Question on 3rd's

[victorzamora]

Also in high flow caves, e.g. Ginnie, if you have low/zero vis and need to stay on the line, you're not always in a good flow position at all. In many places the line takes you through Eddies that can be very annoying to kick out of.

The more I dive, the more I realize that flow isn't easier....it's just a different challenge. On an exit under "good circumstances" a high-flow exit (Ginnie/JB/LR) makes life easier on my knees. Many of the issues I encountered during training were actually due to the flow.

I have to say that I've never heard anyone admit to breaking thirds before, this is certainly a premiere.
Would you mind sharing your name with us so we don't risk being teamed up with you by accident?

I think this emphasizes the "instabuddy" thing. Before you dive with an instabuddy, make sure they're up to your usual standards in terms of ideology, and discuss the dive plan first. I was an Intro diver planning a dive with a Full-cave instabuddy when I got my first taste of needing to get on the same page first. I expected a dive to sixths, he expected a dive to thirds...we cleared it up at the surface, but had he have pushed back I would've scrubbed the dive. I've planned dives with people far less conservative than myself but have yet to scrub a dive because of it....I simply state that I am not comfortable and need a wider margin. If that doesn't clear things up, I'd scrub it....but I've never had an issue.

bullfrog, are you SM or BM? Do you primarily dive in a team, with a buddy, or solo?

[cmint]

Maybe you should ask Agnes how well this worked for her in Ginnie when she was borrowing random stages to get her ass out.

Oh wait, you can't...

I would like to hear this story too.

The thought of grabbing someones stage to get out is scary.

[bullfrog]

natakomi Have you dove till thirds in peacock? victormora. I am sidemount, I have a buddy. I have not soloed in a cave but have a couple hundred solo dives in open water. Agnes died with only one tank. I still think breaking thirds in Ginnie, by 200 -300 psi is safer than doing thirds in Peacock.

[Jack Hammer]

To me, that means a cheaper gas fill....not that I wasted "penetration potential."

I used to think flow was all good and helpful, but there was a story on here that scared me straight where a roll-off caused the diver to think he was OOA and the flow played a part in blowing him off the line....but I can never find it when I need it.

That was Andrew Ainslie (Aainslie) and it was in Ginnie. He was lucky to make it out. He made a nice write up on it and posted it in pdf on his site. His entire demeanor changed after that. I have the file some where if you don't find it.

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[victorzamora]

natakomi Have you dove till thirds in peacock? victormora. I am sidemount, I have a buddy. I have not soloed in a cave but have a couple hundred solo dives in open water. Agnes died with only one tank. I still think breaking thirds in Ginnie, by 200 -300 psi is safer than doing thirds in Peacock.

What's interesting is that I almost agree with the bolded section. I'd reword it to: "I think diving to full thirds in Peacock is just as unsafe as breaking thirds in Ginnie by 200-300psi." I know it seems pedantic, but I think that's the difference. I think Peacock is a bit of a unique situation as it has so many potential exit points, and few passages are actually getting absolutely farther from an exit (distance tunnel is about the only one I can think of). However, in caves with similar flow but less exits (Twin Cave or Hole in the Wall are both nearly zero-flow and don't have additional sink holes)....I don't dive to full thirds. I'm usually a few hundred psi short of thirds in those.

[Jack Hammer]

natakomi Have you dove till thirds in peacock? victormora. I am sidemount, I have a buddy. I have not soloed in a cave but have a couple hundred solo dives in open water. Agnes died with only one tank. I still think breaking thirds in Ginnie, by 200 -300 psi is safer than doing thirds in Peacock.

"Safer" is a relevant term. That still doesn't make it a good idea.

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[Kelvin Davidson]

I used to think flow was all good and helpful, but there was a story on here that scared me straight where a roll-off caused the diver to think he was OOA and the flow played a part in blowing him off the line....but I can never find it when I need it.

Bad day, good write-up

[victorzamora]

That was Andrew Ainslie (Aainslie) and it was in Ginnie. He was lucky to make it out. He made a nice write up on it and posted it in pdf on his site. His entire demeanor changed after that. I have the file some where if you don't find it.

Thanks....I was fairly certain it was Andrew but didn't want to put his name on it in case I was wrong. I still can't find it, so a link/attachment wouldn't hurt. I think it's one of the most terrifying stories I've read regarding cave diving but likely the best for learning limits.

Bad day, good write-up

Thanks, Kelvin...that's the one.

[shellmoundal]

Thank you so much for posting the above attached file. Lately I have been diving Ginnie solo. I dive LP85's SM. MY turn pressure is always less than 1/3. I have asked myself many times if I should have gone further back. My average dive time is 72 minutes diving solo. My average starting pressure is 3600 psi. My end pressure on the steps is 1800psi on my left and 2200 psi on my right. Adding those two together has made me rethink my dive plan. After reading the above attachment I am going to stay with my normal turn pressure.'
I agree, most cave divers think Peacock is a beginners cave when in fact the rule of 3rd's is most dangerous in that kind of system.

[nakatomi]

natakomi Have you dove till thirds in peacock? victormora. I am sidemount, I have a buddy. I have not soloed in a cave but have a couple hundred solo dives in open water. Agnes died with only one tank. I still think breaking thirds in Ginnie, by 200 -300 psi is safer than doing thirds in Peacock.

Peacock has a ton of exits, depending on the dive plan there will usually be an exit in your path that is closer to the one you have entered the system through.
So yes, I dive almost full thirds in Peacock if I consider it to be safe and the plan allows for it. Adding stages helps too because a regulator/tank O-ring failure is much less unlikely to make a significant impact.

I absolutely can't believe nobody is going ballistic in regards to the admission of someone breaking thirds. I'm pretty shocked to say the least.