Have you ever gone into your third "third"?

[LCF]

I read a lot of discussions about gas planning for this and that, and under those cirumstances, or with these buddies. I think we all try to be reasonable and conservative, and the fear is that even diving thirds is too aggressive, if you have a catastrophic loss of all of your gas at the turn point.

I'm just a baby cave diver, having been at this for five years, and only coming up on about 100 dives past Full Cave. But I have never dipped in my reserve gas for anything, not even 50 psi. I've carried a lot of gas in and out of caves unbreathed (thank goodness I only pay for what I use!). So I wonder a little when people start adding even more conservativism to the guidelines I was taught, and I think maybe I need to hear some stories.

So tell me what happened that made you use some of your reserve gas. Lost? Equipment failure? Medical issue?

[tflaris]

Paul Heinerth told me a story where they were doing a circuit at School Sink. The tunnel collapsed and the divers where forced to return the way they came. One of the divers went into his last third.

Forrest just posted about a broken line at Hart.

Stuff happens.

[jxh2297]

Alot of times ill mess around in the cavern, take pictures, do air sharing drills, on the last 3rd for about 10 mins.

[JamesK]

Yes. Silt out that caused the exit to take a little longer then planned. That's when I quit diving thirds.

[jcook]

Yes. Silt out that caused the exit to take a little longer then planned. That's when I quit diving thirds.

+1 for that. Then I got into deco on the dive and ate 400 psi out of my reserves.

On the flip side of the coin, dive to what you are comfortable doing. If you want to stick with 1/3, then go for it, you will probably never have to deal with using the full reserve. But there might be that one dive where you do.

[Puttzer]

Yes. Silt out that caused the exit to take a little longer then planned. That's when I quit diving thirds.

Shared air exiting the Crypt at Peacock. Now typically end my dives with half my air left.

[scububa]

Yes. Silt out that caused the exit to take a little longer then planned. That's when I quit diving thirds.

By definition

sorry, couldn't stop myself.

[LCF]

Puttzer, how did that happen? That's the kind of thing I'm curious about.

And BTW, I'm not looking for ammunition to stop following the rules I was taught. I'm looking for cautionary tales to make me more careful.

[Jay]

A working dive in a very high flow cave. Got the deed done and bolted for the exit.

[Jay]

Oh, and a LP hose failure on exit put me into my last third once on SM. Reasonably close to the exit in a high flow cave though.