Sharing air to maximize bottom time.

[redacted]

OK, maybe we were just practicing. We do it when the low tank is down to 1000psi, usually during a slow ascent, so we both have sufficient gas in the event of a problem. It really is not that hard to extrapolate your training and think for yourself.

 

[InkDiver]

OK, maybe we were just practicing. We do it when the low tank is down to 1000psi, usually during a slow ascent, so we both have sufficient gas in the event of a problem. It really is not that hard to extrapolate your training and think for yourself.

Agreed. And doing what you are doing is something different. The OP asked if it is normal practice to share air to extend bottom time. What you are doing is good skills practice.

 

[texdiveguy]

We just returned from a trip to San Andres, Colombia. On the first dive out the DM shared his air with me when he saw what an air pig I was. I piggybacked with him for about 15 mins, extending my bottom time. On subsequent dives a different DM had me share with my wife, he was not much better for air consumption than me. ..........................
.......................
Is this a normal practice between mismatched air consumers? Does your dive buddy/SO share their air with you?

It is NOT normal practice to share gas except in a low gas situation were you are ending the dive.

I do not recommend you continue this practice as there are other methods of extending your bt without this method.

The DM's you mentioned IMHO both screwed up in suggesting or allowing you to do the piggybacking under the situation you described.

You might look into being in as good of physical shape as you can//evaluate cylinder size and you guys SAC rates//carry an pony bottle for contingency use only...blablabla.

But most of all don't get into the practice of gas sharing unless it is nessasary to assist in ending the dive safely, or you are just skill practicing with your buddy.

 

[JDog]

..........you should get at least 100 minutes on a al80 at 30'........

"at LEAST"..........***!!!!
Hey kid maybe you can do this now but,.........wait until you are 45 and see if you can still do an HOUR and 40 minutes on a AL80 :mooner:



Oh please tell us the most time you can do at 30feet on a AL80, ...will you be doing any swimming, or just laying on the bottom gazing at the surface in a comatos state?

 

[ianr33]

Sharing air when needed and appropriate is not asking for trouble, such as when it is needed to make a safe ascent to the surface. Practicing air drills is a good thing, and should be done regularly. However, sharing air ONLY to extend bottom time is definitely asking for trouble.

So the person with the high SAC shares off the other person and extends bottom time. A hose blows on the tank, still at the bottom, and the person with the high SAC has already sucked their tank almost dry BEFORE sharing air to extend bottom time. What do you do now??

Who said anything about sucking a tank dry? So long as you have reserved an appropriate Rock Bottom amount of gas then in the event of an equipment failure you simply do a slow ascent continuing to share air. Whats wrong with that?

I've done it before and I will do it again.

 

[Hockeynut]

If you tried this up here in the frigid cold waters of the mine pits or great lakes, sooner or later(and probably much sooner) you will get a freeflow. And there is nothing good about freeflows.

 

[micklock]

I did 121 min at 30' with double hp 80's once.

 

[ianr33]

If you tried this up here in the frigid cold waters of the mine pits or great lakes, sooner or later(and probably much sooner) you will get a freeflow. And there is nothing good about freeflows.

Then I would shut down the offending post and we would surface normally.

You do use doubles in deep cold water dont you?

 

[Vicksburg Diver]

I'd not make a practice of this. Use it up and then an emergency comes up and where are you? If you burn air that badly, run doubles or something.

 

[SkuaSeptember]

How much difference in tank size can we go? My wife is just over 100lbs, I'm around 240. When it's just the two of us, she can surface with 1500+, I'll be nearing the 500 mark. I am improving but I don't think I'll ever get near her low consumption.

Given your relative sizes and the fact that you got 80 min at 30ft which isn't horrible, I'd suggest going either with a larger tank like a 100cf for yourself, or getting an Al 63 for your wife. I have no problem getting 2 or 3 dives out of a tank to one dive for my students, but my 95lb daughter with her 63's can sometimes finish with more air than me.
As for the rest, dive lots, work on nuetral bouyancy skills,relax and enjoy! You will improve.