247 Feet -- "We can't stay here for very long"

[lermontov]

You're not alone.

Performance is also a pretty complex topic. Take a diver performing a mechanical assembly. Sensory perception, muscle control/texterity, the ability to concentrate, balance, about a hundred other factors interact. I think it is fair to say that we all perform better with familiar tasks and experience managing distractions. I cringe when Narcosis is compared to alcohol or hallucinogenic narcotics because the analogy is very misleading.

@drbill's slow workup approach is the most prudent approach for individual self-discovery. Unfortunately very few divers get the opportunity to dive often or deep enough to experience the relatively short-lasting acclimatization phenomenon. However, the gradual and repeated baby-steps nearing increased levels of Narcosis does help you manage and, more importantly, detect how and to what extent Narcosis is compromising you. Once detected and it exceeds your comfort level the cure is pretty simple... go up.

it would be interesting to try and quantify what percentage is related to psychological factors. Diving at 60m and 27º with 30m vis in the tropics in shorts and t shirt is a world apart from 37m in 12º in 2m vis with dry suit etc
i've noticed different levels of narcosis for different situations so its a hard to draw a line in the sand -as you said recognising the point when the narcosis is compromising you beyond your comfort zone is important

 

[Compressor]

it would be interesting to try and quantify what percentage is related to psychological factors. Diving at 60m and 27º with 30m vis in the tropics in shorts and t shirt is a world apart from 37m in 12º in 2m vis with dry suit etc
i've noticed different levels of narcosis for different situations so its a hard to draw a line in the sand -as you said recognising the point when the narcosis is compromising you beyond your comfort zone is important

It would be VERY insteresting as the work loads are different and thus the carbon dioxide production also vary. Increased carbon dioxide production leads increase cerebral blood flow and increase delivery of N2 to the brain. Maybe this study has been done by physiologists; I just don't know.

 

[Bob DBF]

Interesting stuff! I wonder, in the 1950's, how prevalent and reliable were the types of info. we recognized as 'diving tables,' and later dive computers? Did these guys know and choose to disregard NDLs, in other words?

The US Navy tables worked fine for me from '62 to '06 when I bought a computer. A lot of my dives had a bottom that would be difficult to break NDL with the two tanks I had. As for disregarding NDL, I never did, but that doesn't mean that I stayed within NDL. At the time there was no "tech diving" specialty, just the progression into advanced dives which could include decompression diving. This was using mentors and the Navy dive tables which included decompression diving. I was one of the lucky ones, the tables worked for me, I stayed within them and I never got bent.

To determine 'nuts,' we need to consider what they were trying to do, was it reasonable, under what circumstances (e.g.: knowledge base to draw from, equipment options) and if all that was legit, were they conducting themselves in a reasonably safe manner given the resources they had?

Nuts is a moving target, I did the best with the gear and information I had at the time. In hindsight it is easy to paint the picture of a bunch of crazy cowboys doing stupid sh*t, but everyone I dove with was trying to make it back home safe and sound.

I'm with @drbill with a work up when doing dives where narcoses comes into play. May be it was the times in which we learned, but it seems to work. I would say that it makes you more aware of your level of narcosis and ability to function through it, rather than make you immune. The workup also reminds me of the point a which I have to leave rather than get more impaired, a handy piece of information.

I was told by one of my mentors, the real problem with narcosis is not knowing you are narked, then finding out during an emergency that you are. That surprise may last long enough to kill you.


Bob

 

[Akimbo]

was told by one of my mentors, the real problem with narcosis is not knowing you are narked, then finding out during an emergency that you are. That surprise may last long enough to kill you.

I concur and well stated. I may have to plagiarize that.

 

[The Chairman]

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A ScubaBoard Staff Message...

Off topic and argumentative comments have been removed from this thread.
This is the history of diving forum... please keep physiological discussions to the appropriate forum. Thanks.

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[Compressor]

Thank you.

 

[MrVegas]

I hesitate to bring this thread back to life, but I just watched another one of the Cousteau documentaries where they were diving the blue holes in Belize and the Bahamas. From a historical perspective, it was interesting to see the procedures. They did a 165 ft deep cave dive on air -- Cousteau frequently bringing up dealing with narcosis in the narration, mentioning that they had an hour of decompression after the dive, and the comment that they had pushed to the reasonable limits of risk. Fascinating to watch. There were no staged tanks in view and they all just appeared to be diving a set of big doubles.

At any rate, as a new diver, I honestly had no idea when I started this thread how contentious the deep air discussions were -- now I know, so I feel a little bad for setting all of that off. I just thought it was interesting from a historical perspective. Different times and different plans I guess necessitated by the technology available. I also wanted to say that this history section on the forum has been great reading generally. Thanks to all of those who posted stories and histories. Great stuff.

 

[mcohen1021]

I hesitate to bring this thread back to life, but I just watched another one of the Cousteau documentaries where they were diving the blue holes in Belize and the Bahamas.

JC is the reason I learned to scuba almost 30 yrs ago - do you have a link to that video? I would love to see it.

 

[kelemvor]

My family and I got certified this summer, and have had fun diving local quarries -- I am now taking a look back at some of the old Cousteau shows I used to watch when I was a little kid (1970s). I was watching the Silent World last night (1956 or so? -- before my time). At one point, the divers with just compressed air tanks strapped to their backs go down to 247 feet -- Cousteau says "we can't stay here for very long." Earlier in the movie, they are at 165 feet looking for lobsters, and one apparently gets narcosis and the bends -- although it looks a little simulated for the film. (It helps to have a recompression chamber on the boat, I guess.) No computers, no BCDs, no pressure gauges, etc. They seemed to accept nitrogen narcosis as a regular part of diving.

This looks crazy to me -- was the science just not fully developed yet, or were they nuts? (Not very politically correct either -- they blew up a coral reef too and everyone seems to have a cigarette in their mouth.) A fascinating film, though, and I still remember Cousteau's unique voice from when I was a child.

Cousteau did things both great and terrible, no doubt about it. I've decided I'm not a fan, although I'd stop short of wishing he hadn't happened to the world. After all, he inspired so many to dive that I might never have learned about the sport otherwise.

 

[Akimbo]

Cousteau did things both great and terrible, no doubt about it. I've decided I'm not a fan, although I'd stop short of wishing he hadn't happened to the world. After all, he inspired so many to dive that I might never have learned about the sport otherwise.

He was also responsible for raising environmental awareness about the oceans more than any other individual I can think of. Nobody's perfect... or 100% consistent. I'm not a fanboy for Cousteau but he accomplished a lot.