Deep Air

[LiteHedded]

I think you have to put this in perspective. Narcosis is but one problem a diver may have to overcome. There are many, take current for example. If you had slowly built-up your current experience so that you had a few hundred current dives under your belt, I'd suspect that you would be more comfortable, even more competent to dive in conditions where another diver would be deemed to be unsafe.

Narcosis is a problem for everyone, however the depth at which it affects the reasonable safety of a diver will vary. Divers may slowly build their experience to recognize and deal with a degree of narcosis. By doing so they develop their ability to better prepared to dive deeper on air than another diver who has not has this experience.

I'm not promoting unsafe diving practices. I am saying that the most dangerous time for any diver is when they are developing their basic skill-sets. Dealing with some degree of narcosis use to be a basic skill.

I agree that a diver is best to never experience narcosis. This can be done by using the right gas for the target depth. If this gas(s) are not available however, the diver has to make an informed choice regarding safety. The only way I have increased my ability to dive deeper on air has been through experience. If the diver never gets the experience, s/he is the same as the diver who has never had to deal with current, cold water, waves, etc.

These are all hazards. In-truth, we should never enter the water if we want to be truly safe; but as we all know, we can develop skills that allow us to venture forth.

So back to your question. As I have extensive trimix and heliox experience and in no way am I trying to be macho, I have to disagree with your statement.

I would agree with that.
and I wasn't referring to you obviously
bottom line is everyone is free to make their own decisions. we're adults. I think everyone knows where I stand at this point

 

[Thalassamania]

What is a wonky mix

The guys at EN were usuing Trimix... ( last report I read anyway )

Last, do you not realize that narcosis affects people differently? I wont even consider trimix unless im gonna start diving below 200. As a diver i would hope you look at each stage of the dive and be able to be honest with yourself as to if you should proceed. Air / trimix.. If you want to over pay for your dive go ahead, if you narc easily I dont blame you. Notning wrong with air if you can handle it.

It effects the same person differently on different dives too.

wonky's a fun word to use.

and an END approaching 180' and ppo2 approaching 1.7 is 'wonky' to me.

Just call me Willey, when I was training with Pyle we were diving air to 170 because that was the END of the planned mix dives.

 

[Kevin Carlisle]

It effects the same person differently on different dives too.


Just call me Willey, when I was training with Pyle we were diving air to 170 because that was the END of the planned mix dives.

Willey wonkey??

 

[Doc Harry]

I had hoped we were going to talk about extreme responses to physiological stresses. Where did I expect it go? Well, actually, thinking about it I suppose you are right - it was just too much to ask.

Okay, sounds like a great topic. Your OP did not make that clear. In fact, your orignal post appears to be just another argument in favor of deep air diving.

Did you want to talk only about "extreme responses to physiological stresses" in regards to deep air only? Or did you want to talk about all kinds of extreme responses to all kinds physiological stresses? How about psychological reponses?

If your questions were a little clearer, then we could respond with a bit more focus, too.

 

[Trace Malinowski]

Trace, You have a lot of experience and are well traveled. If trimix/heliox is not available, what limits do you personally place on air? Is there a line you will not cross? How do you deal with this issue?

That's a really good question. Because the answer is complicated by external factors.

For me personally, I think 150 feet is a fairly good cap for deep air and advanced nitrox diving, mostly due to my decompression obligation. I can still get 20 or 30 minutes of bottom time and have an ascent profile similar to what I would run on trimix. If all deco gases were lost, I could still get up and out of the dive on my preferred equipment of twin AL80's. As hang times become longer for lost gas with bottom times of 20 to 30 minutes, venturing deeper would be asking for trouble with my volume limitations.

I prefer AL80's because I have become very used to them and lugging them around isn't as bad as steel tanks, so my wreck diving is usually limited by the constraints of my available gas volume. My back also likes AL80's better than steel tanks at my age.

Also age-related, I tend to become cold more quickly than I used to and dive times in northeast waters of about an hour and change are enjoyable. After years of freediving, I wonder if my body developed some sort of Pavlovian response to anything cool? Either the mammalian diving reflex is being triggered the moment a breeze or some water touches my temples, or I'm just old now!

I have found myself needlessly concerned about math and directional information when diving air to depths to 150 feet as well. At 130 feet on the U-853, I started second guessing my directional decision and wondered if I was swimming the wrong way to the anchor line after a penetration. That caused a couple minutes of concern since I had become stuck inside and ended up shearing off my left post handwheel extracating myself. The additional time inside put me close to my planned max consumption and I wanted to get off the wreck on time without any other glitches. Things like that and other minor memories like a computer misread at 140 haven't happened since using trimix. Navigation is a forte with me, so I know soimething is up when I'm not sure which way is home.

During my apprentice cave course, my instructor wanted me diving air and we kept me task-loaded at 130. I feel confident about being at 130 on air in caves from being tried by fire, but I also wonder if some of the mistakes I made during shark attacks at depth would have been made in shallow water or with mix? 130 is definitely my cap for cave diving just because the environment is less forgiving.

Depending upon the circumstances, I would push these self-imposed caps deeper. For example, if we had access to a cave in the islands or Mexico with only air and no way of getting trimix, I may extend my 130 air cap. But, to do that, I would be building experience in the cave as depths increased with subsequent dives. I wouldn't move right to a 140 foot dive in an unknown system.

If you wanted me to do a deep wall dive in warm-clear water in the tropics, like Bonaire, and we had surface support in case we had any gas issues, I could extend that pretty deep. Such wall dives often have very simple dive plans, no complex navigation, and I can deco longer in thermal comfort.

Gary Taylor wants me to take the narcosis management program offered by PSAI for my own growth as a PSAI instructor. So, I may or may not be venturing deep again on air to experience the program.

I guess the simple answer would be that it would depend upon what equipment and regulators I was using, how much air and deco gas is available, how much surface support, the thermal issues, the availability or cost of the helium, and the complexity of the task at hand.

I have a certain flexible morality.

 

[Doc Harry]

TraceMalin,

A lot of good information there, thanks. I agree with your statements about limiting depth in caves, it's good to see other people say what I've been thinking in my head.

I've been to 140 fsw on air on the Caribbean wall dives on clear sunny days and didn't really appreciate any subjective sensation of narcosis. I've been to 120-130 feet on numerous other wall dives in similar conditions and only rarely developed a subjective sense of narcosis.

However, this summer I went cave diving to 150 feet in Eagle's Nest (I think I was on EAN24, but I don't have my log book here). Holy smokes, I was so narc'd I couldn't believe it. I was trying math in my head and couldn't even do simple subtraction without intense thought. Perhaps it was the darkness or a combination of darkness and rapid descent. Certainly task loading plays a role, too, but even when we were just lazily cruising around the cave I remained really narc'd until I was ascending up through the tubes.

I know that deep air diving has been around for a long time, but I have stopped going deep on air/Nitrox until I can get Trimix certified. I just can't imagine how I would have managed in Eagle's Nest had something gone wrong with that degree of narcosis.

 

[Thalassamania]

You manage wherever you are, however narked you happen to get, because what's the alternative to not managing?

Most of the time it is easier than other times, sometimes it's a little annoying, rarely its really hard, and/or frightening, but you manage ... you have to.

Maybe you finish the dive, maybe you thumb it, it all depends.

 

[Peter Guy]

Maybe you finish the dive

Well, yes, one way or another you will finish the dive.

 

[PfcAJ]

Well the problem with that is at this level of diving that you and I do we should be evaluating the dive every step of the way.. If I am with you and I feel weird I m going to say hey time to go. I am not gonna take a chance on killing me or you.. I check my senses often to make sure I am thinking rational.

I just dont see trimix as the miracle gas as others do. I know at 153ft I am very clear headed....snip

So at 150ft, (under some amount of narcosis), you think you're clear headed. How can an intoxicated individual accurately assess how impaired they are...while they are impaired? The very act of checking yourself is subject to the negative affects of narcosis!

All of this boils down to one thing, and that's saving a buck. You said it yourself. This is like not changing brakes or tires...just cuz its cheaper...

 

[nadwidny]

You manage wherever you are, however narked you happen to get, because what's the alternative to not managing?

Not doing the dive in the first place.