Deep Air - Here we go again....

[rjack321]

It's 2010. We have a whole year of Deep Air threads to look forward to.

Well of course!! There have been a whole new crop of divers trained in responsible helium use that need to see the error of their ways. So they may go forth on deep air and work up to being burly men.

 

[Blackwood]

Oh, I love the black suited DIR/Tech Diver statements that "If you don't dive on Tri Mix your stupid".

And you wonder why you all get such a bad rap from the rest of the scuba community.

Meh. I don't generally identify myself as "DIR/Tech Diver," but if I have a "bad rap" due to the inability of someone else to read and comprehend posts instead of just picking certain parts, removing the qualifying statements, and applying them indiscriminately, I could not care less.



BTW, my stupid what?

 

[Rainer]

BTW, my stupid what?

Given his poor reading comprehension, is picking on his poor grammar really fair?

 

[lobstah]

2. Each individual possesses a different depth envelope to safely dive air.

3. Divers can be trained to expand upon this safety envelope with training. Deep air courses are designed for this reason.

How about you read Bennett&Elliot Physiology of Diving and find an article where they researched the adaptation to narcosis?

For lazy people, here's a summary: adaptation does exists, is short term (read: after you don't get regularly narced for a week you back to square 1) and is most noticeable for simple tasks like hammering a nail. High complexity tasks show little to no improvement with practice.
Level of narcosis also varies for individual on a different days.

And you should probably top it of with another research quoted in Bennett&Elliot which ties gas density to work of breathing and lung ventilation, with WOB observed to be increasing exponentially in relation to depth when diving air below 100-130 feet, while efficiency of lung ventilation drops at the same time, promoting CO2 retention.

So for a price of airfill we get increased N2/O2 narcosis, increased CO2 narcosis (200 times more narcotic than N2) and increased likelihood of O2 tox (which is well proven to be precipitated by increased levels of CO2).

This is based on solid research not some anecdotal evidence "I dove to 190 yesterday and I'm fine" or "Commercial divers do it all the time". NASA was flying space shuttles for 20 years before they discovered they have issues with protective foam destroying thermal protection. Unlike some macho divers - they actually drew conclusions from incidents and changed their ways rather than "Uh... but we did it for 20 years".

But maybe I'm wrong and you actually do have something more than anecdotes to back your claims up. I would love to see them and correct my viewpoint.

 

[Sloth]

How about you read Bennett&Elliot Physiology of Diving and find an article where they researched the adaptation to narcosis?

For lazy people, here's a summary: adaptation does exists, is short term (read: after you don't get regularly narced for a week you back to square 1) and is most noticeable for simple tasks like hammering a nail. High complexity tasks show little to no improvement with practice.
Level of narcosis also varies for individual on a different days.

And you should probably top it of with another research quoted in Bennett&Elliot which ties gas density to work of breathing and lung ventilation, with WOB observed to be increasing exponentially in relation to depth when diving air below 100-130 feet, while efficiency of lung ventilation drops at the same time, promoting CO2 retention.

So for a price of airfill we get increased N2/O2 narcosis, increased CO2 narcosis (200 times more narcotic than N2) and increased likelihood of O2 tox (which is well proven to be precipitated by increased levels of CO2).

This is based on solid research not some anecdotal evidence "I dove to 190 yesterday and I'm fine" or "Commercial divers do it all the time". NASA was flying space shuttles for 20 years before they discovered they have issues with protective foam destroying thermal protection. Unlike some macho divers - they actually drew conclusions from incidents and changed their ways rather than "Uh... but we did it for 20 years".

But maybe I'm wrong and you actually do have something more than anecdotes to back your claims up. I would love to see them and correct my viewpoint.

Ahh man you beat me to it! I was about to post on this study.

To summarize some more there research and others past research demonstrates that divers exhibit some level of narcosis on air from 100ft and on. 200ft appears to be the limit for personal tolerance and 250ft places divers in a narcotic effect that is a threat to their safety.

Bottom line a lot of data points to nitrogen narcosis not being something that can be controlled. Some like the OP may have an inherit nitrogen narcosis tolerance but by no means should anyone base their own personal limits of deep air diving on someone elses limits and anyone that says they are not narced at 200ft or can deal with it are in denial.

On a side note the presentation summarizes studies on the narcotic effects of oxygen. In a nutshell the study couldn't demonstrate a less narcotic effect of divers on nitrox versus divers on air. Not relevant to this thread but interesting and backs current methodology of treating oxygen as narcotic as air when calculation END.


Dr. Bennett and Dr. Mitchell presented at the 2008 DAN Technical Diving Conference. Their presentation and references can be found in PDF form on DANs website. These PDF is available to all DAN members.

 

[phillybob]

Trimix, schmimix !! The funniest thing about this thread is how some posters don't know how to spell 'macho' or use it properly in a sentence.

 

[JeffG]

Oh, I love the black suited DIR/Tech Diver statements that "If you don't dive on Tri Mix your stupid".

Reading comprehension isn't your gig, is it?

And you wonder why you all get such a bad rap from the rest of the scuba community.

and you are doing a good job for your group.

 

[JeffG]

Trimix, schmimix !! The funniest thing about this thread is how some posters don't know how to spell 'macho' or use it properly in a sentence.

wow. Thanks for the contribution.

Please post more often.

 

[Puffer Fish]

It's 2010. We have a whole year of Deep Air threads to look forward to.

I sure hope not.

 

[JeffG]

I sure hope not.

Come on...It gives you something to do.