Have you ever gone into your third "third"?

[Puttzer]

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.

The short version: buddy was acting confused during the dive. He grappled my reg just after coming out of the crypt. I knew I had the air for both of us to get back if we got going and didn't mess around. So we just took off tothe main line where our travel bottles were. There was no real emergency. His isolator was closed and he couldn't reach . Never considered that a possibility at the time.

[AMW]

Back in the 1980,s myself and another divers were working beyond a few sumps digging an underwater boulder choke (in the third sump). On one dive we opened up the choke so the other diver passed through as I was sorting out a line junction the choke collapsed! yes I know we should have secured it before passing through but the mix of youth an exploration fever over rides rationality at times (so keen and stupid). So me one side the other diver the wrong side and as far as I knew no know air space his side. So I started digging all the while checking my gauges and running the sums after a while it became all to clear I would soon have to head out or not make it out leaving the other diver stuck beyond the choke I carried on digging and luckily the choke moved again and out came the other diver. We returned to the air space an decided we could make it out although back at the surface we had not a lot of gas left not many bar per cylinder it was a close run thing. I had run one cylinder dry on the dive to base.

Andrew

[MORGAN]

I've never been into my bottom third. Been close a few times, but never into it. I'm just a line-following tourist caver with 230-some cave dives and am pretty conservative. I like to have a good big safety factor built into my dive planning for that inevitable dive where things go to hell.

[PeterVICEG]

In 1994 my partner and I were exploring a tight cave on northern Vancouver Island. Due to the tight nature of this thing we were doing all our dives solo, with tanks staged in the cave. We had recently done a nitrox course, and had various mixes and a T of O2 in the cave for our deco, but we were not using He. We were diving on air.

On a previous dive I had run out the exploration reel and dropped it. The depth was about 150 feet, and the reel about 400 meters in. My mission was to tie on a new reel and lay a little line.

I had an uneventfull trip to the back. Much of the passage is less than a meter in diameter and there are a couple of wriggle through bits, but no no mount. Of course this is all side mount.

When I got to the back I checked my gas, i had lots. I felt good and settled in to cut the line and tie in the new one. No biggy.... When done I had blown my thirds. ####, all I can think is that I was narced but good. A simple task had turned into a big deal with depth and cold hands in three finger mitts. We had been doing many dives in the 170 to 200 foot range to "get used to the narcosis, I no longer believe that works.

Swimming back and pulling through a tight spot, I got a fin stuck. All I had to do is be calm and work it out, but when I got to my staged tank I was well into my last third.

A much more spectacular event was when I was wiggling through a truly tight spot at a similar depth and knocked off my first stage. We were still using yoke conectors and the resulting high pressure burst upset the gravels that were lying at the angle of repose above the slot we had gone though, instantly buried me. Worse yet, the compromised tank was the one I was breathing on. This was one of those spots where you can only get through with one arm at a time, so I was pretty jamed up. I was with my partner who was behind me, and funnily he had no idea that there was a problem until I spurted back out and was furativily faffing about with my gear. This was when I learned that one can re-attach a first stage under water. I had turned this dive before getting to thirds. As it was we were four sumps in with three meter climbs between them, so I had lots of time to regain my composure before exiting the cave.

This past summer I was pushing a grotty little thing when I blew out the vis in the stagnet water. I was only about 80 feet deep, but as I could hardly see a thing I turned it long before thirds. As I assended a tightish chimney, I found myself in a dead end and had to sink down and pay better attention. The line fit where I could not but as I had plenty of air I hardly even got excited as I worked this through.

Exploration or following a line, I view thirds as a minimum, and almost always turn much sooner.

Peter

[chris.lisowski]

Thanks for this thread. As a newby, this type of information is great.

Thanks to everyone who shared their stories.

Christian

[RN]

Being that I don't ever dive thirds I've never dipped into the last third. That being said, I always dive more conservatively and do reserve more than a third for emergencies. while it's rare that I have to dip into the reserve I have done so by about 100 psi on a few occasions. All but two have been during exploration dives where getting back out involved a little more maneuvering than I anticipated. One involved an air share where we thought there were regulator malfunctions or bad gas involved and we had to exit on my gas. And the final one was during a fatality where we hadn't even come close to turn pressure but the exit just sucked up a bunch of air. That one sticks in my mind for more reasons than one. We hadn't even hit sixths but I still tapped into my reserve. I did keep my breathing under control but the adrenaline and extra working load of trying to perform a rescue didn't help much. We all came out with a lot less air than expected. Had this happened anywhere near full penetration it's not likely we would have made it out with the gas reserves we had.

[LCF]

Thanks, Rob. To clarify -- somebody on your team needed rescue? Or had you gone in to get someone who was in trouble?

Thanks to everybody who has posted. Great material for thought here.

[LiteHedded]

I've dipped into a reserve on an exploration dive.
we weren't diving thirds of course but the exit was substantially longer than it should have been and we were glad to have that additional reserve

[deepdiverbob]

I think I can count on one hand how many times I have hit thirds, usually turn before thirds. I like to plan my dives on reaching a certain point, and turning it there. Of the few times I have hit thirds, I think they have been either at Ginnie or Little River, where I knew the flow would make up any potential lost time.

[RN]

Thanks, Rob. To clarify -- somebody on your team needed rescue? Or had you gone in to get someone who was in trouble?

Thanks to everybody who has posted. Great material for thought here.

Somebody on the team. This was the Cozumel incident in October 2011.