but take an OW into an overhead environment and he has absolutely no trained strategy or skill set to get himself out of trouble.
The problem with this is that the OW diver is already in the overhead environment. None of the cavern dives begin in the overhead, they all start in open water. The personal responsibility aspect needs to come into play BEFORE the diver looks up and can't see the surface. There's no need to thumb the dive inside the cave, because they shouldn't be there to begin with. That's their responsibility and only their responsibility. I could give you twinsets and double stage and say we're gonna swim from The Pit to Dos Palmas and it would be your responsibility to call full stop. Just because I"m trained and capable of doing it, doesn't mean it's my responsibility to make smart choices for you. I may be an idiot for inviting you along knowing you're neither trained nor capable, but that's a different issue entirely. (The global you, not you specifically
@Phil_C ) People think "trust me" dives absolve them of responsibility, whereas the opposite is true. It's never anyones responsibility but your own to stop doing something dangerous, especially BEFORE it gets to the point of danger.
And ignorance isn't a good answer. EVERY OW course says to stay out of the overhead. Every single one of them. OW divers know better, they're just ignorant enough to think that a trust me dive means someone else is gonna hold their hand and that their training should take a back seat.
Honestly, and this is just my opinion, they shouldn't have a training strategy to get out once they thumb the dive, because cave diving is one of those situations where a little bit of knowledge is far more dangerous than a lot of knowledge. It lulls people into a false sense of security and they think, "oh I know what to do if something goes wrong, I'll just peek around that rock over there." Then they die. Or even worse they survive a couple of these then they really think they're awesome, then when they die they put others at risk to get them out, or they take other people in with them and they die too. There's a reason that cavern, intro, and full cave are split up and it is a progression where new skills are introduced along the progression. Going from AN/DP to hypoxic trimix is no stretch, the procedure is the same, gas switches are the same, everything is the same. There's certainly a knowledge and experience curve, but there's nothing comparatively new. In cave diving, when there are strict limitations in terms of things like navigation (cavern can't navigate, no jumps, gaps, t's, anything), diving 1/6ths instead of 1/3rds, etc., it's harder to get into a situation you're not equipped to deal with because the very nature of your training limits you, provided you are responsible and dive within your training. One of my very first training dives there was already a team in the cave, they jumped from the mainline, I turned the dive because I'm not allowed to make navigational decisions and that was a navigational decision. If I were an OW diver that had just a touch of knowledge, I'd think it was no big deal, instead of realizing just how potentially dangerous that could have been.
So the bottom line is that people need to call the dive before they're in a position where they need the training in order to thumb the dive. You should NEVER need specialized training to thumb a dive. But like I said earlier, Hans from Stuttgart doesn't care, he just wants to see some cool cave, get burned on the beach, and maybe make googly eyes at a local girl And there are plenty of people willing to take his money and hope he doesn't do something stupid, because most people don't do something stupid like do a visual jump to the cave line then die. Unfortunately some people do, and we read about them here.
So Phil, I'm not disagreeing with your post, but I think you need to think even further before that. The call needs to be made before the OW divers are in any kind of overhead. The diver needs to decide before thumbing the dive is no longer an option, because as you said, once in the overhead, it's not really an option.
And how did Angelita make its way in here? Angelita and Calavera are two completely different cenotes and different environments.
