What is the Shallowest Depth at which You Notice Narcosis?

[Rhone Man]

It varies heavily from person to person. People often don't have a terribly good sense of their own impairment until they have done some kind of task loading.

I used to say that I didn't feel narcosis until about 140 odd feet, but once when I was diving in Europe I had to convert my remaining gas in PSI to Bar using mental arithmetic. At the surface I have no problem, but I really, really struggled with it at 120 feet.

At 190 feet I have done things that I later had absolutely no recollection of.

When highly experienced tec divers like Gary Gentile and Brett Gilliam say that they are virtually fully functional at 250 feet on air, I believe them. I have seen air force pilots who can do 10 shots of tequila and then still fly a fighter jet (well, in a simulator...), so I have no problem believing that people's physical and mental dexterity varies as much with impairment as without.

 

[Scubagolf]

I have never "noticed" any affect of narcosis in about 20 dives to 100+, including 132' last month to Devil's Throat in Cozumel. However, I have not yet encountered any tasking problems of any significance.

 

[bracko]

Agree with Rhone Man completely.

for me it's hard, I have only really ever felt it at +40m (+130') but taking advanced courses down to 30m 100' and watching them is sometimes absolutely halarious and scary that they don't follow direction and are so slow to react when we give them a non scriped numeric skill to do down at the bottom.

 

[supergaijin]

When I stopped drinking I felt the effects of narcosis more easily. Depending on what I am doing and who I'm with, I'll feel a slight narc at around 3.5ata.

In the last couple of years and after practicing a lot of u/w photography (in Manual) in around 20' of water, I noticed a big difference in how fast I could change between settings. In the shallows I my be at f.2 for a nudibranch, look up and see something larger swimming buy and be able to change settings as I swam without looking at the housing and just relying on 'feel'.

When I began to descend to 3ata, I would need a lot longer to set up shots. Concentration is much more of an effort.

But now that I'm back in NZ drinking my Dad's homebrew, everything is back in focus again

 

[Peter69_56]

When I stopped drinking I felt the effects of narcosis more easily. Depending on what I am doing and who I'm with, I'll feel a slight narc at around 3.5ata.

In the last couple of years and after practicing a lot of u/w photography (in Manual) in around 20' of water, I noticed a big difference in how fast I could change between settings. In the shallows I my be at f.2 for a nudibranch, look up and see something larger swimming buy and be able to change settings as I swam without looking at the housing and just relying on 'feel'.

When I began to descend to 3ata, I would need a lot longer to set up shots. Concentration is much more of an effort.

But now that I'm back in NZ drinking my Dad's homebrew, everything is back in focus again

And that I suspect has a big influence on a persons ability to feel a difference. I drink regularly although not very often to a point these days where I am totally wacked out (maybe once or twice a year if lucky). So maybe if one drinks regularly maybe 4-5 times a week then there is a subtle effect we get used to and we don't realise it. Then if we go diving, as being narced is similar to this effect, we just don't notice it. My wife gets affected significantly but does not drink hardly ever.

SO this brings up a new point perhaps;

Of all those people who have not really felt the effect of being narced, how many are regular drinkers/non drinkers?

Of those who do notice a significant change, how many are not drinkers, or only drink on the odd occasion?

 

[Locus]

And that I suspect has a big influence on a persons ability to feel a difference. I drink regularly although not very often to a point these days where I am totally wacked out (maybe once or twice a year if lucky). So maybe if one drinks regularly maybe 4-5 times a week then there is a subtle effect we get used to and we don't realise it. Then if we go diving, as being narced is similar to this effect, we just don't notice it. My wife gets affected significantly but does not drink hardly ever.

SO this brings up a new point perhaps;

Of all those people who have not really felt the effect of being narced, how many are regular drinkers/non drinkers?

Of those who do notice a significant change, how many are not drinkers, or only drink on the odd occasion?

An interesting tangent.

At 90', I have a subtle sense that something is amiss. It's difficult to describe because I have not yet felt it severely, but I would agree with others' characterizations of it as a slight dulling of thought and/or narrowing of attention.

Aside from the odd bender, I don't drink to excess on a regular basis anymore, but I'll have a glass or two and my tolerance is alright, though as a matter of personal policy I would never drive after more than one drink.

In my experience, staying functional under the influence involves keeping aware of changes in my state of mind, and recognizing them as being products of external causes. As much as is possible, this keeps them out of the way so that function can be maintained. Failing that, an awareness of intoxication should at least be valued as a reminder to use extra caution.

 

[DCBC]

...What is the shallowest depth at which you thought narcosis may have been creeping up on you?

When I was with the Navy at DCIEM, we tested the effects of narcosis in great detail. Chamber dives were made both dry and wet, at different temperatures, with various workloads.

There is quite a variance in how narcosis affects me on different days. I know that its effects start to show themselves at around 50 FSW (regardless if the diver realizes it or not). So I'm aware that my performance is inhibited after this depth. The question becomes not whether narcosis is happening (it is after 50 FSW), but rather how much exposure is too much for safety purposes.

To answer this question, we have to examine risk. One diver may elect to dive in a shallow cave or wreck, another a deep cave or wreck, yet another forgo either because of the increased risk involved. How much risk is present is often determined by the diving conditions, equipment available, fitness, training and the experience of the diver. As these conditions are improved, the risk is lowered.

Generally speaking, I feel comfortable in diving air above 200 FSW. I'll use it to 250 FSW in a pinch, but prefer mix below 150 FSW. This wasn't always the case. I remember getting pretty narced in 120 FSW when I was a teenager.

Personally, I would not be safe driving a car at 200 mph, but other drivers like Sebastian Vettel (the current Formula 1 Champion) make their living doing exactly this (Antonio Pizzonia has recorded a top speed of 230 mph). How is this possible? Years of experience and the personal acceptance of higher risk.

Before people start throwing stones, I'm not advocating diving deeper than one's training, experience and good judgement dictates (nor suggesting people to drive fast on a public roadway).

The fact is that when you dive deeper than 50 FSW on air your risk increases. Your level of safety can only be determined by you and no one else.

There are a number of hypocrites who will chastise those using deep-air, but they can really only speak to the depth they personally feel comfortable at and the risk factors that are acceptable to them...

Training and experience are key factors in any aspect of diving. A good diver must constantly assess what is and is not acceptable and be prepared to thumb a dive if things don't feel right.

 

[diverkun]

Whenever it rains.......

 

[Lorenzoid]

. . .

SO this brings up a new point perhaps;

Of all those people who have not really felt the effect of being narced, how many are regular drinkers/non drinkers?

Of those who do notice a significant change, how many are not drinkers, or only drink on the odd occasion?

I'd even back up a step from this question and ask, as I suggested in an earlier post:

Of all those people who have not really felt the effect of being narced, how many dive regularly?

Of those who do notice a significant change, how many only dive infrequently?

I'm what you'd call a vacation diver--maybe 30-35 dives in a good year--and on most dives, especially nearer the beginning of a trip, I sense something that I THINK is likely narcosis beginning relatively shallow and becoming more distinct with increasing depth. As I pass 80+ feet I'm fairly certain that that increasingly noticeable sensation is narcosis.

 

[shoredivr]

I don't drink alcohol.

My perception of narcosis varies. There is a wreck here in Tobermory On that starts at 65 ft and goes down an incline to 155'. Done that dive dozens of times. If at the beginning of the charter season in May I have been diving below 120 then the narc is less noticeable. If I have not done any dives below 120 the narc at the stern is more noticeable. Of course all this changes with helium.