How much narcosis is acceptable/'normal'?

[Jheard89]

For me, the deeper I go the LESS narcosis is acceptable. I am probably not going to get my undies in a twist diving air or nitrox at 40m = END 40m

If I'm at 80m there's no way I want an END of 40m, that's crazy. (and the density guidelines support this). The consequences of not having a clear head are way more severe. By 60m I want ENDs <25m, at 80+m I want ENDs around 20m max.

Yea I feel like I'm at the limit of my comfort zone diving to 45/50m without helium.

I'm interested to know how you came to these specific ENDs at these depths? Is this something you've applied to yourself based on your own experience/personal tolerance? Or were you taught this as a general rule of thumb?

 

[rjack321]

I'm interested to know how you came to these specific ENDs at these depths? Is this something you've applied to yourself based on your own experience/personal tolerance? Or were you taught this as a general rule of thumb?

Mostly based on how much thinking I feel like the dive requires. At 80+m I want to be as much of an A+ student as possible. I know I have some (slight but noticeable if you pay attention carefully) slowing of my cognition at 25-30m so I back off from that to the point where I feel that I can cognitively handle almost anything thrown at me with minimal delay or thinking twice, that's about 20m. This is mostly about looking at the consequence of severity of a delay or screw up not what I think I can handle or not. A 5min delay at 85m is +40 mins tacked onto the dive and ruinous on the gas plan.

I have a lot more experience in the 55-65m depth range and can function a little bit more from rote muscle memory. And the consequences of thinking twice or being a bit delayed aren't as severe. (an 5extra mins at 60m is ~10-12mins of extra ascent that my gas plans can handle). Hence I feel like any issues that crop up are manageable with a slightly higher END in the 25-30m range. And the consequences of that slight performance degradation are less severe.

As I get shallower, like 40m, in theory I could get away with no helium at all. In part because I don't feel like I'm that far away from a mostly clear head at those depths in open water. Going up 10-15m is pretty simple. In reality I use a modest mix at 40m because having perceptual narrowing and less memory of the details sort of defeats the purpose of diving to me. So at 40m on OC I am happy to use 25/25 for instance, on CCR I would use 21/35 to stay in line with density guidelines and its cheap enough. In a cave I would definitely back off a 40m END - because I may have to deal with a problem for a long time and having even (eg) 20% reduced performance really magnifies problems when you're an hour from even being able to start your ascent. And ENDs >30m are definitely associated with cave fatalities.

I don't think of myself as tolerant or susceptible to narcosis in any special ways.

 

[Storker]

I have a lot more experience in the 55-65m depth range

Frankly, how much do you remember from those dives (assuming you're doing them on air)?

 

[jadairiii]

If everything is going perfectly, then you can be tripping balls and still have fun, but the question for any diver is how much narcosis is "acceptable" when everything has just turned to ****? How "high" do you want to be?

And as others have said, if you SAC starts going through the roof, CO2 is going to hammer you, and that "acceptable" narcosis level may no longer be "acceptable"

No one has ever said "I wish I had had more beer..." when you are sliding sideways on a wet highway at 80mph and blue lights are in your review mirror. (...funny story....)

 

[rjack321]

Frankly, how much do you remember from those dives (assuming you're doing them on air)?

I don't dive air really ever.

For a 55-65m OC dive I would use 18/45 = END 29m/95ft
55-65m on CCR I would use 10/50 and a setpoint of 1.2 = END 28m/93ft

60m isn't "that deep" to me so I feel ok with a 25-30m END. The consequences of a minor screw up at 80 or 90+m are an order of magnitude higher to me so I back off even shallower. If the water were gin clear and toasty warm yeah maybe an 85m dive with an END of 30m would be ok. But if I am going to the trouble of doing a dive that deep, and already bringing trimix, there's no reason for me to skimp on the helium for that serious of a dive.

 

[Celt]

Where did the idea that if you dive deep on air you can’t remember the dive come from? I have worked at 75m and not only could I remember the dive but give a precise run down of the work I’d done and clear instructions to the next diver going in. Once you’re focused on what’s to be done you do not have memory loss. unless of course if you have a memory problem in the first place.

 

[chillyinCanada]

Where did the idea that if you dive deep on air you can’t remember the dive come from? I have worked at 75m and not only could I remember the dive but give a precise run down of the work I’d done and clear instructions to the next diver going in. Once you’re focused on what’s to be done you do not have memory loss. unless of course if you have a memory problem in the first place.

"Except for occasional amnesia of events at depth, the effects of narcosis are entirely removed on ascent and therefore pose no problem in themselves, even for repeated, chronic or acute exposure.[6][20] "

[20] Hamilton, RW; Kizer, KW (eds) (1985). "Nitrogen Narcosis". 29th Undersea and Hyperbaric Medical Society Workshop. Bethesda, MD: Undersea and Hyperbaric Medical Society (UHMS Publication Number 64WS(NN)4-26-85). Retrieved 2008-12-23.

 

[Celt]

"Except for occasional amnesia of events at depth, the effects of narcosis are entirely removed on ascent and therefore pose no problem in themselves, even for repeated, chronic or acute exposure.[6][20] "

[20] Hamilton, RW; Kizer, KW (eds) (1985). "Nitrogen Narcosis". 29th Undersea and Hyperbaric Medical Society Workshop. Bethesda, MD: Undersea and Hyperbaric Medical Society (UHMS Publication Number 64WS(NN)4-26-85). Retrieved 2008-12-23.

Thank you. Interesting read for tonight when I get home from work.

 

[chillyinCanada]

Thank you. Interesting read for tonight when I get home from work.

Don't forget

 

[Searcaigh]

Don't forget