Another "what would you do if..."

[DA Aquamaster]

Here is a scenario based on a past dive that prompted me to consider various options. I am interested in what other cave divers may have done in that situation.

A team of four divers in PIII. The team takes the first jump, jumps back to the main line just short of the Hendley's Castle jump and then takes the jump to Hendley's Castle. Since the mix was in the 32% range (two divers had 32%, two had 30%) the plan was to proceed on the line toward Hendley's Castle with the goal of showing two of the divers essentially where it was to a depth no greater than 110' (roughly the mod for 32%), then turn the dive and exit along the entrance route picking up the 3 jumps that were placed.

All goes according to plan for most of the dive with some minor delay finding and making one of the jumps. However, on the line to Hendley's at the 110' mark and near the turn pressure, one of the divers (on 30%) continues down the line, one diver remains at 110' (at the MOD) while two other team members descend to 120' to duck under a ledge to better be able to beat the diver up with light signals to turn the dive and get a better view of where the diver is going (one of these divers is on 30% at a PO2 of 1.4 at 120' and the other is on 32% and at a PO2 of 1.48 ). However the wayward diver continues, dissappears from sight and is gone about 4 minutes with no lights in sight. The three holding divers are now essentially at or near their turn pressure.

Assuming you are one of the divers holding at 120', what do you do at this point?

1. Wait longer?
If so how long?

2. Go after the possibly incapacitated diver, even though doing so puts you well below the MOD of the gas you are on?
If so, how far?
How long?
How deep?
(Consider also that the depth below about 130-135' will involve moving through a low but wide and somewhat silty restriction at 135' for at least 2 minutes before you could further reduce your depth and PO2.)

3. Leave the diver and exit the cave, leaving the jumps in place?

4. Something else?

[sskasser]

For starters, I would hope he survived so I could beat the crap out of him.

[LiteHedded]

I'd dip into my reserves a little and go down to the bedding plain to look for him.
This would probably be my last dive with this person.

[J_glenn06]

I would turn the dive! But i would leave all the jump reels just in case he turned when we did. I'm a little pickey when it comes to thirds so some people might push it and wait but once i hit thirds im signaling and gone.But like she said if he lives thats the first time you will ever see me in a drysuit beating the hell out of someone.

But this leaves me with a question. PIII is a siphon correct?(never been there). I was under the impression that you would not go to thirds if you were in a siphon. So should the teams have turned the dive before they even reached there mods?

[LiteHedded]

It's a slight siphon. My turn pressure would not be thirds on that dive.

[jj1987]

That gas isn't only there for a reg failure, it's there for other things (like this), too. Violating the MOD by .08 ppo2 wouldn't be a huge concern for me if it was to save a buddies life.

Post dive, I'd break out the Gospel of GI3 and read Ch1, Rule #1, as it's relevant here.

[FW]

If anyone went down after him, it should be a diver on 30%. The 32% guys should go back to a shallower depth to wait. Remember that at one time, 32% was dived to 132', but some people did tox at that depth.

Abandoning a diver when you hit thirds is not taught by any agency. You are supposed to wait, or look, as long as you safely can. You still need some reserves, in case something else happens, like the slit you are bound to stir up in that tight tunnel.

An important issue is wether you have O2 waiting at the entrance. If you do not, you need to reserve some gas for deco, that you probably didn't expect on your original dive plan.

When/if you have to leave him, you should absolutly leave the jump reel to the goldline in place, but remove the ones to the side circuit, so he doesn't go the long way out.

[atedeschi]

Why not just have the person with the same mix, go and signal him? Gas realy is not much of an issue since you had a 4 man team, tons of extra gas. I assume the person who kept swimming was not at turn pressure yet, so the person catching him might have been past theirs but, get there attention turn and hull ass out if need be. I def would have to talk to the person after and be ask what they where thinking or if they misunderstood the plan, etc. The big thing to remember I believe is there was plenty of gas assuming you all were right at or just past your planned turn, because you had four divers.

[aainslie]

Were you SM or BM? That definitely changes things. Let's assume BM

You had a group of 3 people intact. With this group, you can go WAY below thirds and still survive the catastrophic loss of one person's gas.

I'd wait right there for another 300 PSI which effectively means "using" one of the thirds between you. Then I'd turn and exit. You still have enough gas between you to exit one diver OOA safely.

And after exit, I'd let the person know that they're done diving with you.

[alias]

Just curious - was the person who trucked ahead one of two who was showing the cave for the others or one of the two who knew the cave less?