@Diver0001
Thanks for the info, it would be interesting to actually do a study to figure out the susceptibility to being "narced" and the variabilities even within an individual from day to day. I wonder though, why do you feel that it is ok or safe or whatever, to do dives to 165ft all the time? By your own admission, you say if you need to be productive you would rather use trimix, what are you doing on your dives when you are using air that deep? Believe me I am not trying to put you down or back you into a corner just purely interested in the rationale behind what you do.
It would be an interesting study. As someone with a fair amount of experience with the phenomenon I would say that there isn't much logic to why you get more narced on one day than another. At least I don't personally see any logic to it at all.
As for doing these dives, I'm going to give you full disclosure and open up a can of worms in the process.
The answer is "we like it". I've been diving deep since I learned to dive in 1984. At that time, the 200ft "bounce dive" was a sort of "coming of age" in the area were I was living. From the very beginning I liked to have "a little water above my head". I never set out to be a "deep diver" and frankly I still don't see myself like that. I'm just another guy doing what I like to do. There is no ego behind it. I've made an awful lot of deep dives but there is no other reason for me to do it other than that I like it.
In our case (me and my friends) we're talking about a number of divers from the local tek community who are all highly experienced, well trained and ... even if you don't believe it ... risk aware. None of us smoke. None of us are drinkers, none of us do drugs. But we've found each other because we all like the narc.
That's the honest truth. I'm sure I'm going to get a load of **** dumped on me now but that's the truth.
As for thinking it's "safe". I can say with some degree of certainty that if safety were my only concern that I would make all of those dives with Trimix. Nothing, not even the costs, would hold me back from doing that. It's a choice. It would also make those dives a lot less "challenging".... "boring" even.
I would also be the LAST person to suggest that anyone should emulate that example. I make my choices for me. I never EVER talk about my deep diving escapades with students and I never EVER suggest that anyone should aspire to dive deeper than their own comfort zone. I have NO opinion, positive or negative, about diving with Trimix at 30 metres (which is the DIR norm) and no reservations at all in admitting that if safety is your only concern, that what we do is ... well ... kind of daft.
Nevertheless this is what we like to do. We make probably 50 or 60 of these kinds of dives a year. I've been technically certified since 2002 so you can add up how much time we spend doing this.
Is it conforming to modern "norms"? No.
Is it DIR? No. It's one of the many reasons I'm not DIR even though you couldn't see the difference if you looked at how I dive.
Is it wise? No... probably not.
Is there any reason to NOT do it? Yes.
Would I accept it if my daughter (who is a regular dive buddy) did it? Given enough time, training and experience.... yes, I would.
There.
Give me a min to put on my fire-proof undies before you reply.
R..