Quote: (Originally Posted by Gledders)
...buddy drops down...
What do you do?
Descend to catch him.
Quote: (Originally Posted by Gledders)
How deep will you drop to catch him? Back down to the bottom? Are you confident that you could catch and stabilise him prior to that?
I'd drop to the depth at which I'm able to catch him even if it's deeper than the actual max depth of the dive and even if it was deeper than the MOD of the gas.
I mean normally it should be possible to catch him way before that, especially when diving with scooters.
Quote: (Originally Posted by Gledders)
Let's say you do. Will you remove the regulator from your buddies mouth when you catch him? Will your decision be affected on whether he is breathing or not...
I can see no reason to remove the O2 reg from my buddys mouth and replace it with his backgas reg. When he's not breathing, he will not breathe when he has the backgas reg in his mouth either.
When he's beathing I would strongly signal him to swap his regs. If he doesn't react I'd even go as far and pull very slightly on his reg along with the signal to change. If he still does not react then tough luck and you'll have to be prepared to have a convulsing and then unconscious diver.
If you try to remove his reg when he's breathing but your buddy is not aware enough to change regs even if you strongly signalled him to change then he will very likely not be aware enough to hold his breath while you change his regulators. The obvious result would be a completely panicked diver which is the last you need in that kind of situation.
Sure, all this has to happen very fast!
Quote: (Originally Posted by Gledders)
What then? Will you attempt any stops? Or will you get out and go on O2? Or re-descend?
Let's say he changed regs after my signal and he seems okay, aware and conscious enough to do it, I'd stay down there for 2 minutes and then ascend again with a schedule like the one I would have used if I had done a bounce dive to 60m.
If he is unconscious or did not change regs (which is the same as it is very likely that he'll loose counsciousness after convulsing on O2 @ 7.0bar) I'd go straight to the surface without any stops.
After he's on the boat you can still go down to finish deco. How much deco and at what depths would depend on the actual depth I managed to catch him at and how strongly I needed to violate the 9m/min ascend rate.
I guess 80% of the catch-depth should be enough. Stay there for 2-5min to force any of the arterial bubbles (which you may get or not from going down again, depending on the aggressiveness of the initial deco) back into solution. Then normal "bounce-schedule" (deepstops; 21m/6; 12m/2) to 6m and finish deco.
I guess the deco part really depends on how aggressive your initial deco was. If you tried to do a 35-40min deco for a 60m/30min BT dive there will certainly be enough bubbles to compress when descending, go thru the lung filter and say "hello" again on the arterial side when ascending...