Exactly how deep is "Deep Air?"

[TSandM]

Not surprisingly, I put END > 100.

When I was a new diver, I had two episodes of frank hallucinations at about 100 feet. Now, this is also in very cold water and very poor viz, which is a setup for any problems to be magnified.

As time went on, I occasionally went down to 100 feet again without any similar issues, so I began to think that maybe I had either gotten used to depth or just had more bandwidth available to function at that depth.

Then I took my Cave 2 class, and watched the incredibly stupid errors I made in the 95 foot range -- errors that, in one case, could have killed me and my entire team (and this was NOT a contrived situation!) As Pete would put it, my "bovine index" was simply unacceptably high. Now, again, that's in the dark, and while swimming fairly hard, so there were contributing factors, but still . . .

The final experience was an odd one, though. I did the same wreck dive in the Red Sea three times. Twice, I was on 32%, and went to about 100 feet. The other dive (which was the middle one) was on 21/35, and the depth was considerably more. On both 32% dives, I thought the wreck was boring, because it was all grey -- there was no color to speak of at all. On the trimix dive, I was amazed to discover that the wreck was BEAUTIFUL -- covered in sponges and soft corals and decked with lionfish and other colorful inhabitants.

Now, the ability to perceive color may not be important for safety, but for me, it's a marker of how significantly narcosis is affecting my ability to process input correctly. So it's helium in the gas below 100 feet for me, and maybe even at slightly shallower depths in a cave.

 

[AfterDark]

I don't intend to speak for DCBC but I suspect his attitude is similar to mine on this subject. We started diving when air was the only gas available to rec divers and we dived safely for decades on air. Now trimix is available to us and if aren't using we are told we are doing something wrong and dangerous. I suppose it's like telling someone they are putting themselves in danger by driving on bias ply tires rather that radials. I'm too old of a dogfish at this point to bother with trimix, I'll dive safely to the finish line (old age) on air thank you very much.

 

[The Chairman]

I've only been diving since 1969... what would I know?

FWIW, NASCAR was very slow to adapt to Radial Tire technology. I think they still held desperately on to the old technology until 1992 or so. Now it's impossible to find a NASCAR team running biased ply tires. So while some may actively resist their use AND incorrectly assert why many of us switch, the inevitable conclusion is that Helium is making great strides for a simple reason: we see it as a far better solution to diving drunk.

 

[Cave Diver]

If the dive is above 150', I will usually do the dive on air, regardless if Helium is available. Between 150-200' I'll use air unless the dive is long and strenuous and Helium is available. Below 200', I prefer to use Helium but will dive air if the dive is relatively short and not strenuous. I will only use Helium over 250'. I have used air in a chamber to 300' as a test subject. The results of my performance convinced me to limit my maximum depth on air to 250' (for short periods).

For me the choice of gas has to do with the planned length of the dive, the level of exertion expected, the complexity of the dive at depth and the depth itself. Obviously the availability of Helium is also a factor.

Are you talking about commercial diving, or recreational SCUBA diving?

 

[boulderjohn]

I found the way the poll was set up in ranges a bit confusing, since the question seemed to be more about a specific depth at which you think it begins to be a factor than a range in which it is a factor. I voted as if narced and probably would change that vote given another chance.

As others have said, I have never been in a situation where I felt as if I were narced, but I have had a number of situations in which it was evident I was narced, despite not feeling it. The most clear cut of those "I feel great--why am I acting so stupid?" moments came at only about 100 feet, which gives me very little faith that keeping ENDs to the 100 foot level ensures that we will make safe and smart decisions at greater depths.

Like TSandM, I found myself doing not-so-intelligent things during my first cave training at about 95 feet, and I felt narcosis was a contributing factor. On the other hand, when I later completed my full cave certification, I found I was a lot smarter and competent doing those same tasks at those same depths. To me that is an indication of what has been said in other threads about this: narcosis becomes a more limiting factor when the diver is doing unfamiliar tasks.

 

[Trace Malinowski]

Not surprisingly, I put END > 100.

When I was a new diver, I had two episodes of frank hallucinations at about 100 feet. Now, this is also in very cold water and very poor viz, which is a setup for any problems to be magnified.

As time went on, I occasionally went down to 100 feet again without any similar issues, so I began to think that maybe I had either gotten used to depth or just had more bandwidth available to function at that depth.

Then I took my Cave 2 class, and watched the incredibly stupid errors I made in the 95 foot range -- errors that, in one case, could have killed me and my entire team (and this was NOT a contrived situation!) As Pete would put it, my "bovine index" was simply unacceptably high. Now, again, that's in the dark, and while swimming fairly hard, so there were contributing factors, but still . . .

The final experience was an odd one, though. I did the same wreck dive in the Red Sea three times. Twice, I was on 32%, and went to about 100 feet. The other dive (which was the middle one) was on 21/35, and the depth was considerably more. On both 32% dives, I thought the wreck was boring, because it was all grey -- there was no color to speak of at all. On the trimix dive, I was amazed to discover that the wreck was BEAUTIFUL -- covered in sponges and soft corals and decked with lionfish and other colorful inhabitants.

Now, the ability to perceive color may not be important for safety, but for me, it's a marker of how significantly narcosis is affecting my ability to process input correctly. So it's helium in the gas below 100 feet for me, and maybe even at slightly shallower depths in a cave.

Some years ago, a girl was doing her "deep dive" for her advanced open water class at Dutch Springs. Her instructor was Cal Azzouni, the owner of Village Divers, in NYC. They descended a line that led to a submerged car at 95 feet. The line has since been removed in favor of a shallower site. On the bottom, the girl thumbed the dive because she thought she was severely narced. She thought she was hallucinating because she saw a diver at that depth without any tanks.

At the surface, Cal was both amused and annoyed. He was amused because of the girl's reaction to seeing me freedive, but annoyed at me because he had to repeat the dive since she wanted to head to shore and regain her composure.

 

[boulderjohn]

I thought people would be interested in hearing about a rare phenomenon, the antithesis of nitrogen narcosis. It happened to me just last week.

It comes when you are forced by a set of circumstances beyond your control, coupled with a "should have planned for this" brain lapse, to do a series of shallow dives on 45% helium. You lose all focus during the dives because you are distracted by hallucinations of dollar signs flying away while you are diving.

 

[super7]

I thought people would be interested in hearing about a rare phenomenon, the antithesis of nitrogen narcosis. It happened to me just last week.

It comes when you are forced by a set of circumstances beyond your control, coupled with a "should have planned for this" brain lapse, to do a series of shallow dives on 45% helium. You lose all focus during the dives because you are distracted by hallucinations of dollar signs flying away while you are diving.

 

[ianr33]

I thought people would be interested in hearing about a rare phenomenon, the antithesis of nitrogen narcosis. It happened to me just last week.

It comes when you are forced by a set of circumstances beyond your control, coupled with a "should have planned for this" brain lapse, to do a series of shallow dives on 45% helium. You lose all focus during the dives because you are distracted by hallucinations of dollar signs flying away while you are diving.

I can relate to that

Did a cavern dive last year in JB on 21/35 after getting blown out on the Oriskany. Max depth was something like 55 feet

 

[Superlyte27]

I thought people would be interested in hearing about a rare phenomenon, the antithesis of nitrogen narcosis. It happened to me just last week.

It comes when you are forced by a set of circumstances beyond your control, coupled with a "should have planned for this" brain lapse, to do a series of shallow dives on 45% helium. You lose all focus during the dives because you are distracted by hallucinations of dollar signs flying away while you are diving.

LOL perfect