Why dive Deep Air?

[jpbutler]

What do you understand the "Wawas" to be ?

I think that it is auditory hallucinations from being narc'd like the sound of my breathing thru the regulator being distorted.

 

[ianr33]

My understanding is the Wawas is something that happens at crazily high pO2's rather than anything to do with nitrogen.
Not something I ever wish to experience
Wah Wah.final

 

[PfcAJ]

I had a period of a few years in my life when I was a drunk. When you drink every day, you often learn to do things well enough even in a drunken state. I remember one night being given a ride home by someone who was trying to help me out. Unfortunately, she was probably the worst driver in the state of Washington. Halfway through the drive I asked her to pull over and let me drive. Even three sheets to the wind, I was a better and a safer driver than she was. That's not an exaggeration either. She was downright scary behind the wheel.

That doesn't mean it was a good idea or very responsible for me to drive drunk though, only that some people can still function reasonably well even when they are seriously impaired.

Narcosis seems to be the same way. I begin to notice it at about 100'. Come 130' it's really kicking in, especially if I have been doing any finning. Now, I'm sure that with enough experience that many people can learn to function in spite of it, and I'm sure that there are plenty of people out there who are better divers on air at 200' than I am on nitrox at 60'. I'd guarantee you that they are better divers at 60' than they are at 200' however.

For me it's just not worth the risk. Diving's risky enough without feeling plastered at 160'. I wouldn't criticize an experienced deep diver who feels otherwise though.

A persons subjective assessment of how they feel is a horrible measure. People on anesthetics usually feel pretty good...

Yes, drunk folks can function to an acceptable level on familiar tasks. The catch is when they are presented with something unfamiliar. Same goes with diving. If you practice something over and over again, eventually you'll get it right. But what happens when there is an issue? Now you're slipping down the incident pit.

From which I assume you are implying that drunk drivers kill people, which is true, but you overlook the large majority of fatal accidents (80%) in which the driver is not drinking. Obviously they were impaired as well but there is no convenient label with which to demonise them.

The real question is how much control should one man have over another. Personally I do not believe in slavery. (See how one word can taint the actual discussion.)

'92 was the last year and you listed 8 fatalities, during the period '92 to '03 there were on average 86 scuba fatalities per year, 93% were not on deep air. With this in mind I would try to reduce the majority of fatalities rather than focus on "amazing divers"(your quote) that have decided to take a different path than you.

I do not dive Deep Air but when I am deep and feel the onset of narcosis I either finish my plan or head up depending how it hits me, but I get slightly paranoid and very carefully and I thank god the SPG came into recreational diving. My point is that everyone should be able to plan and execute their own dives.

To quote DCBC "What is and what is not an acceptable risk for a person is not for you or I to decide." The fact that there 119 fatalities each day on the highways puts in perspective the risk management you need before you even get to the dive site.

Bob
-----------------------------------
I may be old but I'm not dead yet

Of course there are more sober deaths. There are more sober drivers... However, there are far LESS drunk drivers on the road, and a higher percentage of them end up in accidents.

My issue is with deep air "training". Imagine if there was a class by an organization on driving while drunk or high... Thats ludicrous.

So you are saying that all the dive agencies (except GUE/ UTD ) are behaving in a criminal manner by taking divers to over 100 feet on air ???

This may come as a shock to some but IMHO 120 feet on air in warm blue water is not exactly a Big Deal

I do. Saying that the limit is 130' on air is real bad. How many "advanced" divers are out there with zero knowledge of gas management, poor buoyancy, and no dive planning skills? We've all seen them. People keep getting hurt, and they will continue to get hurt.

And no, it isn't a big deal to dive to 120. Squirt a bit of helium in there and go. At least you'll remember it.

Diving in perfect conditions (Cayman/Bonaire) I'm fine with doing 160 on air. I'm not as sharp mentally as I would be on Trimix but thats acceptable to me. Its easy to ascend at any time and a Trimix fill in those locations is around $100

This is like driving home drunk because no taxi is available. Maybe the answer is to not drink in the first place?

 

[knotical]

I've got maybe 30 dives from last year below 120 on Nitrox going as deep as 160.

I don't understand why you're going deep on Nitrox. It seems you're increasing your risk of OxTox for the uncertain benefit of reduced narcosis. Uncertain because oxygen is also reported to be narcotic.

 

[Trace Malinowski]

We all know 130 ft. is the rec. limit, one which I never (intentionally) intend to go below. But other than to say "hey, guess how deep I went", are there any other reasons to do this? Got to figure that the incredibly short NDLs down there plus all the ongassing on the way down (AND up to a point) makes it awfully risky. As well, what can you do down there with about 4 minutes bottom time? I'd like to hear from those who have done this for reasons OTHER than bragging, or just to see if they could do it.

The 130 foot recreational limit was put in place without considering what we know today about decompression modeling, mixed gas use at recreational depths, and current equipment technology.

For some, 130 feet is "too deep" on air. For others, 130 feet is "just right" as a cut-off for air use. For others, 130 feet is too "soft" or conservative.

Lastly, for some rugged individualists who are explorers, they will make due with whatever tools they have at their disposal, employ them as safely as they can under the circumstances, and go diving with total knowledge of the risk vs. reward of air diving at any given depth be it "shallow" or "deep".

 

[adm3745]

I don't understand why you're going deep on Nitrox. It seems you're increasing your risk of OxTox for the uncertain benefit of reduced narcosis. Uncertain because oxygen is also reported to be narcotic.

I usually run PPO2 of 1.2 past 100 ft. It is uncertain but it could be help. I don't feel at risk at 1.2 from ox tox. Even if the EAD is only 10 ft less, it's still a little less inert gas absorbtion. I don't pay any more for custom mixes so I might as well run 25 or 26 at 130 ft. I'll start running 21/35 whenever I Get the trimix card so I can start to remember profiles.

 

[shoredivr]

gotta love this avatar though of post #3. It's the only thing original in this thread

Sorry, Mike, but Reg Braithwaite had that hilarious avatar a while ago...so not even that is original

 

[captain]

The 130 foot recreational limit was put in place without considering what we know today about decompression modeling, mixed gas use at recreational depths, and current equipment technology.

For some, 130 feet is "too deep" on air. For others, 130 feet is "just right" as a cut-off for air use. For others, 130 feet is too "soft" or conservative.

Lastly, for some rugged individualists who are explorers, they will make due with whatever tools they have at their disposal, employ them as safely as they can under the circumstances, and go diving with total knowledge of the risk vs. reward of air diving at any given depth be it "shallow" or "deep".

The 130' limit was put in place by the US Navy because that was the limit time and depth wise that allowed a reasonable amount of work to be done on scuba with twin 90 cu/ft tanks.
It had absolutely nothing to do with narcosis as scuba was allowed to 200 feet for short duration jobs and surface supplied air for long duration jobs and still is.
In the beginning rec agencies simply adopted what the Navy did without questioning why the Navy did what it did even though most rec diving was done with single 72 cu/ft tanks. Since then rec agencies have thrown in various depth limits for various reasons unrelated to narcosis in most cases..

 

[Rhone Man]

I read in a non-authoritative source that the CNS depression from heavy (200ft+) nitrogen narcosis was known to protect against the O2 toxicity. Does anyone have a reputable source (either way) on that?

I wouldn't bet my nickels on that one. The same folks that say that are the same folks that think deep air is ok.

I was a bit surprised more people didn't pick up on this... this does strike me as something I haven't seen discussed much before (on SB or elsewhere). I have heard a lot of anecdotal evidence that on equal partial pressures of oxygen, you are less likely to tox on a leaner mix at greater depth than you are on a richer mix at shallower depth, but no one really knows why.

All those years that people were diving the Andrea Doria on air going as deep as 250 feet, plenty of them died, but (with the possible exception of Richard Roost, stressing the word "possible") nobody seemed to suffer oxygen toxicity despite diving with a ppO2 north of 1.6

I think I recall John Chatterton posting on SB (or it might have been something he said in a seminar) that for some reason people didn't seem to tox as much on deep air as mathematically they ought to have.

And I got a good roasting on SB a little while back for posting a thread asking for thoughts on (amongst other things) why during Bret Gilliam's dive to 475 feet on air, which would have given him a ppO2 somewhere around 3.2 ATA, he didn't tox.

 

[ianr33]

I do. Saying that the limit is 130' on air is real bad. How many "advanced" divers are out there with zero knowledge of gas management, poor buoyancy, and no dive planning skills? We've all seen them. People keep getting hurt, and they will continue to get hurt.

Lets leave aside the divers with poor skills and no gas planning. I totally agree with with you on that.

What I am talking about are well trained,capable divers with redundant gear,good gas plans, understanding of deco etc etc.
In a non overhead environment,80 degree water ,100 foot viz,doubles and deco tank diving to 130 is totally reasonable to me. I guess we will have to agree to disagree on this and thats fine

How many divers would turn down a free trip to Truk beacuse they would need a mortgage to import the He?

I've never understood the blanket END<100 rule/suggestion. Diving Bonaire is not the same as penetrating the Empress of Ireland