Really understanding Nitrogen narcosis

[Blackwood]

Whenever I dive on air deeper than about 35m I force myself into a routine, look around, check buddy position, check SPG, check computer especially dive time and remaining no-deco time and then keep cycling this routine.

Sorry for the hijack, but any particular reason you emphasized dive time and no-deco time more than SPG?

 

[CamG]

Greetings Deefstes and narcosis is a important consideration. It is very important to understand that its effects can vary day to day, dive to dive. There have been some very good threads on narcosis if you do a search they should pop up.
Learn and research as much as you can then gradually build your personal experience.
Always dive / train safe with a instructor or experienced dive buddy to watch and monitor your behavior. I have had some really funny videos that when watched post-dive are unbelievable. But as all will attest the camera does not lie! It has taught me to plan dives very carefully taking into consideration how narcosis affects me personally.
I have found that KISS theory to be right on the money, and your dive buddy is golden!
Have fun training and have a experienced diver shoot some video, I am telling you the dive on film might be better than the one you thought you were on! Ha! Ha!
Dive safe and train hard, that is the fun of it!
CamG Keep diving.....keep training....keep learning!

 

[TSandM]

I think what has really hit me is the number of times that we do a dive plan in a class that says, "Drop and do S-drills, and then valve drills, and then X leads off and we do kicks, and then . . ." On land, I have no difficulty remembering a sequence of activities like this at all, but I have repeatedly found myself unable to remember what comes next underwater. It's subtle, but I know how my mind works and what my strengths and weaknesses are under normal circumstances, and my stupidity underwater has repeatedly frustrated and puzzled me. I'm not saying I have any proof that it's narcosis, but it makes me suspicious.

 

[eponym]

TSandM, thanks for that. I feel the same. I can slyly drop a poker chip on on a dive, intending to look for it on the way back as a check on my student's navigation progress, and then completely forget to look for it later because other notions (feedback, next-dive planning, what have you) have displaced it.

I discussed this once, a few years ago, with someone who teaches rebreathers. He said it might be my relative inexperience, everything being so new and all (less than 500 dives). Or I might be more narc-sensitive.

He said one way to discover this is to descend on trimix, then take a few breaths off a tank of air at some mid-to-deep point. The narc comes on very quickly, according to him, and you can get a feel for just how impaired you would be on an air dive at that depth.

-Bryan

 

[miketsp]

Sorry for the hijack, but any particular reason you emphasized dive time and no-deco time more than SPG?

In my case I have a very low SAC and even when diving Nitrox I will often be running up a fair deco requirement and still get back on the boat with more than 1/2 tank.
I don't remember the last time I ended a real dive with 50 bar or less. By real dive I'm excluding some very long shallow dives.
So NDL or how much deco I'm prepared to pay is normally my controlling factor and not remaining gas.

WRT dive-time specifically I try to do a little mental arithmetic to check the increment from the last time I looked at it.

 

[captain]

I am completely convinced that narcosis begins when one's head goes underwater. I am a very bright woman, and the number of times I've forgotten the sequence of drills, or gotten turned around with navigation (even on shallow dive) has convinced me that there is something that affects my thinking almost immediately, and it's certainly noticeable at 30 to 45 feet. I don't FEEL any different from normal -- I just have a lot of data points of forgetfulness and confusion underwater that I don't experience doing ANYTHING on land.

Just as a hypochondriac can can transform a minor pain into a major illness in his mind it may be that the emphasis on narcosis from training or others causes you to focus on and be more aware of the mistakes you make underwater than on the surface and attribute narcosis as the reason for the mistakes.
The power of suggestion can be a factor. Your opening statement and self admitted risk adverse personality adds some validity to my thinking.

 

[Walter]

I once dated a woman who was narced on the boat.

 

[beester]

I once dated a woman who was narced on the boat.

She must have been a real daisy... any story behind this one