Trying to figure something out

[String]

Just did our deep dive for AOW cert. I was really wanting to see where my limit is, but was disappointed when I felt nothing when we hit the sand at 116ft.

First of all if its PADI the instructor broke standards. Should be reported.

Allowing playing with a camera on what is meant to be a course dive is silly as well - did the instructor not bother planning enough of a lesson to fill the entire dive or was he just lazy and go down to depth to tick a box?

I seriously doubt a chamber will do anything either - its a totally different root cause and mechanism. Also as stated above the type of test you were doing is often useless in establishing narcosis effects.

Does anyone know the physical factors that affect narcosis ?

Not seen any evidence to suggest thats the case. Factors like tiredness, dehydration and so on do have an effect but body mass and so on ive never seen anything hinting at a link.

 

[PuyallupCoug]

You are narc'd every time you dive and at any depth. It's a matter of how much nitrogen narcosis affects your body based on depth and your personal physiology. Some people feel extremely loopy at 50feet, other people feel nothing at 100 feet. Just remember though that your body undergoes the effects of nitrogen narcosis every time you dive.

 

[Rhone Man]

You are narc'd every time you dive and at any depth.

I don't want to sound like a troll, but I always find statements like that unhelpful. It is the same as saying: "even a few sips of beer affect you." It may be medically true, but in both cases we are talking about such a negligible level of impairment that it is a pedantic rather than a practical point. Relatively few people report suffering any noticeable impairment above 90 feet. Many divers do not feel that they suffer significant impairment until 130 feet. Of course all such reports are subjective, and people are notoriously bad at judging their own impairment (exhibit 1: drunk drivers). Objective measurement is hard. But I still just t think that the everyone-gets-some-impairment-even-at-20-feet story just does not really assist the debate much.

 

[bottomfeeder22]

I got narced last time I dove the Grove - saw the flag flying(?) off in the distance and felt REALLY patriotic, then wanted to fin over to it, even though I knew I didn't have enough gas. For those that don't have a "dark narc", it's more difficult to tell, I'd guess, as there's no panic, just care-free euphoria...... equally if not MORE dangerous than panicking (that may be for another thread).

I also tend to forget chunks of my dive as well, which really sucks, as a landlubber like me doesn't get to dive as often as he'd like (48-49 dives in 5 years - sheesh) due to geographical restraints.

 

[String]

Relatively few people report suffering any noticeable impairment above 90 feet.

Really?

As soon as you stick your head underwater you are going to be impaired. That impairment increases as depth increases.

Other than that narcosis is so variable from person to person and even from day to day you cant say a lot more.

 

[kathydee]

Other than that narcosis is so variable from person to person and even from day to day you cant say a lot more.

Trying to find a pattern of variables that contribute to the obvious sensation of narc impairment might be an interesting SB poll?

 

[TMHeimer]

During the Deep Diver course we were at 130 feet. Can't say that I felt any different. I was concentrating on sticking with my instructor buddy and on the bottom collecting shells for that 10 minutes. That was in 35 degree N. Atlantic water in a 7 mil wetsuit in late May. On other deep dives, I can't say that I have ever felt different. I did the combination lock thing 1 second faster at depth during the AOW class. So who knows. I was probably affected a little and unaware.

 

[jwalko]

I remember one indecent of dark narcosis...not fun.

We were diving in a quarry to about 95'. There was something that one of my dive buddies wanted to show me. This was an unusual day in that the horizontal visibility was pretty decent...40' or more, but the vertical visibility was relatively poor due to layers if silt in the water. So, at 90', it was dark, even though it was a sunny day.

What I remember is being really, really paranoid. I know that I had plenty of gas, but kept checking my spg just to make sure. It was dark and all I could think about was checking my gauge. On the way back, we made our way to about 70' and all I remember is a tremendous sense of relief. I was never so happy to get back to 70'.

It was strange and not a pleasant feeling at all. I don't care to have that feeling again. Oh and we were diving air with water temps at about 40 degrees. Not sure if it was the temperature or the darkness, or both.

I also remember being at 80' in the ocean and feeling great. Just goes to show that, as many have said on this thread, narcosis affects different people differently and the same people differently at different times.

John

 

[flareless]

Interesting thread and one I feel I'm able to comment on. I did my Tec Deep Diving course this summer. During the course my instructor did a couple of things to see how I reacted to narcosis. On one dive he took me down the anchor line to 90 feet FAST. I kept right up behind him then we did our dive. When we surfaced he asked how I was. I told him fine. A guy who was also on the dive was going on and on about how messed up he was at the bottom. He came down the line at a slow pace. It was after the dive that my instructor told me he tried to get me narc'd.

A few more dives into the course had me at the 140 - 150 range. These dives were in the cooler waters of the St. Lawrence river. I felt absolutely no negative narcotic effects on those dives and thoroughly enjoyed the thrill of being at that depth (probably due to narcosis - the good kind).

Later in the season we were attempting a deep wreck dive. I was a bit nervous about this dive but not too worried. That changed once we hit the current at the beginning of the dive. We swam hard to the rim of a wall and hung on tight at the team assembled. When we went over the wall there was a down current that pushed us from 40 feet to 180 feet in just over a minute.

So NOW I'm Narc'd. That's Narc'd with a capital "N". Tunnel vision set in and my mask began to leak due to a problem exacerbated by the extreme pressure. I knew I had no business being in such a dark and cold place. Especially a place without air. There was actually nothing wrong with me, my gear (except for the leaky mask) or my supply of gasses. I just knew that I really wanted to leave. I looked at my instructor, made a circle with my left thumb and forefinger, stuck my right forefinger through the circle then pointed to myself. He took me by the arm and we made our way slowly back to the surface. As we ascended the feeling of "wrongness" at being underwater subsided. That evening was a reflective one. I can tell you I felt like crap at the reaction I had but in retrospect I needed it. The next day we did more Tec drills within the 130 foot range and the following day we did a 30 minute drift dive at 175 feet. I didn't feel narc'd on either of those dives.

I think a lot of what's been said is true and yet there's no way to really nail down narcosis. The narcotic effect of breathing compressed nitrogen happens on every dive yet, like alcohol, it affects people differently. Fitness, hydration, temperature, exercise, stress all affect narcosis but these all depend on the physiology of the diver. Sometimes narcosis is scary but sometimes it makes the dive exhilarating.

During my last dive of the season we were drifting for about 20 minutes at 155 feet. I was feeling a bit narcy and thought "ok, I'll unclip my SPG, shine my light on it, take a reading then clip it back. Keep my self busy in other words. Suddenly the channel narrowed and my teammate and I were shot forward like bullets from a gun. We looked at each other and each of our eyes said the same thing; YEEEEEHAAAWWW!!! That's when having a bit of a narc-on can really make the dive fun.

Still, this year's goal for me is Trimix!

 

[lamont]

As others have said, the excercises given to trainees at depth aren't necessarilly a good indicator. When I was certified I was given long addition, problem was I solved it faster at 100' than at the surface. An instructor friend gives all his students 2 problems one spacial (puzzle), one mental (arithmetic) and tells me that in his experience some students have problems with both at depth, some one but not the other, and some neither. So much for the test.

I noticed that the first thing to really go with narcosis is converting short term memory to long term memory at around 70-80 fsw. The problem with a lot of the "narcosis tests" that OW instructors do at 90 fsw is that they do it first above ground and then test it at depth, which means that you've already set down long-term memories of what the problem is and what the answer is.

A better and simpler test is to simply look once at your SPG then put it away and try to remember what your pressure was even a few seconds later. At 90-100 feet it becomes much more difficult to recall. This often leads to new divers constantly checking their SPG at depth.

I typically don't feel "high" or "impaired" at this point, but if I pay close attention, I'm definitely narc'd. I also often start to daydream when I'm getting narc'd. Usually deeper breathing patterns to clear CO2 helps clear up the daydreams.

I think the problem with people not recognizing narcosis at 90-100 feet is that most people aren't introspective enough to notice subtle symptoms.