Deep Air Diving - thoughts

[Thalassamania]

Hm ... for me to take someone to 200 feet on air.

Written document describing why the diver needs to make the dive.
Diving Duty Physical Exam.
100 hours entry level training (rough equivalent NAUI Master Diver).
Minimum 75 logged dives.
Minimum 720 minutes between 0 and 30.
Minimum 720 minutes between 30 and 60.
Minimum 360 minutes between 60 and 90.
Minimum 240 minutes between 90 and 130.
Minimum 120 minutes between 130 and 150.

One more dive each, with me, to 60, 100, 130, and 150 feet.

Then I'd consider it. No charge. Cheaper than a chamber ride.

 

[Geoff_H]

You can decide your level of risk but I take issue with advocating that level of risk to others in the light of scientific evidence clearly demonstrating the impairment present when deep air diving.

What do you think of the information DA Aquamaster posted, talking about a study showing the impairment through narcosis varied with the expected effect?

Could that explain the difference in effect that you perceive and the experiences of some very experienced divers on this poor who have made hundreds of deep air dives who have posted here?

 

[Thalassamania]

All deep dives are impaired dives to some degree, its a question of the degree and how much today.

 

[wedivebc]

What do you think of the information DA Aquamaster posted, talking about a study showing the impairment through narcosis varied with the expected effect?

Could that explain the difference in effect that you perceive and the experiences of some very experienced divers on this poor who have made hundreds of deep air dives who have posted here?

I believe you are referring to this experiment:

Author Bret Gilliam7 described a 1965 study conducted by Tom Mount, a pioneer in U.S. cave diving, and Dr. Gilbert Milner. They studied the effects of “anticipated behavior modeling” with respect to perceived and observed (subjective vs. objective) effects and the probability of experiencing nitrogen narcosis.
In this experiment, three groups of divers received information regarding the topic of nitrogen narcosis:

• Group 1 was told that there was a high probability of experiencing the effects of nitrogen narcosis — in fact, they were told that everyone experienced severe symptoms at 130 feet / 40 meters.
• Individuals in Group 2 were informed that there was such a state as nitrogen narcosis, but that this was relatively rare and only a few people experienced symptoms at depth.
• The final group received a lecture regarding the recognition of symptoms, risks and dangers, but were told that persons with a strong will were able to resist and / or overcome symptoms of narcosis.

In test dives between 130 and 240 feet (40 and 73 meters), the group who expected to experience symptoms of narcosis actually experienced these symptoms with greater frequency and severity than did persons in the other groups. Dr. Maxie Maultsby, a proponent of rational behavioral therapy, discussed what he termed “negative self-talk,” our habit of continuing in a pattern of maladaptive responses — in this case, our continuing to tell ourselves that we can’t handle a situation. However, Maultsby maintains that, if we can talk ourselves into a pattern, we can also talk ourselves back out.8

 

[Bismark]

What do you think of the information DA Aquamaster posted, talking about a study showing the impairment through narcosis varied with the expected effect?

This is most interesting and a double blind study should prove useful. I remember one time substituting non-alcohol beer to a friend at a university party and after several of these (okay, so more than several), his actions became one of the most remembered events of the year. He acted as if he had been drinking regular beer and we actually had to show him the cans..... Not very scientific but pretty funny.

Could that explain the difference in effect that you perceive and the experiences of some very experienced divers on this poor who have made hundreds of deep air dives who have posted here?

I think we really need to distinguish between perceived effect and physiological impairment that is a function of physics and biology. I have no doubt that different people perceive different effects and that these change from day to day and are as variable as the wind. One day two martinis have a completely different effect on me then they might have on another day. However, the simple fact is that you are impaired and this is a physiological fact. Arguing about someone's ability to "tolerate" narcosis is akin to arguing about someone's ability to tolerate alcohol. What is the point? This isn't a question about who is stronger, tougher, more able to focus or whatever. We are talking about a physiological reaction to increased partial pressure of gases. Period. This is science. Narcosis is impairment. Period.

I am also aware that if you have to accomplish a task at depth on air, that you can work up certain exercises to make it more likely that you will accomplish that task. However, I don't think we should confuse this with "tolerance" to narcosis. You are and will always be impaired. The level of that impairment will vary from day to day and from dive to dive, but it is always there. The very definition of impairment presupposes an inability to respond quickly and effectively with little likely hood of error to an emergency. That to me is an unacceptable risk in what is a recreational sport. More importantly, my biggest concern is that divers without the experience or knowledge are "experimenting" based on the individual experiences of some, rather than approaching this with a solid understanding of the risks. Moreover, each time someone states that they "routinely dive to 200' on air" they are telling new divers that this is okay and not a big deal. Many of the readers of this forum are new divers and easily impressionable. No matter what anyone else says, I don't believe we have gotten past the "how deep have you gone?" questions. As an instructor, I am sure I hear that question by at least one student each class. These students are exactly the type of divers who will try a 200' dive without the proper experience or equipment or training based on that same person who posted that they "routinely dive to 200' on air".

Earlier in this thread, someone asked me "what business is it of mine" to tell someone what they can and can not do. My answer to this is of course it is not my business. However, I feel a moral obligation to present both sides of the equation to someone who wants to know. From a teaching point of view, not doing this is, in my opinion, a grave injustice to our student. Ultimately, I think we need to remove the rhetoric around deep air diving and trimix diving and honestly admit to one another that the physics and biology are what they are. No one can argue that narcosis is not impairment. You might as well argue about gravity. The entire argument seems to come down to a question of someone telling someone else what they can and can not do. This is the wrong argument and misses the point. I don't have the right to tell someone else what to do when it comes down to deep air diving (save for my belief that I have one voice in respect to our public health care system in Canada and since I served my country I feel I am entitled to express that view)but I have a problem with the way the argument is presented to new divers.

Different people will perceive narcosis differently; depending on numerous variables; some will experience noticeable impairment while others may not; this varies from day to day and from dive to dive; however the common denominator is that they are impaired and less likely to react correctly and in a timely fashion to an emergency. My belief is that this needs to be stressed to beginning divers rather than providing anecdotal examples about how many times they have "dived to 200' on air". I remember reading about a diver (who shall remain nameless....) who had "trained himself to squeeze his power inflator" just as he felt himself becoming unconscious. I remember thinking that this guy had to have been joking but apparently he was not.

I wasn't really that long ago when divers looked at Nitrox as the devils gas. Now you would be hard pressed to find a diver who didn't at least know what it was and I understand that it is the most popular diver training specialty. I don't think it is a stretch to compare the growth of trimix diving with the growth of nitrox. There will always be those who still claim nitrox offers no useful advantages for the higher cost. Of course trimix is considerably more expensive than nitrox, but the growth curve will probably be the same shape, just smaller. Just my guess and time will tell but trimix diving has grown in leaps and bounds in the last 10 years and "tech lite" is one of the most popular new growth areas in diving. Let's wait and see if I am right or not.

(And I said I wasn't going to write anything else here...........)

 

[Bismark]

Oops, I don't really know how to break up someone's quote and answer questions separately. In the case above, my comments on the first question appear in the middle of someone else's quote. Sorry, I don't know how to fix it!!

 

[John_B]

So instead of measuring perceived vs. actual impairment, they tested only perceived impairment so the results would fit their hypothesis. Nice...

I believe you are referring to this experiment:

Author Bret Gilliam7 described a 1965 study conducted by Tom Mount, a pioneer in U.S. cave diving, and Dr. Gilbert Milner. They studied the effects of “anticipated behavior modeling” with respect to perceived and observed (subjective vs. objective) effects and the probability of experiencing nitrogen narcosis.
In this experiment, three groups of divers received information regarding the topic of nitrogen narcosis:

* Group 1 was told that there was a high probability of experiencing the effects of nitrogen narcosis — in fact, they were told that everyone experienced severe symptoms at 130 feet / 40 meters.
* Individuals in Group 2 were informed that there was such a state as nitrogen narcosis, but that this was relatively rare and only a few people experienced symptoms at depth.
* The final group received a lecture regarding the recognition of symptoms, risks and dangers, but were told that persons with a strong will were able to resist and / or overcome symptoms of narcosis.

In test dives between 130 and 240 feet (40 and 73 meters), the group who expected to experience symptoms of narcosis actually experienced these symptoms with greater frequency and severity than did persons in the other groups. Dr. Maxie Maultsby, a proponent of rational behavioral therapy, discussed what he termed “negative self-talk,” our habit of continuing in a pattern of maladaptive responses — in this case, our continuing to tell ourselves that we can’t handle a situation. However, Maultsby maintains that, if we can talk ourselves into a pattern, we can also talk ourselves back out.8

 

[Robert Thompson]

It seems that most deep air diving is due to the cost of He. I can certainly say I've been guilty of it. I used to do a lot of deep air dives beyond 200'. Problem is that anytime you have to actually exert yourself your level of impairment multiplies significantly. After the dive you feel awful, and you don't remember much. "why did I go diving, because I don't remember what I saw" The other thing is that in some cases people have severe issues like blackouts, falling asleep (no buddy and you die). I've had people become completely unmanageable at depths as shallow as 130'. So I really don't think air is the right tool for the job.
I can teach extended range to 180', but I would rather get my students on mix.
If you are looking to go into tech, and your interested in diving to 300'+. Start looking at rebreathers. They will pay for themselves pretty quick when your looking at a $150.00 gas bill per dive.
For those of you in San Diego, you will want to check out SDUA Home Page. They have an unlimited gas membership program that will save you a lot of money if you are an active tech diver. SDUA Home Page

 

[Geoff_H]

I think we really need to distinguish between perceived effect and physiological impairment that is a function of physics and biology.

That study doesnt appear to just talk about perceived effects, it talks about objective judgement. I would be interested in reading a copy of the full paper if anyone has it, or a link to to it?

We are talking about a physiological reaction to increased partial pressure of gases. Period. This is science. Narcosis is impairment. Period.

I don't think anyone disputes this, just the level of it. There are plenty of ways to be impaired diving - a little tired, a little headache, a little seasick, a little hungover, a little muscle soreness, a little unfamiliar with your buddy....

Each indivdual will have his own tolerance to how much risk he or she is willing to accept diving, and I think any reasonable discussion of narcosis needs to include that. Some people say they will not drink any alcholol 24 hours before driving.. others will have a single beer with a meal and drive home... others may have a bottle of wine in an evening and drive to work the next morning.

There is little doubt each of these is impaired slightly, but I don't think we can just shout IMPAIRED and close the discussion.

 

[Bismark]

It seems that most deep air diving is due to the cost of He. I can certainly say I've been guilty of it. I used to do a lot of deep air dives beyond 200'. Problem is that anytime you have to actually exert yourself your level of impairment multiplies significantly. After the dive you feel awful, and you don't remember much. "why did I go diving, because I don't remember what I saw" The other thing is that in some cases people have severe issues like blackouts, falling asleep (no buddy and you die). I've had people become completely unmanageable at depths as shallow as 130'. So I really don't think air is the right tool for the job.
I can teach extended range to 180', but I would rather get my students on mix.
If you are looking to go into tech, and your interested in diving to 300'+. Start looking at rebreathers. They will pay for themselves pretty quick when your looking at a $150.00 gas bill per dive.
For those of you in San Diego, you will want to check out SDUA Home Page. They have an unlimited gas membership program that will save you a lot of money if you are an active tech diver. SDUA Home Page

It very well could be the case that that is where we will all end up eventually. I don't know enough about rebreathers to offer reasoned arguments for or against but even though all my training and diving has been on OC, I am a strong believer in using the "right tool for the job". I guess I still have bad dreams about a car I had that wouldn't start if you even mentioned the word rain........I can't get past the electronics and water thing. Guess I am just as guilty as those who used to say nitrox wasn't needed and those who still say trimix is not needed... Sure would have a lot of extra money in my bank account though............