When I did my deep water training, the instructor asked me to perform one of those time measured exercises (you know, dexterity or "mind exercise" ) on the boat and again at 40 meters deep. On boat, I did it in 50 sec and at the bottom I manage to do it in only 36 sec. But doesn't mean I wasn't or I will not be hit by narcosis somewhere in the future. As you know, you could dive for 100 times and no narcosis, but one day, in exactly same conditions and even a shallower dive you could start talking with fishes
Nitrogen Narcosis.
- Thread starter Tekk Diver
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When you're stupid, it's usually pretty difficult to realize that you are stupid (cue Dunning and Kruger). I'm pretty convinced that impairment due to nitrogen narcosis starts a lot earlier than most of us realize.
Since an uneventful dive in easy conditions is something which we have a bit of training and routine in, a little bit of stupid doesn't affect us. Routine issues don't require much mental bandwidth to handle, so a slight loss of that bandwidth won't be noticeable. So we can feel fine at 40m - or deeper - as long as everything goes well. We're still impaired, it just doesn't have much of an effect. Yet... However, the more unfamiliar we are with a situation, the more mental bandwidth is needed to handle it. So if the bovine manure intersects with the air conditioning system, we're not as well equipped to handle that situation even if we're just slightly narked, and if there is an emergency we haven't prepared and trained for, we may very well be pretty far up that proverbial creek in a way we wouldn't be if we weren't impaired.
My job is occasionally rather intellectually demanding, so I have quite a bit of experience in recognizing those small indications that my brain isn't turning around at full speed. Whether it's due to a generally bad day, a poor night's sleep, or a single beer. Yes, one single beer dulls the brain and makes most of us think slower. And with that "training" I'm able to sometimes realize that my mental processes are dulled even at depths shallower than 30m. So, since I hate being stupid I've set my personal depth limit at around 30m. Besides, around here the light is really crappy at those depths, and I'm not a wreck diver, so I don't have many reasons to go significantly deeper. When I'm fully occupied with keeping my depth and trim only a few cm off the bottom without touching it, while at the same time composing a pic, operating my camera and positioning my strobes and also keeping tabs on my buddy, I can notice the nark even at depths above my personal limit. Even if I don't notice it when I and my buddy are swimming leisurely side by side over the same spot at the same depth, my camera just dangling from one of my hands.
Although I believe that nitrogen affects different people differently, I have a very hard time believing those who claim that they can dive to 40-50m or even deeper without being narked. IMO they're either lying, or they just don't realize it.
Since an uneventful dive in easy conditions is something which we have a bit of training and routine in, a little bit of stupid doesn't affect us. Routine issues don't require much mental bandwidth to handle, so a slight loss of that bandwidth won't be noticeable. So we can feel fine at 40m - or deeper - as long as everything goes well. We're still impaired, it just doesn't have much of an effect. Yet... However, the more unfamiliar we are with a situation, the more mental bandwidth is needed to handle it. So if the bovine manure intersects with the air conditioning system, we're not as well equipped to handle that situation even if we're just slightly narked, and if there is an emergency we haven't prepared and trained for, we may very well be pretty far up that proverbial creek in a way we wouldn't be if we weren't impaired.
My job is occasionally rather intellectually demanding, so I have quite a bit of experience in recognizing those small indications that my brain isn't turning around at full speed. Whether it's due to a generally bad day, a poor night's sleep, or a single beer. Yes, one single beer dulls the brain and makes most of us think slower. And with that "training" I'm able to sometimes realize that my mental processes are dulled even at depths shallower than 30m. So, since I hate being stupid I've set my personal depth limit at around 30m. Besides, around here the light is really crappy at those depths, and I'm not a wreck diver, so I don't have many reasons to go significantly deeper. When I'm fully occupied with keeping my depth and trim only a few cm off the bottom without touching it, while at the same time composing a pic, operating my camera and positioning my strobes and also keeping tabs on my buddy, I can notice the nark even at depths above my personal limit. Even if I don't notice it when I and my buddy are swimming leisurely side by side over the same spot at the same depth, my camera just dangling from one of my hands.
Although I believe that nitrogen affects different people differently, I have a very hard time believing those who claim that they can dive to 40-50m or even deeper without being narked. IMO they're either lying, or they just don't realize it.
DevonDiver
N/A
The sort of exercises used by many recreational 'deep' instructors are very ineffective at illustrating narcosis issues. Performing them first on the boat also means they are not novel when later performed at depth.
One of the major barriers to effective understanding of the insidious effect of narcosis is the tripe regurgitated by some recreational instructors who, themselves, have no real understanding or concept of the malady.
What's worse, is that their own deficit of understanding leads to flawed education that allows some (many?) divers walking away from "deep" training believing they conducted tests that proved they were unaffected.
The Chairman
Chairman of the Board
So, you had some practice first. You were able to figure out how to do it before you got impaired. I would be more surprised if that didn't help you significantly.
The reason training is so important is so that we get to practice before we get impaired. That's great for any anticipated failures or situations but does little to prepare us for those that blind side you. Even a cow can follow a trail down to the watering hole. Start making is complicated and the cow's gonna go thirsty. The deeper you go, the more you act like a cow. While a cow can endure being thirsty for a long time, our time to resolve an issue is limited by our air supply.
absolutely agree Storker
and again
absolutely agree DevonDiver.
It was exactly my point. Considering you're not hit by narosis because you manage to perform God knows what hocus-pocus exercise and next time go even deeper because you are "invincible" just proves you didn't understand the basics of diving
and again
absolutely agree DevonDiver.
It was exactly my point. Considering you're not hit by narosis because you manage to perform God knows what hocus-pocus exercise and next time go even deeper because you are "invincible" just proves you didn't understand the basics of diving
NetDoc please don't get me wrong. It wasn't my intention to plead for the idea "the narcosis hits everybody except me". On the contrary! I'm absolutely convinced that I was narked, despite that I didn't feel it and I did perform that stupid exercise. I never go deep just for the sake of a record and even for a dive at 30 meters I plan everything keeping in mind the idea my brain will be slow than usual and much more predisposed to mistakes
packrat12
Contributor
Wow what an old thread... But still relevant.
We really need to stop thinking about Narcosis as Nitrogen Narcosis. I like the term Inert Gas Narcosis as it better describes what may be happening, although I tend to refer to it as just Narcosis. I have stopped using the word Nitrogen in the description.
I personally suspect that the moment we hit the water and start increasing our pressure, we are 'feeling' the affects of narcosis. This does not matter if we are at 33' or 99'. As we go deeper, we are going to feel more effects. We all will have a personal level of threshold that will allow us to detect if we are "narc'd". We all will differ on what tasks we can do and accomplish for a given level of "narc'd". I have said in previous posts that I have done air at 175' without being "narc'd". The real statement should be that the effects were not apparent for my task loading. Switch gas to trimix, I reduce the N2. I should, for the same conditions, be less "narc'd" then on air. Add into the trimix equation issues which raise work load, task load and complexity and we may have a different story. I did the same dive and was very "narc'd" while on trimix. The new factor was CO2 which is 25x more narcotic then N2. Now, had I been on air, I may not have been functional but remained functional as I was on trimix. It is also possible that the CO2 was such a factor that using either gas, I would have been just a little more "narc'd" using air vs trimix. If you look at the lipid solubility, you will find that He and N2 are very close together. At the same time, CO2 is very far away, albeit in much less concentration in our blood stream.
Getting through a test for being "narc'd" is not what is important. It is understanding what processing you are doing to get through it. If you are needing to work more, think more, double check more, etc - then it is a good indication that you are "narc'd". I would suspect that if we did very complex tasks (orbital mechanics or such), we would find that even at 33' - 66', we are more "narc'd" then we think. Can I feel 1 beer - yes. Can I feel narcosis - yes. Can I ignore and write it off, especially at shallower depths - yes. As it impairs more automatic responses, eventually it should dramatically show effects on us. Being tuned to your performance and reasons for it, can help show when narcosis is affecting you. Just like being drunk, there is a point at which required functionality may not exist any longer. Some may define this as when they are "narc'd". I personally do not have a depth floor. I know that personally by 125' I am aware of it but even for a given workload, was not impaired at 175'.
Two interesting articles:
Carbon Dioxide, Narcosis, and Diving
Carbon Dioxide, Narcosis, and Diving | Global Underwater Explorers
Moving in extreme environments: inert gas narcosis and underwater activities
Moving in extreme environments: inert gas narcosis and underwater activities
We really need to stop thinking about Narcosis as Nitrogen Narcosis. I like the term Inert Gas Narcosis as it better describes what may be happening, although I tend to refer to it as just Narcosis. I have stopped using the word Nitrogen in the description.
I personally suspect that the moment we hit the water and start increasing our pressure, we are 'feeling' the affects of narcosis. This does not matter if we are at 33' or 99'. As we go deeper, we are going to feel more effects. We all will have a personal level of threshold that will allow us to detect if we are "narc'd". We all will differ on what tasks we can do and accomplish for a given level of "narc'd". I have said in previous posts that I have done air at 175' without being "narc'd". The real statement should be that the effects were not apparent for my task loading. Switch gas to trimix, I reduce the N2. I should, for the same conditions, be less "narc'd" then on air. Add into the trimix equation issues which raise work load, task load and complexity and we may have a different story. I did the same dive and was very "narc'd" while on trimix. The new factor was CO2 which is 25x more narcotic then N2. Now, had I been on air, I may not have been functional but remained functional as I was on trimix. It is also possible that the CO2 was such a factor that using either gas, I would have been just a little more "narc'd" using air vs trimix. If you look at the lipid solubility, you will find that He and N2 are very close together. At the same time, CO2 is very far away, albeit in much less concentration in our blood stream.
Getting through a test for being "narc'd" is not what is important. It is understanding what processing you are doing to get through it. If you are needing to work more, think more, double check more, etc - then it is a good indication that you are "narc'd". I would suspect that if we did very complex tasks (orbital mechanics or such), we would find that even at 33' - 66', we are more "narc'd" then we think. Can I feel 1 beer - yes. Can I feel narcosis - yes. Can I ignore and write it off, especially at shallower depths - yes. As it impairs more automatic responses, eventually it should dramatically show effects on us. Being tuned to your performance and reasons for it, can help show when narcosis is affecting you. Just like being drunk, there is a point at which required functionality may not exist any longer. Some may define this as when they are "narc'd". I personally do not have a depth floor. I know that personally by 125' I am aware of it but even for a given workload, was not impaired at 175'.
Two interesting articles:
Carbon Dioxide, Narcosis, and Diving
Carbon Dioxide, Narcosis, and Diving | Global Underwater Explorers
Moving in extreme environments: inert gas narcosis and underwater activities
Moving in extreme environments: inert gas narcosis and underwater activities
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