comfortably share air and swim around with a buddy. By the way, ALL of my Open Water students have done this -- that is, swim around while sharing air -- since they have to do an air share swim for 60 seconds in the pool. And before someone asks, no, they are not "locked in an embrace" when they do this -- they are in touch contact and swimming side by side since I think it is stupid to try to swim for 60 seconds "locked in an embrace." And if there are any PADI standards police patrolling here, oh well!

[markmantei]

There are many situations where tank size matching is simply not an option. For example, travel and short fills.

Agreed, and as I said early in this thread, I'm not opposed to this practice with buddies with prior discussion, just opposed to the practice of DM's doing this to extend dive times unneccesarily. The question was specifically for TSandM or Peter Guy. My assumption from their posts was that this was a routine practice for them, even given that they COULD tank match (excluding travel diving where everyone is stuck with AL80s for example).

---------- Post added ----------

MarkM wrote/asked

Mark, I have some quibbles (actually disagreement) with your post:

a. At no time have I, nor do I believe has Lynne, "advocat[ed]...the practice of pre-arranged air sharing to extend dive times...." We accept it as a reasonably safe practice but we don't "advocate" it -- OTOH, we don't denigrate it either like (ahem) others on this thread. We merely view it as something that works in certain circumstances.

Thank you for clarifying your position(s). Maybe it was just me, but I had the impression that this was something that was done routinely, as opposed to a "trick" that was employed when neccessary.

[dumpsterDiver]

I guess my reaction to "this must be an advanced skill, because novices can't do it" is that, rather than deplore the practice, perhaps we should get people's skills up to where they can swim sharing gas without stress? I will admit that this is simply NOT a feasible practice on a standard regulator hose setup. The reason it works for us is that the 7' hose allows comfortable swimming side by side.

I have a short hose and I do it with my son. I breath from the Air 2 and he uses my short primary. We can't swim side by side, but he swims above me, keeps one hand on my tank valve a can ride above me. This gives him a good degree of control although I can not see what he is doing, but I can hear his breathing well, so I have some feedback. Plus we are very close, so we can talk and scream to (at) eachother.

So not only can "regular" people do it, but they can use "regular" gear to share air. I honestly think it makes us safer in that the air sharing and the use of the AIR 2 is good practice..

[TSandM]

A lot of the places where we travel only offer one size of tank, and often, that is the ubiquitous Al80. For very shallow diving, it's fine, and we don't share gas. If the dives are deeper, a few minutes of gas sharing early in the dive will allow us to get a good, full hour's dive.

I prefer other options, where they are available. At home, Peter dives 130s and I dive 100s. Where we CAN, we dive doubles (one of the reasons I love the Tala in the Red Sea is those lovely, long, leisurely dives on double 80s!).

The gas sharing approach is purely for low-intensity, open water dives in areas where there are no bigger tanks available.

[supergaijin]

How deep are these dives you're doing?
Again, I can't see how a truly experienced diver would even need to air share on a recreational dive. On air NDLs, 20mins at 30m shouldn't be something requiring air sharing IME.

[DevonDiver]

2. Doubles (variation of #1). This is what we did when we dove off a GUE boat in Palm Beach -- we dove double 80s. This gave us plenty of gas and again, no problem. BUT, "in smaller, perhaps more remote dive ops" or where we have been somewhat limited on gear, this isn't an option. Back to square one.

A lot of the places where we travel only offer one size of tank, and often, that is the ubiquitous Al80. For very shallow diving, it's fine, and we don't share gas. If the dives are deeper, a few minutes of gas sharing early in the dive will allow us to get a good, full hour's dive.

S.I.D.E.M.O.U.N.T

It enables every remote 'beach shack' dive center to supply the requirements for you to dive with double tanks.

No skimping, shortcuts and compromises required.

[Note -- this wouldn't seem to satisfy one of DevonDiver's objections in that, IF we did this in a "mixed group" (i.e., with "typical vacation divers") they might be getting the wrong idea that using a stage is OK and then DevonDiver would tell me I needed to write up a Distinctive Specialty and ask PADI to allow me to teach a "How to use a Stage as a Recreational Diver" course! (Sorry Andy, couldn't resist.)]

I hope that was tongue-in-cheek.

I did try and explain earlier - perhaps not sufficiently eloquent in my script - that I consider the use of advanced techniques to be fine, even in the company of novice/inexperienced divers. The difference being that you can substantiate the 'heritage' and 'authority' of that technique within a formal system of dive education.

I am fine with explaining to novice divers how I am diving (doubles/sidemount), why I choose that option... and where I got those skills and experience from (training).

I am fine with recommending to novice divers how they can pursue acquisition of such training and skills themselves, through a definable course of progression, experience and appropriate training.

I would not be fine with trying to explain to a novice diver that the techniques I used were improvised, not available to them through any training course, and not generally accepted by any of the scuba agencies.

For instance, the PADI Tec40 teaches that the use of 'single + stage' is an appropriate technique for extending bottom time - even to the extent of using dissimilar gasses in those two cylinders. So... there's no need for a "How to use a Stage as a Recreational Diver" distinctive specialty - that training already exists... and you can educate a concerned/interested novice diver on how and where to access that training/capability for themselves.

My point was that you couldn't provide such education/recommendation in regards to 'air-sharing to extend bottom time'.... it has no 'heritage' or 'authority'.

Even then..... S.I.D.E.M.O.U.N.T.

There's always a solution, that doesn't involve taking sloppy short-cuts IMHO.

[t4e]

i have to thank everyone for their input on this thread, i sure am glad i started it, even though i have not made many replies in it i have read every single reply here and i have to say that its been an eye opener
i have to reiterate that the simple fact of sharing air with the DM did not cause me any distress, in fact it was quite comfortable and if it wasn't for being worried that my husband was in the same boat as me for air levels and not knowing ahead of time that this was an option, it would have been no problem at all
thankfully the whole thing had a good outcome and i have the luxury of looking back on it as a successful exercise, because we didn't really practice it before
we haven't really practiced air sharing during training but we did go through an exercise of switching gear
i now have learned that this should be one of the things we discuss as part of the dive plan, even if the DM does not cover it

at an average of 54ft dive what is the average time that a diver with good air management will get out of a 3000psi?
i realize that it also depends on body built, just want to get an idea

[dumpsterDiver]

As a dive guide, we would normally schedule a 55 ft dive for 30 minutes, maybe 35 minutes.... Most people could do that dive on a single 80 tank, without trouble.. probably 5% would have to head up a little early.

A diver with a low SAC could get 45 minutes (or more), but you need to remember to leave enough air in each tank for BOTH divers to share one tank on the ascent (if there were ever an emergency) ..

[t4e]

As a dive guide, we would normally schedule a 55 ft dive for 30 minutes, maybe 35 minutes.... Most people could do that dive on a single 80 tank, without trouble.. probably 5% would have to head up a little early.

A diver with a low SAC could get 45 minutes (or more), but you need to remember to leave enough air in each tank for BOTH divers to share one tank on the ascent (if there were ever an emergency) ..

the first dive of that day we were down at an average of 50ft for 40 minutes and after the 3 minute safety stop we got back on the boat with 500psi, i guess that's not too bad for new divers (this was my 10th)