Deep Air - Here we go again....

[DaleC]

The only issue I have with the commercial divers is that they are acting like what they do has anything to do with scuba.

I know what you mean. That's how I feel when people post into OW threads with cave diving solutions.

 

[InTheDrink]

Summary: Reg believes that people don't get better at handling blood alcohol, they just sober up faster. Reg believes that people don't get better at handling nitrogen narcosis. Reg does believe that rote physical tasks can be practiced while drunk.

Thanks for the post and the info on metabolising alcohol.

I appreciate there is no doubt a chemical component to tolerance. However there is also a psychological (if that's the correct word and it probably isn't) component to tolerance.

There is a mental counter-balance to inebriation that comes with practice . So being aware of one's impaired condition can allow the person to take counter measures to compensate. The awareness of the amount of impairment (which only takes place through repetition) can allow the person to moderate motor functions or actions to match the level of impairment. Alcohol may be a bad example in this instance because it also reduces caution, but other types of intoxication don't necessarily and in these instances behaviour can be modified to take into account or mitigate the level of intoxication.

It might seem like I'm labouring the point, but narcosis could well be the same where there is a general mental recognition of impairment and appropriate counter measures taken to manage it. For normal, routine, well practised tasks.

However, I would imagine that if tasks were loaded, or with additional stresses, that the success of the 'tolerance' could be negated pretty quickly. I would agree that if something 'new' had to be done, that the 'tolerance' might not help particularly much and so for this reason I can see why deep air could be construed as having too many risks. I've never been deeper than 40m so I'm not speaking from a position of much experience.

But if some agencies are recommending a He mix after 30m, then I guess 40m falls into this category and I really cannot see any way in which I would ever be looking at anything other than air or nitrox for those depths and somewhat deeper than that, should I ever has reason to (for my kind of leisurely diving).

Summary: John believes tolerance to narcosis is probably like tolerance to any other narcotic on the psychological front and therefore can be trained for to some degree but that He mixes probably make sense on dives deeper than recreational limits or for specific purposes where task loading is likely and clear thinking probably essential. John also has never dived with Trimix but would really like to one day

 

[DCBC]

However, I would imagine that if tasks were loaded, or with additional stresses, that the success of the 'tolerance' could be negated pretty quickly. I would agree that if something 'new' had to be done, that the 'tolerance' might not help particularly much and so for this reason I can see why deep air could be construed as having too many risks.

Actually in testing at DCIEM we found that experienced Navy divers scored substantially better on problem solving skills when compared to 3rd year Medical students. The tests involved time and accuracy testing of motor skills and problem solving skills. Both groups performance dropped from surface scores, but the divers experienced with narcosis had scores that averaged 30% better than the non-divers.

 

[Reg Braithwaite]

Actually in testing at DCIEM we found that experienced Navy divers scored substantially better on problem solving skills when compared to 3rd year Medical students. The tests involved time and accuracy testing of motor skills and problem solving skills. Both groups performance dropped from surface scores, but the divers experienced with narcosis had scores that averaged 30% better than the non-divers.

This isn't what you are saying, but it really reminds me of the SpareAir debates. What I read was people saying, "I'm not going to spend the $$$ on doubles and a pony is too much bother, and I am not going to restrict myself to diving with a trusted buddy, and I refuse to stay close to another diver, and I won't stay shallow enough to comfortably swim to the surface. Therefore, my options are down to SpareAir or nothing, so I choose SpareAir as it's better than nothing."

Now here we are saying that acclimatizing yourself to narcosis makes you 30% better than nothing. Fine. But what we are also saying is, we want to dive deep and we don't want to spend the $$$ on helium.

The arguments seem to have the same structure.

 

[dumpsterDiver]

This isn't what you are saying, but it really reminds me of the SpareAir debates. What I read was people saying, "I'm not going to spend the $$$ on doubles and a pony is too much bother, and I am not going to restrict myself to diving with a trusted buddy, and I refuse to stay close to another diver, and I won't stay shallow enough to comfortably swim to the surface. Therefore, my options are down to SpareAir or nothing, so I choose SpareAir as it's better than nothing."

Now here we are saying that acclimatizing yourself to narcosis makes you 30% better than nothing. Fine. But what we are also saying is, we want to dive deep and we don't want to spend the $$$ on helium.
The arguments seem to have the same structure.

I didn't seem him argue that? His post indicates that there is some evidence that divers can acclimate to narcosis.

With regard to deep air divers: there is probably some selectivity to it. The people that have a low tolerance for narcosis are probably going to avoid it and the people who (for whatever reason) have a higher tolerance are the ones engaging in deep air dives. They are probably going to be the ones who view a 150 ft air dive as unremarkable and the people who feel significantly impaired at 110 feet are going to view the same dive as bordering on suicidal.

 

[ucfdiver]

the people who have a higher tolerance are the ones engaging in deep air dives.

The death list implies that people WITHOUT tolerance are doing it, too...you "forgot" to mention that.

 

[Sloth]

Here is an interesting DCIEM study looking at the nitrogen narcosis adaptation rate of experienced divers.

Rubicon Research Repository: Item 123456789/2199

11 divers where taken to 54 meters and 3 meters and were given a tasks to preform, these tests were preformed over 5 consecutive days. The study had a subjective (how do I feel) component and a performance (reaction) test component.

Divers showed adaptation to the subjective component but only showed learning for the reaction test.

In other words by day three divers felt like they were less narced but only showed minimal improvement to the reaction focused tests.

At best the studies concludes that experienced divers can begin to identify their level of narcosis if they correlate how they feel to how much of a drop off in work capacity they will have due to narcosis. Unfortunately they go on to conclude that since there is an adaptation to how you feel when narced you will lose the ability to gauge sensation to work capacity as you adapt to the feel of nitrogen narcosis. So you feel less narced and may decided that you arent as impaired as you really are.

 

[dumpsterDiver]

The death list implies that people WITHOUT tolerance are doing it, too...you "forgot" to mention that.

I'm not sayng that people that might be less sensitive to narcosis aren't going to get killed.

Also, some of those deaths, were clearly pushing the limits. Just as some agencies set an END of 100, certain people might set their END at 170, 200, 250. I personally feel that there is a huge differeence between 150 and 250 and some of those people are diving way past 250 on air. Obviously there is some depth where the activity approaches recklessness.

 

[LiteHedded]

I'm not sayng that people that might be less sensitive to narcosis aren't going to get killed.

Also, some of those deaths, were clearly pushing the limits. Just as some agencies set an END of 100, certain people might set their END at 170, 200, 250. I personally feel that there is a huge differeence between 150 and 250 and some of those people are diving way past 250 on air. Obviously there is some depth where the activity approaches recklessness.

then why do it?

 

[InTheDrink]

then why do it?

Why do what?

Why engage in any activity that has substantial risk? It only makes sense in that man has a thirst for adventure, exploration and testing himself. And that's man as a whole and man as individual.

Why do the best climbers insist on doing the 8,000m peeks without oxygen?
a) for purist/aesthetic reasons
b) to move lighter and quicker
c) because it sets them apart

Why would a diver dive deep on air? I'm sure I couldn't comment from any position of experience but I can certainly understand the appeal of the challenge.

And who wants sanitising of adventure anyway? I'm not suggesting it be proposed by agencies, but if this is what some people want to do, then why not? Especially when put up against essentials of the argument: My need for adventure the way I skin it is acceptable. Yours is not.

The 'it'll only close places down' argument doesn't really hold water. Plenty of CCR and cave divers NOT ON AIR have met their end engaging in 'their thing' - are they to be held in contempt too?

J