Deep Air - Here we go again....

[DCBC]

Gene Hobbs (from Rubicon) usually chips in a some point with a reasonably concise but highly accurate summary of the more recent scientific studies of the narcotic potency of oxygen. And then everyone will ignore Gene and get back to usually fruitless butting of heads that characterises these threads (I am still bitter about one of my threads which I tried very carefully to turn into a sensible discussion of the topic descending into the usual chaos within about 3 posts).

Gene will cut me off if I am wrong, but I believe current thinking is that oxygen is probably roughly as narcotic or slightly more narcotic than nitrogen (ie. less than its lipid solubility would suggest, but certainly more than zero). But like all scientific studies of narcosis, I think it is all pretty fuzzy (no pun intended).

I know what you mean. Oxygen narcosis isn't even the topic of this thread.

 

[Blackwood]

I believe that this is the study that Dr. David Sawatsky referred to (see my previous posting). Obviously you're not real motivated or you would have realized this. Perhaps if your motivation changes, you might read the article.

I don't have access to the full article, just the abstract. From that, it seems that they were trying to determine if nitrox blends decrease narcosis. The conclusion seems to be: no. "It thus seems that substituting O2 for some of the N2 does not ameliorate the mild narcosis. Within the limitations of the experimental design our results suggest that O2 contributes to the narcosis of hyperbaric air."

 

[Blackwood]

I know what you mean. Oxygen narcosis isn't even the topic of this thread.

Yah, but at least it's different

 

[Slamfire]

Ok so getting back to topic. I was thinking about the reasons why people's opinions of deep air are different. One that we discussed at length was different max END standards from different agencies, so I'll leave agencies out of this. Another that occurred to me, somewhat independent of agencies, is diver locations.

Last September I had a business trip to Columbus, OH. I started doing some research about diving opportunities close to Columbus. The closest one, Twin Quarries, was very shallow -- about 20 ft, no more than 30. I discarded that because for those depths I would just snorkel/freedive and I wanted to scuba.

It seemed that for my liking, the closest decent option was Gilboa. 130 ft max but most of the underwater features are above 60 or 40. Here's my log entry for the dive:

Gas Consumption = 2800 - 800 = 2000 psi
Avg. Depth = 28
SCR = 0.558 cu ft/min
The quarry felt over crowded by people, artificial wrecks, platforms and unnaturally friendly fish. Decided not to do a 2nd dive. Buddies seem to be rushing through everything, perhaps because they've dove this quarry before. There was an interesting "wall" that went to 130', but due to the novice buddies, decided against diving it. Fish = trout, bass, crappies, catfish, carp.

Now, before you accuse me of Gilboa bashing keep in mind that this is my first and only quarry dive ever. I'm used to the openness of oceans and lakes. Compared to what I am used to, being able to go from shore to shore many times in single dive just feels too crowded. I have a suspicion that in the universe of quarry diving, Gilboa could be one of the best.

I know that tech training takes place in Gilboa. It's no surprise because unless you want to do very long drives, that is the only option for people living close to it. There was no current (is it big enough to have currents?). Temps were a toasty 68 compared to my usual 46-48. Visibility was slightly higher than what I usually experience around BC. There's no waves, no tides, no surge, no boat traffic, no fishing line, no fishermen. If I were living in Columbus and Gilboa were my only way to keep my skills honed in between dive vacations of course I would want to set a low END as my max when ocean diving. I would probably even be amazed at the "irrationally" high END other people use in such a big, open, and risky environment.

 

[boulderjohn]

Reality and numbers don't always agree. Aeronautical engeering says bumble bees shouldn't be able to fly.

First of all, the story that aeronautical engineering says that bumblebees should not be able to fly is a myth.

More importantly, the numbers don't say something will happen under those conditions, they say that the likelihood that something will happen will increase under those conditions. It all comes down to making a decision as to what level of risk is acceptable. At some point, you have to agree with Damon Runyon:

The race is not always to the swift nor the battle to the strong - but that's the way to bet.

 

[hg frogman]

As far as I know, the limits set for open water air diving (for adequately qualified divers) by many training agencies or federations, including TDI, BSAC, FFESSM/CMAS and even DSAT are in the 50 to 60 meters range (165 to 200 feet).

Same for commercial diving with air.

The distinction between "recreational" and "technical" diving is American, not European, though Europeans know what "technical diving" means.

Most of the adequately qualified and trained French divers (me included) don't consider as "technical" an open water air dive down to 50 meters, which is common practice in France when conditions are right, with a 15 liters tank on one's back and that's it. Call it "macho" if you like ; "overkill" isn't any nicer and has drawbacks of its own.

 

[Sloth]

Ok so getting back to topic. I was thinking about the reasons why people's opinions of deep air are different. One that we discussed at length was different max END standards from different agencies, so I'll leave agencies out of this. Another that occurred to me, somewhat independent of agencies, is diver locations.

Last September I had a business trip to Columbus, OH. I started doing some research about diving opportunities close to Columbus. The closest one, Twin Quarries, was very shallow -- about 20 ft, no more than 30. I discarded that because for those depths I would just snorkel/freedive and I wanted to scuba.

It seemed that for my liking, the closest decent option was Gilboa. 130 ft max but most of the underwater features are above 60 or 40. Here's my log entry for the dive:

Now, before you accuse me of Gilboa bashing keep in mind that this is my first and only quarry dive ever. I'm used to the openness of oceans and lakes. Compared to what I am used to, being able to go from shore to shore many times in single dive just feels too crowded. I have a suspicion that in the universe of quarry diving, Gilboa could be one of the best.

I know that tech training takes place in Gilboa. It's no surprise because unless you want to do very long drives, that is the only option for people living close to it. There was no current (is it big enough to have currents?). Temps were a toasty 68 compared to my usual 46-48. Visibility was slightly higher than what I usually experience around BC. There's no waves, no tides, no surge, no boat traffic, no fishing line, no fishermen. If I were living in Columbus and Gilboa were my only way to keep my skills honed in between dive vacations of course I would want to set a low END as my max when ocean diving. I would probably even be amazed at the "irrationally" high END other people use in such a big, open, and risky environment.

I moved to ohio from hawaii just recently. Why you got to point out the depressive nature of local diving around here :mooner:

But to the defense of local diving some of the best wreck diving is in the great lakes or so i am currently telling myself.

It's really all subjective. As mundane as you found quarry diving (as i'm sure i will) you would be amazed at the number of diver deaths that Gilboa claims. Besides, narcosis is as much dependent on internal stressors as external stressors. A diver could find himself in as stressful of a situation at 100' in a quarry as he can at 150' in the ocean and while external conditions are a cumulative factor it's not the only variable in stress induced narcotic panic.

Thanks but i'll stick with my END of 100' on the tech dives regardless of how conditioned i am to the local environment.

 

[PfcAJ]

Yes, nitrogen narcosis can be a problem, but don't make it into the Boogy Man that's the leading cause of death for divers. IT'S NOT. Yes it's a factor, but get real.

Even more inappropriate is to suggest that the reason why they died had anything to do with the END.

I wish you would pick a position...

 

[Slamfire]

As far as I know, the limits set for air diving (for adequately qualified divers) by many training agencies, including TDI, BSAC, FFESSM/CMAS and even DSAT are between 50 and 60 meters (respectively 165 and 200 feet).

Some posts ago in this thread I mentioned several times that in the Americas the accepted limit of non-tech recreational scuba is 130 ft. I failed to mention that the accepted limits in Europe were even deeper. It also seems that in Europe the scuba community is not as affected by labels like "technical diving".

Diving is still a (relatively) free world

I feel very privileged to live in a country were diving is not regulated and I am free to do whatever I want when it comes to my diving practices, particularly when some people equate diving "deep air" to suicide or playing Russian Roulette.

 

[Rhone Man]

Some posts ago in this thread I mentioned several times that in the Americas the accepted limit of non-tech recreational scuba is 130 ft. I failed to mention that the accepted limits in Europe were even deeper. It also seems that in Europe the scuba community is not as affected by labels like "technical diving".

I could be wrong, but I think BSAC treats air down to 150 feet as recreational.

What I definitely think is true is that in Europe people are much more open to going deeper. When I was in Cyprus we were popping down to 140 feet, and no one thought much of it. There was another dive on the menu (which I didn't do) that went to 160 feet, and no one was asking for technical certifications or wearing doubles.

The term 'technical diving' is well understood in Europe, but they often just regard that 130 - 160 foot band as 'advanced' rather than technical.