Nobody really got hurt that I know of, but all of this was a confidence shaker. I don't want to see anyone have to do this stuff, let alone so much in one week.
Usually these sorts of issues don't lead to injury. Far more often they lead to people surviving just fine, thinking back on it later and realizing that scuba diving ain't worth killing themselves over ... and they quit diving.
Seen that happen many times.
Ultimately, as I am sure you would agree - all divers are responsible for their own safety. It sounds like a lot of people were not monitoring their gas consumption very well. It also sounds like a lack of communication and agreement on the second dive at Cathedral as to how the dive was to progress. Shallow water or not - OOA happens when a diver is not paying attention in most occasions.
It sounds like a lot of these people had no idea how fast they could go through their air at those depths, and only realized it when they were down there. You can monitor your air all you want, but if you go to 120 feet without at least a basic understanding of how fast you will use up your air ... or how much you will need to surface from that depth ... watching your gauge won't keep you out of trouble. You need more information than you have available to make a reasonable decision.
One DM was taking 6 relatively inexperienced divers, presumably not trained specifically for diving deep, into an overhead environment. The depth made narcosis a very real possibility and gas management a critical issue on the dive. To top it all off, I bet the divers only used AL80 tanks. Based on info in the OP's post, it's pretty clear that the divers involved were abdicating gas management responsibility to the DM. What could possibly go wrong?
Therein lies the biggest problem with "trust me" dives. By the time a diver realizes that something's gone wrong, and that the DM hasn't responded promptly, it can be too late.
@midwayman: How did your wife's low on gas situation make you feel?
After all, she is carrying your emergency reserve gas.
What might have happened if you had encountered some sort of difficulty near the end of the dive? Do you think she would have been able to help you out...or would she have had to surface due to being low on gas?
There's a lot to think about from this incident.
It is often the case ... particularly with newer divers ... that when one buddy runs out of air, the other buddy has precious little left to share. This is why one should never do a deep dive without understanding the basic concepts of
gas management. Even just knowing at what PSI you should leave a given depth can be enough to prevent things like this.
It also sounds like people weren't watching their gas. That's just inexperience being overwhelmed by the excitement and beauty of the site. Or just plain lack of attention. I got in the habit of doing a "gauge sweep" every couple minutes.
IT sounds more to me like none of these people comprehend the principles of
gas management ... and were relying on the DM to tell them what to do. A diver can watch their gauge closely ... but if they don't understand what to watch for, it isn't going to help them.
You're right. This group had no business being there. Not enough planning, not enough real self-assessment of skills. We were lucky something worse didn't happen. Even though it was quick up and down it was close on gas on an AL80, and close on the NDL even on a computer. It didn't help that the DM talked the whole thing up as "easy" etc. I'm not happy about being taken to devil's throat despite explicitly being told we didn't want to go there.
I'm sure it's an easy dive for the DM ... he probably goes there several times a week. But if the group is expressing concerns about going, he shouldn't have gone. On the other hand, this is one of those times you need to stand up for yourself ... the decision to go on the dive anyway was yours and your dive buddies to make.
Sigh... air monitoring is the certified divers' responsibility. A dm leads the general direction of travel as far as I'm concerned. that's it. depth, time, air is MY control. These near OOA or OOA posts are making me think....if YOU run ooa you deserve to. And to "ask" the DM "I'm OOA?" TELL the DM I'm low-on-air/OOA GO UP! I can't understand people not taking control of thier own dive. I'm mean seriously you are going to "trust" some DM punk who parties it up in Mexico with your dive decision? Your family? Your Life? Never Never Never. A spg is not that complicated people.
There's more to it than watching the spg ... particularly for the newer diver. They haven't gotten enough experience yet to make good decisions. Peer pressure, narcosis, and a lack of information create the "perfect storm" for decisions that lead people into bad places. These people are counting on a DM to lead them up ... if the DM doesn't respond promptly, I'd bet you none of this group had the skills to conduct a mid-water ascent in current with anything close to control. Bet ya none of them had an SMB ... except the DM ... or knew how to use one even if they had it.
Maybe half were uncomfortable and expressed they didn't want to do it beforehand. We had told him that we had decided on Cathedral as a group.
Did you know beforehand that he had overruled your request, and was taking you to a place you had already told him you were uncomfortable with? If so, then you SHOULD have simply said "no thanks" and stayed on the boat.
Yeah, it's hard to do that on a vacation where you're paying a lot of money ... but it's a lot cheaper than a chamber ride, or a funeral.
Yes, 120 is deep. AFAIK I was the only one with deep diver training. It wasn't a training dive. A couple of them had asked about my AOW training earlier that week. One couple seemed very experienced, but only had BOW. The second one I couldn't say either way. Typical vacation divers I suppose. The last one (the OOA one) I got the feeling he was pretty new.
Did your training include
gas management? If not, then you were not qualified to do this dive. And if it did, you should have known better than try it on an AL80 ... it simply doesn't give you adequate reserves ... particularly when diving with someone fairly new, who will most likely have a pretty high consumption rate.
I believe that gas management is in general very well understood.
I don't think it's very well understood at all. At no point in my recreational training was it even taught ... and that includes training up through the instructor level. The vast majority of instructors I know don't understand it very well ... so they bloody welll can't teach it. For the most part, experienced divers keep themselves out of trouble because they've done enough dives to know by looking at their gauge when it's time to come up. But they learned that by doing it hundreds of times. The newer divers don't have that advantage. Telling someone to "begin your ascent at 1000 psi" is about as useless as telling them to "end the dive with 500" ... because unless they know what their consumption rate is, as well as that of their dive buddy ... they have no way of knowing whether or not that's an adequate amount. This is PARTICULARLY true when on a dive that takes you through an overhead to 120 feet.
Gas management was taught to you by your instructor when you were brand new to scuba.
Gas management in most OW classes consists of "watch your SPG" and "end the dive with 500 psi". That is not gas management ... it's a couple of rules of thumb that are only helpful if you know what you're watching for. AFAIK, not a single mainstream agency takes gas consumption measurements at the OW level, or trains their divers how to use those measurements to determine a rock bottom pressure for a given depth. Unless you know what psi you need to begin your ascent, watching your gauge doesn't really give you enough information to be useful.
You viewed that instructor as an authority figure. You are still new to diving, thrilled to be hitting the sites in Coz. You are being led by a DM who might only have 100 dives, but that is ten times the number of dives that you have. The DM becomes another authority figure to you. Part way through the dive you signal the DM that you are low on air. The DM wants everyone to have a great dive, so he stretches it out a bit. You get lower on air. The DM finds an octopus and passes it around. You are beginning to hyperventilate. Why haven't you called the dive? Because the DM is an authority figure, you don't want to be a bother, and that DM must know what is going on... Plus, by the time you figure all of this out, you realize that you are no longer able to complete a safe ascent without someone else's air.
You're at 120 feet. You are getting low on air. You may even know that you're already too low to make an ascent without assistance. Add to that the fact that there's nothing but water and current between you and the surface. You've never done a free-water ascent in your life ... you don't even know how. You're scared. The DM isn't responding to your upraised thumb. You glance down at your buddy's gauge and he's just a hairline above the red zone.
What do you do? You've put yourself into a bad place that you are in no way prepared to get yourself out of.
Welcome to a "Trust Me" dive ... have a nice day ... :shocked2:
Of course it is your responsibility to manage your own air. Often I fear that a lack of assertiveness and not lack of air management skills is what gets new divers into predicaments.
Yes ... but there's a natural tendency to assume that the DM knows what he's doing. There's also a natural tendency for people to assume that their skills are better than they often prove to be. Both of these are significant contributors to bad outcomes in the sort of situations the OP described ...
... Bob (Grateful Diver)
She probably should have gone up but had 1500 PSI 30 minutes into the dive and didn't want to. So she hung around folks with LOTS more air the rest of the dive. 
