What is the Shallowest Depth at which You Notice Narcosis?

[Laurie S.]

I was given the math test my first time past 100 feet to see if I was affected. I was at 103 feet and I did the test faster than I had done it on the boat. My instructor said he had never seen that happen before and he has been teaching for almost 40 years. He tried me again later and it happened again. Now he wants to try me on a combination lock to see what happens. He's a research psychologist and gave me some insights into how the brain functions with regards to narcosis. He said it will hit younger people at shallower depths because until you're into your mid-20s, the brain synapses aren't completely established. People who start diving at more mature ages will have a more mild reaction because their brain is able to handle it.

He had a student one time who tried to make love to a rock at about 60 feet. He didn't remember any of it later.

 

[James R]

He had a student one time who tried to make love to a rock at about 60 feet. He didn't remember any of it later.

Shenanigans, me thinks...I am not saying I don't believe you, but I don't believe your student. IMO Narcosis at 60' is not going to cause that behavior and even less likely to cause short-term memory loss.

 

[Drin]

Shenanigans, me thinks...I am not saying I don't believe you, but I don't believe Narcosis at 60' is going to cause that behavior and even less likely to cause short-term memory loss.

Agreed.

-Adrian

 

[Soakedlontra]

Cold also have a direct impact on narcosis. My instructor years ago took me on a quick intro to twins in the middle of winter. Water temp was below 10 Celcius (50f) and he could not perform a basic valve drill at the 30ft platform. He was in 5mm wetsuit and no hoodie.

I am still not sure if it was narcosis or brain-feeeze.

This makes me wonder about your instructor...

 

[Laurie S.]

Shenanigans, me thinks...I am not saying I don't believe you, but I don't believe your student. IMO Narcosis at 60' is not going to cause that behavior and even less likely to cause short-term memory loss.

Wasn't my student, and it did happen.

 

[James R]

Wasn't my student, and it did happen.

I am sure it happened, but experience (and student bs meter) tells me he was well aware of it and still remembers doing it.

 

[tracydr]

I can feel it at 125-150. However, I'm definitely narced at 100-110. It's much more obvious to me on colder dives.
I hate the feeling I get when I can actually "feel" it. It is not a pleasant feeling for me. I get a loud, roaring in my ears and an impending feeling of doom.
I did have vertigo once on a really cold dive at about 125 feet but I think my hood was too loose, letting cold water into my ears. However, the vertigo cleared when I was at around 50 feet so it could have been narcosis.
I dislike the feeling enough, and we do enough deeper dives, that I've decided to get trimix trained, even for those 120 foot dives, although I know I'm probably okay on open water dives to this depth.

 

[nolatom]

not at 130, that I could say for sure. Definitely at 140, I headed back up 20-30' and it cleared up.

this on Nitrox 26 or 28 as I recall

 

[tracydr]

What temp did he normally dive in? We dive in the Puget Sound in the winter in temps closer to 40 with no appreciable brain freeze, and 30ft is awfully shallow for that level of narcosis regardless of the water temp.

-Adrian

With a 5ml and no hood? I used a 14 ml farmer john and thick hood/gloves when I was diving wet in PS.

 

[Jack Hammer]

I find it interesting that many people say they only notice it at deeper depths. I've handled complex tasks at 150' on air and successfully done math/ tied knots at 130' without issue. However, I first become aware of a ever so slight decrease in the crispness of my thoughts as shallow as 30' and begin to notice the onset of subtle signs of decreased coordination around 60', especially in cold waters. Judging by how I frequently see other divers in similar depths/conditions behaving, I seriously doubt I am the only one affected by it.


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