Max. depth on Air

[DA Aquamaster]

I read an interesting article recently on the effects of narcosis and to keep it short, the experiment involved groups of test subjects all of whom were new divers and some of whom were told that narcosis was a serious problem and very incapacitating and others who were told it was no big deal.

Surprisingly, the "narcosis is no big deal" divers performed quite well on various mental tests at deep depths while not surprisingly the group conditioned that narcosis was very incapacitating were in fact very incapacitated and at relatively shallow depths.

So it would seem to some degree that narcosis is what ever you expect it to be. In my opinion, the effects of nitrogen narcosis involved in diving deep does require additional focus on a task to perform it effectivley and at the same time you need to guard against getting tunnel vision so to speak. dealing with it is very much a matter of being able to focus and alternatively to maintain the ability to divide your attentioan and prioritize effectively. There is some degree of motor coordination loss that occurs at depth on air, but I think tolerance to nitrogen narcosis is something that can to a large degree be learned.

I also think that the ability and experience to be able to manage the little things on a dive (bouyancy, keeping track of air pressure, etc) are important as if these functions are overlearned and essentially ingrained as automatic responses, it frees additional mental resources to deal with novel or unexpected situations.

 

[Braunbehrens]

rdriver once bubbled...
I have been doing a lot of dives at 150 feet this summer (deco procedures and entry level trimix) I know that some dives that I have been narced out of my gourd and others it's been OK..... Why?..... because I guess they want to see how we react to deep "air" before we start our trimix class.
Rob

Hi Rob.

This kind of teaching has pretty much been debunked. There are many many discussions on this, and it has gotten so far that even the agencies that used to require deep air before trimix don't anymore.

I would say that any instructor that still teaches deep air is not someone anyone should learn anything from.

I realize you don't know me from Adam, and have no reason to listen to what I say. For this reason I suggest you do some research on this issue. This kind of diving is quite dangerous, and learning from someone whom one respects but who is no good can have fatal results.

One argument against Deep Air before Trimix is the analogy of driving. Would you teach someone to drive drunk before you teach them to drive sober, so they "know what it feels like?" Clearly not.

I'll shut up now, and I hope you don't take this the wrong way.

P.S. I don't know what my deepest air dive was, I suspect about 80 fsw. These days I never dive air unless nothing else is available, and if this is the case I will limit my diving to very shallow reef dives (i.e. less than 60 fsw).

I usually use trimix 30/30 for anything above 100 fsw or so, and below that I use 21/35 trimix.

 

[DA Aquamaster]

Braunbehrens once bubbled...
I usually use trimix 30/30 for anything above 100 fsw or so, and below that I use 21/35 trimix.

Just curious... (I live in the sticks and don't have access to trimix. I'd also love to take a trimix class but would have to drive across 2 states to do it.)... how many dives per year do you do and what is the cost per dive with trimix?

 

[Charlie99]

DA Aquamaster once bubbled...
I read an interesting article recently on the effects of narcosis .....the "narcosis is no big deal" divers performed quite well on various mental tests at deep depths while not surprisingly the group conditioned that narcosis was very incapacitating were in fact very incapacitated and at relatively shallow depths.

So it would seem to some degree that narcosis is what ever you expect it to be.

I also think that the ability and experience to be able to manage the little things on a dive (bouyancy, keeping track of air pressure, etc) are important as if these functions are overlearned and essentially ingrained as automatic responses, it frees additional mental resources to deal with novel or unexpected situations.

What article was this?

Has anybody seen any studies that shed some light on the "O2 is/isn't narcotic" question?

 

[Charlie99]

My deepest on air was 143', in near perfect conditions of 200' viz and 79F water, for no more than about 5 minutes total below 120'. It is not a dive I repeat often, not because of narcosis, but because I dive single tank, single first stage.

With a single tank, at 80', I'm content to poke around in reefs with an experienced buddy 50' away, but constantly aware of each other. At 95', we may still be 20' or 30' away doing our own thing. Somewhere around 100' I start flying in tight formation with my buddy, and by 120' we will be side by side at arm's length.

I'm also in very close buddy contact during ascent and particularly during safety stop. If you look at incident reports, an amazing number start during th 15' safety stop ---- probably some sort of delayed effects from the earlier portion of the dive.

 

[DA Aquamaster]

Charlie99 once bubbled...
What article was this?

I've been trying to remember where I read it and I'll poke around for it after I get back from diving this weekend.

 

[Al Mialkovsky]

On air I've dove to 232 feet but that was years ago. I did a couple of 200 foot bounce dives on the back wall of molokini recently. I prefer dives in the 100 foot depth so I get a little more down time. Most of my dive are above 50 feet. In Oregon there isn't anything to see deep.

 

[Gr8fldiver]

150-180 in Coz all the time (w/ 120s). Mostly here at home I dive EAN 32/6. Most diving here is 100' or less.

 

[rjdiver]

Back in '95 we had a planned multi-level dive with a 140' max depth. As the DM started back up, I followed him, so I only hit 130'. I had been to 130' before that a few times. No real thrill, looking back, but it was exciting to go that deep at the time.

 

[Gilligan]

As you can see from all the posts on this there is no real answer. Everyone is different. It breaks down to your own comfort and safety levels. I dive only on air as I have no need to spend the extra bucks on Nitrox. I can take a nap after diving as I am retired. I do 1 tank dives from my kayak about three times a week an do a lot of solo diving in the 60 to 80 foot range. I am familiar with the dive sites as well as my personal comfort levels. That doesn't mean something can't happen. But then again if it does that's my responsibility, as it should be. Solo diving opens up a whole new can of worms.