How do you learn your narcosis depths? Gas switches?

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Lots of research using Boone's Farm, MD 2020, and cold duck to discover what the onset of narcosis may feel like.
 
I learned (am still learning) to recognize the early onset of narcosis by accidentally taking a much larger narc than intended. I got WAY too damn high at about 140’ breathing air and working too hard; I believe CO2 was a huge factor. After that one particular incident I’ve been much more aware of the symptoms creeping in. I also don’t dive past 130’ without helium anymore.

Not that I would know, but I’ve heard that the effects are very similar to Nitrous Oxide, maybe your dentist can hook you up with a good hit for experience
 
My first thought when I read the post was an analogy......

would you practice driving drunk to see how it affects you? A bit tongue in cheek but still.....

certainly dives that are layered in good choices for safety could be used as tests for narcosis affects...but there are so many variables that any results would be highly anecdotal.

Best to use air/Nitrox for 100’ dives or less and throw some He in there when deeper. Several progressive agencies use an EAD of 100’ for a reason.

My dives are consistently cold and lower viz. I’m going to use an END of 100’ with He. And 32% to 100ft. Makes sense for me, regardless of what the agencies do.
 
I'd like to skip rehashing the getting good at working on narcotic gases debate! It has been well hashed.

I'd rather we focus on how you find the depths at which we are affected (for the local conditions, activity level and good respiration rate).

If I understand your intent, I don't know how to separate these two. The only way to discover your narcosis tolerance is to experience it, progressively and deliberately. Nitrogen narcosis is a very slow continuum, not a binary switch. The first step is learning the to deal with the second huge variable, CO2. You know the difference by deep and slow hyperventilation. The influence of CO2 goes away almost immediately. NN doesn't until you ascend. For me, hyperventilation is on the order of 6 to 8 breaths per minute — sort of like the beginning of a freediving breath-up.

I find the alcohol analogy very misleading. The relaxed to blind drunk progression is much different and few if any people experienced with NN get blind drunk. I would describe the progression of NN more like slightly distracted, like driving in a light rain, to driving in a snow blizzard. This is still not a great analogy but closer and more linear that with alcohol.

Our senses are "impaired" the moment we hit the water, from all the gear and different stimulus. We learn to manage it fairly quickly. The same thing happens with NN, which makes it a moving target in the beginning.
 
If I understand your intent, I don't know how to separate these two. The only way to discover your narcosis tolerance is to experience it, progressively and deliberately. Nitrogen narcosis is a very slow continuum, not a binary switch. The first step is learning the to deal with the second huge variable, CO2. You know the difference by deep and slow hyperventilation. The influence of CO2 goes away almost immediately. NN doesn't until you ascend. For me, hyperventilation is on the order of 6 to 8 breaths per minute — sort of like the beginning of a freediving breath-up.
It would have been more accurate for me to say I'd rather skip the "you can work/dive just fine narc'd heavy/moderate/light" discussion. Working just fine because you breathe better, so have less CO2, so are not narc'd, is good to know.

What about hanging at a depth for 5 minutes without He, seeing how you feel, then switching to He for 5 minutes and seeing if there is a difference? Then, if no difference, back to no He but breathing shallow, then switching to He and doing the same? So one depth, two different conditions of breathing, two gasses to see He effect.

Now, you could ascend for the lower END condition, but a gas switch would help keep the other variables the same (like cold and dark), and better replicate the final condition of He at that depth not staying higher on non-He. Which requires safe gas switches for that depth.
 
It would have been more accurate for me to say I'd rather skip the "you can work/dive just fine narc'd heavy/moderate/light" discussion. Working just fine because you breathe better, so have less CO2, so are not narc'd, is good to know.

What about hanging at a depth for 5 minutes without He, seeing how you feel, then switching to He for 5 minutes and seeing if there is a difference? Then, if no difference, back to no He but breathing shallow, then switching to He and doing the same? So one depth, two different conditions of breathing, two gasses to see He effect.

Now, you could ascend for the lower END condition, but a gas switch would help keep the other variables the same, and better replicate the final condition of He at that depth, not staying higher on non-He. Which requires safe gas switches for that depth.

It sounds to me like you are not understanding how narcosis works. If you hang motionless, at depth X and do absolutely nothing and breath air and then switch to some mix, the chance of you seeing much difference is pretty low. If a diver has all the diving activities down and can handle them without much conscious thought or effort, then if they are doing "nothing" narcosis is not going to be very evident.

If you want to determine the impact of narcosis, then you have to do things. You need to swim and get your heart rate up, you need to try to solve some kind of novel problem. The impacts are going to be much, much more evident in that type of scenario.

In addition, what value does testing yourself hanging on a descent line at 160 feet doing nothing - unless that is the only thing you expect to do on a real dive to that depth? As has been emphasized, work load is a critical factor. Here's an idea to see how well you function:

Drop down to 150 or 180 feet and swim real hard for 60 seconds, then stop and chill and see how you feel. Chances are your lips and tongue may be numb and your breathing will seem really loud and you will probably feel pretty buzzed. Do that a few times and you will realize it is probably something to avoid. Unless you are super deep or super susceptible, it is exertion and unique problem solving difficulties that are going to bite you in the azz.. not going 15 feet past some recommended depth limit.

Learning to manage work load, breathing efficiency and remembering you are impaired at depth (in other words, second-guess and carefully consider all your decisions) are "skills" you need to develop to dive deeper on air (and hope to come up).
 
What about hanging at a depth for 5 minutes without He, seeing how you feel, then switching to He for 5 minutes and seeing if there is a difference? Then, if no difference, back to no He but breathing shallow, then switching to He and doing the same? So one depth, two different conditions of breathing, two gasses to see He effect. Which requires safe gas switches for that depth.

I doubt that will tell you very much unless you are very deep, like well in excess of 200'/60M. You really need a challenging task to focus on and a means of measuring impairment at more reasonable depths. Marco photography can be very effective tool (except for point & shoot configurations). You can analyze evidence of impairment yourself on the surface. You will remember struggling with camera settings more than when shallow. You can also see changes in impairment as you learn to manage it.

Narcosis is less about how you feel than how you think and analyze. The feeling part of narcosis is reflected in sensory perception. Inexperienced divers tend to get a little silly and jovial in chambers but that also happens at 60' to a lesser extent due to the new experience. The trouble is that personality changes like this are really hard to detect in yourself in real time. I do feel excessive CO2 fairly dramatically and can turn it on and off. You can get that experience at 60' if you work at it hard enough.

Remember my story of repeatedly making dives on air and HeO2 at 165'/50M?

I have had the opportunity to dive air and HeO2 to the same depth up to 4 times per day, alternating air and mix on different dives. The depths were in the 165'/50M range and we were on open-circuit Scuba. It got to the point where we had trouble telling the difference between a mix and air dives except for being colder.
 
What about hanging at a depth for 5 minutes without He, seeing how you feel, then switching to He for 5 minutes and seeing if there is a difference? Then, if no difference, back to no He but breathing shallow, then switching to He and doing the same? So one depth, two different conditions of breathing, two gasses to see He effect.

I think a better experiment would be to do two dives, one on nitrox/air and one on mix.
 
If you want to determine the impact of narcosis, then you have to do things.
Thanks. Hang was incomplete, again..., sorry. It would have been rather boring as well. Putter around the reef in that area would have been more accurate of my meaning. I would have at least been examining the environment around me and seeing if there was a difference in my awareness.

But better is some task or also physical workload. Darting back and forth along the reef. Or, an invertebrate survey on a slate plus seeing if that required me to loose more focus of what else is around me. Or if managing tallies was had. Or, reviewing the next parts of the dive plan on a slate, and seeing if they confused me.

Learning to manage work load, breathing efficiency and remembering you are impaired at depth (in other words, second-guess and carefully consider all your decisions) are "skills" you need to develop to dive deeper on air (and hope to come up).
My intent is mostly around not diving on air, but on light trimix. But of understanding where that level of concern occurs for me and factors contributing to it. Not just papering over it with He. And this is all in the recreational range, for me.

Marco photography can be very effective tool
Maybe I need to take up macro photography, though invert surveys might have to suffice at first. My cautiousness on narcosis is from knowing I was confused by my computer in the past, in the 80-100' range.

Remember my story of repeatedly making dives on air and HeO2 at 165'/50M?
Yes, which I read as highlighting breathing. And possible getting used to the task? Right, ok, so you really need a task. While at the 200' range breathing was not enough to prevent effects, but is well past rec range, though individual effects vary.

I think a better experiment would be to do two dives, one on nitrox/air and one on mix.
What comparison would I make between the two?
 
https://www.shearwater.com/products/perdix-ai/

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