How do you learn your narcosis depths? Gas switches?

[Centrals]

CCR is likely eventually. For now I'm sticking with the simpler open circuit with some dives venturing into the narcosis realm. I'd rather know that I can as I go there, and got a rec trimix cert for that. My deep qual was a while ago, so I've forgotten what that may have felt like on air. And separating that from the unfamiliar, cold, and dark. Reliving it without mix handy seems a bit like driving drunk to remember, but without an offramp for the drunk, to reuse an analogy.

I believe we all feel differently under narcosis.
For me I have learnt what might trigger it so I stick to my routine.
But most importantly recognize the initial onset and react accordingly. Always check with buddy especially in tec dive to make sure every one is fine.

 

[Scuba Client]

How many precious min do you get from using EAN24 over EAN21?
No I won't bother.
Switch to CCR and use trimix!!!

Depends, if you have your own boat you can dive longer with any configuration. If you can afford to run a CCR, go with it.

 

[ChuckP]

From my experience one can, however it takes a good mentor and practice. First I assume I am impaired past 100'. It is not easy to describe, nor will I be able to accurately know how impared I am, but I did learn when to quit. I do work up dives before going deep to practice and gauge my abilities, and insure my breathing won't work into a CO2 hit, which only makes matters worse. Without work up dives I won't break rec limits.



A CO2 hit is not nitrogen narcosis. The symptoms of narcosis are stupidity and narrowing of focus, neither of which are easy to determine on your own, and unlike alcohol, you will have no physical clues of your condition.

First you say you can tell when you are impaired, but you can't tell how impaired you are but you know when to quit but then you reply to me that it isn't easy determine impairment on your own......

I call a CO2 hit something that results from dramatic over excertion or a CCR scrubber failure of some sort - the ppCO2 in your blood elevates, your brain tells you to breathe more but you can't breathe enough thru the regulator or due to the scrubber failure - a CO2 hit to me can result in a cascading event with a bad outcome.

What I call CO2 buildup is as the gas density increases from diving deeper, it becomes more difficult for us to exchange the volume in our lungs or you had short burst of excertion - all while doing shallow breathing that some of us do to conserve gas. (I dive in Cozumel where it is very rare for me to do any work underwater, I smoke, I shallow breathe a lot because diving here for me is no more effort than laying on a couch) This slight buildup of CO2 does produce a narcotic effect - CO2 has a narcotic effect way greater than Nitrogen - read the attached article - is it really 25x more narcotic or not is science mumbo jumbo.

If I do a long drift dive at say 120' for 20-30 minutes and shallow breathe the whole time, I can feel the change as it happens, it's gradual but there. I can take deper, slightly quicker breathes and feel the change reverse. I can swim head down real hard to the entrance of Devils Throat and be impaired right inside the cave opening, I can sit still for a few moments and thru breathing come back to crystal clear, I can then swim thru the cave, exit and drop over the wall to 150' and drift for a few minutes all crystal clear.... Those two examples while maybe are slight Nitrogen narcosis, they are way more CO2 narcosis. Being able to "control" the narcosis while maintaining depth tells me it's not related to Nitrogen. These are also unigue types of dives where you aren't maintaining your excertion levels - your allowing your body to come back to it's at rest state.

What do I do to check myself, I touch my thumb to my finger tips and count, back and forth, index to pinkie, pinkie to index. I check depth or air pressure. I look at things - I force myself to be aware. I think the noticing is all about noticing and accepting that there is a change in your brain and the willingness to say I can't stay here at this depth - like you said - it's something you are looking for.

This whole narcosis thing, I'm thinking it is much more related to CO2 verses Nitrogen in the vast majority of divers. Just watch divers underwater in a stressfull non working enviroment - watch their bubbles - I see a lot of mid level breathers that will have elevated breathing rates under "stress". They aren't fully "cleaning" their lung space of CO2 and the slight elevation causes the narcotic effect...... Why does the diver in lake Michigan at 120' have a rmv of .7 but yet after diving here for a week lowers that rate to .4 or .45 - they are more relaxed. Take that relaxation along with some breath control and see how it effects your narcosis levels at home diving enviroments....

I might be completely wrong and off base - I didn't stay at a Holiday Inn but I do drink Dos Equis......

And don't strike me down for this GUE reference, I couldn't find my paper that has the same graph:

Carbon Dioxide, Narcosis, and Diving.

 

[RainPilot]

My concern with all these "narcosis tests" that folks conduct (not necessarily the OP suggestions, but the kind of things done on AOW courses etc) is that they can be quite counterproductive. They are almost always done on purpose which means there is some level of mental readiness for them, often they are repeats of an exercise done on land to get a benchmark time, which means that they are being repeated and thus the time increase is reduced or sometimes they go faster, depending on how the test is designed. Often this leads to folks underestimating the effects of narcosis on them.

In regular operations, muscle memory and reflex reactions will often be enough to get you through the dive without ever feeling like you are narced. It's when something new occurs, which requires you to engage your cognitive processes, that things can go pear shaped fast. The analogy I use with students is the person who, every night, drives to a bar, has several drinks, then drives home intoxicated. Eventually, they will get quite good at driving home and will swear that they drive even better when drunk, until something unexpected happens (other car runs a red light etc) and then they are deer-in-the-headlights while their alcohol brain tries to change gears.

I suspect @Akimbo commercial diver experiences are similar to this, folks doing "routine" actions over and over and over again in training and then working, deeper and deeper as they become more qualified, until those divers can do those actions while being pretty out of it otherwise. They also have a redundant unimpaired brain on the surface talking to them which helps a great deal.

You as a recreational diver (ie not commercial) will only find out how narced you REALLY are when you encounter a sudden surprise, usually an emergency. I, personally, don't want to find out I am too "drunk to drive" at 200' plus.

 

[Vicko]

Really the only way to figure it out is experience in a lot of different environments and circumstances and to get that experience you have to expose yourself to additional risks that are not necessary to enjoy this activity.

 

[Centrals]

Depends, if you have your own boat you can dive longer with any configuration. If you can afford to run a CCR, go with it.

IF. period

 

[Bob DBF]

We are pretty much in agreement overall, from what I read.

This whole narcosis thing, I'm thinking it is much more related to CO2 verses Nitrogen in the vast majority of divers.

Although the term narcosis can be used to include any type of narcotic effect of any gas, it may give the idea that CO2 narcosis and Nitrogen narcosis is the same effect, and if one doesn't have the affects of CO2 then one is not affected by nitrogen narcosis either. The way I look at it is that CO2 can scare a diver out of the water, however nitrogen is much more subtle, one may not know how stupid they are until it's too late.

 

[Akimbo]

I suspect @Akimbo commercial diver experiences are similar to this, folks doing "routine" actions over and over and over again in training and then working, deeper and deeper as they become more qualified, until those divers can do those actions while being pretty out of it otherwise. They also have a redundant unimpaired brain on the surface talking to them which helps a great deal.

Even more important, we rehearse the job mentally before the dive — even for shallow water or deep HeO2 dives. Organization and preparation is not just for narcosis. Commercial diving can pay well so it is competitive and screwing up increases the chance that you won't be called for the next job, or sent ashore on this one. Fortunately that mindset is also essential for managing narcosis.

This is part of what I mean by working divers have a different mindset. This mindset can also be observed in professional underwater photographers and science divers. IMO, it is also the kind of mindset that makes recreational deep diving safer regardless of the depth or gas. Managing gas failures and decompression is a far more difficult than narcosis management.

There is no selection process in military or commercial diving for tolerance to nitrogen narcosis. There are thousands of us. If NN was half as debilitating as some people make it out to be, salvaging submarine F-4 on air in 306'/93M of water in 1915 would have been impossible. The 33 survivors of the submarine Squalus would also have died with their shipmates in 243'/74M of water (the rescue was on air and the salvage was on HeO2).

 

[johndiver999]

Even more important, we rehearse the job mentally before the dive — even for shallow water or deep HeO2 dives. Organization and preparation is not just for narcosis. Commercial diving can pay well so it is competitive and screwing up increases the chance that you won't be called for the next job, or sent ashore on this one. Fortunately that mindset is also essential for managing narcosis.

This is part of what I mean by working divers have a different mindset. This mindset can also be observed in professional underwater photographers and science divers. IMO, it is also the kind of mindset that makes recreational deep diving safer regardless of the depth or gas. Managing gas failures and decompression is a far more difficult than narcosis management.

There is no selection process in military or commercial diving for tolerance to nitrogen narcosis. There are thousands of us. If NN was half as debilitating as some people make it out to be, salvaging submarine F-4 on air in 306'/93M of water in 1915 would have been impossible. The 33 survivors of the submarine Squalus would also have died with their shipmates in 243'/74M of water (the rescue was on air and the salvage was on HeO2).

WOW, I generally agree with 99% of your comments, but not this one. There are many stories of people being quite incapacitated at considerable depths on air. I know of a few at "just" 180 feet. I also know of some extremely experienced scuba divers who just don't feel comfortable deep and therefore won't dive deep.

I have to think there is a relative small minority of people who are extra susceptible to narcosis (for physical and possibly psychological causes) and therefor a great deal of caution should be applied toward deep diving. The population of active commercial divers is probably younger, healthier, more fit and better trained than the population of recreational divers and I don't think it is wise to generalize their performance to the general population.

I know a few people who used to bounce down to 300 on air (for fun and alone) and they always seems to make it up, but I have to believe that these individuals where somewhat "special" in some regard.

It seems absolutely ridiculous that some people can function at 300 while others claim to be uncomfortably impaired at 100 feet, but that is the reality of the situation as far as I can tell.

 

[Akimbo]

There are many stories of people being quite incapacitated at considerable depths on air.

The context of my comments is narcosis management. Anyone who is incapacitated at any depth on air is not practicing what I preach. It doesn't matter if experience tells you not to exceed 60'/20M or 230'/70M on air. What matters is you learn where that limit is and the difference between NN and excessive CO2. Excessive CO2 can hit you at 30'/10M.

I have to think there is a relative small minority of people who are extra susceptible to narcosis (for physical and possibly psychological causes) and therefor a great deal of caution should be applied toward deep diving.

The whole idea is to approach deep diving, on air or trimix, with a great deal of caution. It is probable that a small minority of individuals who are highly susceptible to narcosis self-select, if they exist. The entire point of recreational diving is to enjoy it. Being uncomfortable is NOT enjoyable, so why dive deep enough to be uncomfortable?

A couple of divers onboard during my trip to Truk made that decision by skipping the dive to the San Francisco Maru. Nobody thought less of them and they really didn't miss that much. Don't let anyone tell you that narcosis management is easy and doesn't require a lot of work.