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Kidder
09-08-2007, 21:42
Hi there, who here has felt nitrogen narcosis. I thick that saftey is always a good thing to talk about. I've been down to around 90 feet and have yet to feel it. I would like to hear from some that have.

dmdoss
09-08-2007, 23:48
Humm, don't remember........

somewhereinla
09-09-2007, 06:05
I have been to 97 feet haven't felt it yet. I am doing another deep dive today I'll see if I feel narc... I hear that sometime you are narc but doesn't realize it...

Splitlip
09-09-2007, 07:27
Two times I was very aware of being narked were a 147 ft dive and a 165 ft chamber ride. I was reminded of the dentist's nitrous oxide.

Zenagirl
09-09-2007, 08:27
It is likely that at 90 and 97 feet there is some kind of narcosis going on, but you might not be aware. When my husband hits 100' or deeper, he starts feeling a drunk-like impairement. I don't get that same feeling, and my first indication of being narc'ed was when I went to 130 feet for the first time (133' actually) and my computer started beeping. It took me a second to realize what the beeping was (slowed response time), and when I looked at the computer I saw the number 3 on the screen (my computer is AI), all I could think was that in 3 minutes I'd run out of air and had to get shallow. I immediately began swimming up and along the wall while watching my computer. At no time did I panic and I did not exceed a safe ascent rate, but I was total focused on getting the number on the computer to go up. When I got to about 80' and my narcosis began to clear, I realized that I had nearly 2200psi in my tank and at how silly I had been to think I only had 3 minutes of air before, when in reality I only had 3 minutes of NDL.

What a huge lesson for me though. Instead of feeling "rapture of the deep" when I'm narc'ed, I get myopic and extremely focused and one-tracked in my thinking. Each time I've gone deep since then, I make sure to work hard at thinking and making sure I don't get one-tracked, AND I figured out that I begin to feel this way at just around 105'.

I think it's important to know how being narc'ed effects you so you won't be caught in an emergency situation while impaired.

ianr33
09-09-2007, 08:51
I have never felt the drunk/incapacitated type of narcosis. Have seen it in others though


when I'm narc'ed, I get myopic and extremely focused and one-tracked in my thinking.
Those are classic narcosis symptoms.Been there myself. I was retrieving a reel at 149 feet.I was quite capable of taking the reel of the tree it was secured to,winding in the slack,locking the reel and clipping it to a D ring,but that was all I could do.My buddys tanks could have exploded and I would have ignored him until I had finished with my reel.
This is the danger of narcosis,you can function at pretty silly depths,but you can't think,so if an emergency does arise you wont react appropriately.

Most commonly I perceive narcosis as a vague paranoia. A feeling that it is dark and spooky and I could die here.Took me a long time to realise that this is actually a physiological response and not a normal reaction to deep dark water.
I get that feeling around 130 in Texas mudholes and a bit deeper,maybe 150 in blue water.

finflippers
09-09-2007, 08:53
I have been to 116' and have not felt any effects of Nitrogen Narcosis yet.

plot
09-09-2007, 10:24
i havn't felt it at 130 yet. but depth doesnt matter, sometimes it hits people at 80 feet that are used to going way deeper... just depends on teh day I guess.

I've heard the first thing you start to hear is drumming in your ears, or tingly in the face... don't know about that though. They say the first thing to go is basic math type skills, so when you can no longer count to 5, you're probably getting narced and need to start ascending.

Kidder
09-09-2007, 10:29
i havn't felt it at 130 yet. but depth doesnt matter, sometimes it hits people at 80 feet that are used to going way deeper... just depends on teh day I guess.

I've heard the first thing you start to hear is drumming in your ears, or tingly in the face... don't know about that though. They say the first thing to go is basic math type skills, so when you can no longer count to 5, you're probably getting narced and need to start ascending.

Sounds like good advice. If you can't count to five you are seriously impaired. I like the post on the confused thinking. misunderstanding alarms etc... It just goes to show that self awareness is a must have skill for deep divers

ScubaToys Larry
09-09-2007, 11:15
When I teach the Nitrox class, we do some comparisons between the symptoms of O2 tox and Nitrogen Narcosis. I always ask if anyone in the class has ever been narc'ed. Normally, I get all no answers... then I go around and ask what the deepest everyone has been... 105, 115, 98, 117 etc.

Then with my most serious look, I pull out my cell phone and say that I need to call the US Navy dive team right away, because according to US Navy tests all the divers have a measurable narcosis effect at 100 feet, so this class must be something special! :smiley32:

Then I point it, it's like asking when was the last time you were drunk? The problem is, you remember (sorta' but try to forget) that party when you were in college and woke up lying on the bathroom stall under a toilet... yup... You were drunk that night.

But if after a few beers, or a few glasses of wine, if someone asked if you were drunk, you'd say no. But if we did some coordination tests, you would probably test out slightly impaired.

And the biggest symptom is a slight euphoria... relaxed.. you just think you've finally mastered your buoyancy and it's a great dive! You don't realize it's a bit of narc hitting you.

Do this test for you and your buddy... It's what I do on advanced classes when I teach... Get a slate and put a math problem down. A simple one like:

2 + 3 - 1 + 5 - 2 - 3 + 4 - 2 + 1 + 4 - 2 = ?

Then make virtually the same question on the other side of the slate.

Pull a stopwatch and do one at 100 feet, the other at the safety stop, and check your results... You might be a bit surprised!

in_cavediver
09-09-2007, 11:19
Having been past 130 on air and on trimix at 200', I personally believe anyone who claims not to have suffered narcosis and has been past 75' or so is deluding themselves. Whether the level of narcosis was serious, debilitating etc is another matter. The simple fact is it exists and anytime you increase the PN2, you start getting narcotic effects.

From my expierience, the most common effect of narcosis is a reduction in cognitive abilities, specifically the higher thought area's. If you don't need to think, you won't notice it. Hence why many people say 'I was at 130' and I wasn't narced'. They were, they just didn't notice it. Its those novel problems which require a thought to solve that cause problems and expose the narcosis.

Now, the money question is what depth does it occur at? Simple question with no clear answer. I've been at 90-100' feeling significant narcotic effects. I've also been at 150' deciding on a deco schedule with much reduced narcotic effects. Different day, different conditions, different dive. I will say this, the 'deep' dive where I clearly had very limited narcosis was a mix dive to 150-160' I still can clearly remember the van wreck, my instructor going OOIG (out of inflater gas, hellava drysuit squeeze) and all of the subtle details. There are several dives in 70-80 range I have done that I can't name those same details.

In the end, narcosis is one more factor divers will have to learn to manage. Some claim acclimatization works, some have a better N2 tolerance, and others swear nothing deeper than 100' without Helium. You, as a diver, will have to make your own determination where the line is for you.

Splitlip
09-09-2007, 11:31
Having been past 130 on air and on trimix at 200', I personally believe anyone who claims not to have suffered narcosis and has been past 75' or so is deluding themselves. Whether the level of narcosis was serious, debilitating etc is another matter. The simple fact is it exists and anytime you increase the PN2, you start getting narcotic effects.

From my expierience, the most common effect of narcosis is a reduction in cognitive abilities, specifically the higher thought area's. If you don't need to think, you won't notice it. Hence why many people say 'I was at 130' and I wasn't narced'. They were, they just didn't notice it. Its those novel problems which require a thought to solve that cause problems and expose the narcosis.


Agree. I probably should have amplified my previous post.
I took an AOW class as a refresher after a break from SCUBA for a number of years.
My deep dive was 97 ft. My instructuror had me do a series of math problems on a slate which I had done a week earlier on the surface. Definitely diminished results.

Kidder
09-09-2007, 11:31
Having been past 130 on air and on trimix at 200', I personally believe anyone who claims not to have suffered narcosis and has been past 75' or so is deluding themselves. Whether the level of narcosis was serious, debilitating etc is another matter. The simple fact is it exists and anytime you increase the PN2, you start getting narcotic effects.

From my expierience, the most common effect of narcosis is a reduction in cognitive abilities, specifically the higher thought area's. If you don't need to think, you won't notice it. Hence why many people say 'I was at 130' and I wasn't narced'. They were, they just didn't notice it. Its those novel problems which require a thought to solve that cause problems and expose the narcosis.

Now, the money question is what depth does it occur at? Simple question with no clear answer. I've been at 90-100' feeling significant narcotic effects. I've also been at 150' deciding on a deco schedule with much reduced narcotic effects. Different day, different conditions, different dive. I will say this, the 'deep' dive where I clearly had very limited narcosis was a mix dive to 150-160' I still can clearly remember the van wreck, my instructor going OOIG (out of inflater gas, hellava drysuit squeeze) and all of the subtle details. There are several dives in 70-80 range I have done that I can't name those same details.

In the end, narcosis is one more factor divers will have to learn to manage. Some claim acclimatization works, some have a better N2 tolerance, and others swear nothing deeper than 100' without Helium. You, as a diver, will have to make your own determination where the line is for you.

Thank you for the info cave diver. As diver we have dangers to deal with all of the time. Nitrogen happens to be a big one. As a rule we can't get complacent and lose the self awareness. I'm thinking a math check at 90 feet (such as multiplication) might be a good idea. Kinda in the same line as checking air and time at depth.

ScubaToys Larry
09-09-2007, 11:34
Hey, maybe like the thing you have to blow into to start your car if you've been convicted of drunk driving to make sure your ok... we could build this into the dive computer!

Every now and then it beeps and pops up a multiple choice question if you're below 60 feet, and if you don't answer correctly, it takes away the rest of your bottom time! :smiley20:

Now I just have to come up with some really, really, easy questions!:smiley36:

plot
09-09-2007, 11:50
maybe we all smoke a LOT of pot so it takes us awhile to get to that "stoned" phase.



...larry should know exactly what i'm talking about ;)

Kidder
09-09-2007, 11:53
Ah clear real world product testing is always a good idea.

crosseyed95
09-09-2007, 14:36
Having been past 130 on air and on trimix at 200', I personally believe anyone who claims not to have suffered narcosis and has been past 75' or so is deluding themselves.

Think this is the 3rd time I've agreed with in_cavediver.. I've been narc'd and I'll admit. In fact, the wife and I talk about it and we know what to look for in each other to know if the other has been hit bad. Been narc'd (bad) at 160' - been narc'd (bad) at 100'. Sometimes it can just depend upon conditions or how bad you suck up the air. However, even when I'm not hit "bad", I know I'm narc'd once I get deeper (75' would be a good number).

To answer the original question very basically: I forget to check my NDL. Therefore, I compensate by checking more often since I know this is my main problem. The wife gets lost in the sense she forgets which way is the rope. Therefore she takes an extra effort to remember. We also have an agreement to abort if either is hit hard enough to question their abilities.

I think accepting it can happen, diving lots, knowing your personal limits (depth) and knowing what you do while narc'd is important. I also believe that being very comfortable with your gear is equally important. Trying to understand a new computer will be twice as hard (if not more) while narc'd.

Side note: one of our group that goes deeper says at 150' it feels like his eyes cross. I've seen him shake is head underwater like he's trying to shake something off.

JCAT
09-09-2007, 16:46
In_cavediver makes a very good post. Spot On!

For me, it's a feeling of fuzzy thinking. I just don't feel as sharp as I should. When that feeling happens, the little voice in my head urges me to stay squared away and concentrate on my situational awareness.

Only way I can explain the fuzzies, as I call them.

ScubaToys Larry
09-09-2007, 17:15
maybe we all smoke a LOT of pot so it takes us awhile to get to that "stoned" phase.



...larry should know exactly what i'm talking about ;)

You know... my avatar looks like that... but I actually never was into that. Probably because I was a musician on the road for 6 years, and all the guys in the band were such idiots when they'd do it, I decided I didn't want to... Much like friends of mine that work in bars that don't drink because they see how drunks act!

WV Diver
09-09-2007, 17:25
Having been past 130 on air and on trimix at 200', I personally believe anyone who claims not to have suffered narcosis and has been past 75' or so is deluding themselves. Whether the level of narcosis was serious, debilitating etc is another matter. The simple fact is it exists and anytime you increase the PN2, you start getting narcotic effects.



I totally agree with this as it is factual and correct. But I guess I must walk around in a daze all the time. I have been below 75 and 100' many times and have not really felt any different. I always look forward to the day when I can experience a good dose of narcosis and pay attention and try to be aware but it never seems any different to me.

Splitlip
09-09-2007, 17:30
maybe we all smoke a LOT of pot so it takes us awhile to get to that "stoned" phase.



...larry should know exactly what i'm talking about ;)

but I actually never was into that. Probably because I was a musician on the road for 6 years,

right...:smiley2:

Splitlip
09-09-2007, 17:38
maybe we all smoke a LOT of pot so it takes us awhile to get to that "stoned" phase.



...larry should know exactly what i'm talking about ;)

but I actually never was into that. Probably because I was a musician on the road for 6 years,

right...:smiley2:

In fairness, I was in college in the 70's. I did not party that way either. I played poker pretty regularly and could count on cleaning out the heads such that I considered it regular income.

Capt Hook
09-09-2007, 18:02
I remember when I did AOW, had to put together a PVC pipe puzzle - took considerably longer at depth than on the boat. And I didn't think I was at all Narced!

Defman
09-09-2007, 18:08
Hi there, who here has felt nitrogen narcosis. I thick that saftey is always a good thing to talk about. I've been down to around 90 feet and have yet to feel it. I would like to hear from some that have.

I agree with what Splitlip said, "noticable" was kinda like being on nitrous oxide. I was at 155' on San Fran Wall in CZM.. took a picture of my computer, popped up 10 feet and it "went away". For those of us who'd never been to 130 we had to do over 130 since we were doing Devil's Throat the next day.

Technically you are always a little narc'ed, it's just whether it's noticable. Like Larry said, do a math problem at the surface and again at depth, you'll see a difference. In the classes we used a combination lock. You may not feel narc'ed, but you are.

Vercingetorix
09-09-2007, 18:15
Most commonly I perceive narcosis as a vague paranoia. A feeling that it is dark and spooky and I could die here.Took me a long time to realise that this is actually a physiological response and not a normal reaction to deep dark water.I just did a deep dive to only 85 feet and that is EXACTLY how I felt. Add to that cold, 50 degree water.

I signalled to my buddy that I was cold and to ascend. Upon hitting about 50 feet, we leveled out. I immediately lost the "dark and spooky feeling", and I signalled that could again go back down.

I've never felt the "rapture of the deep" either. Now that I know that this paranoia is also a narc sign, I can deal with it.

thanks

Splitlip
09-09-2007, 18:21
I remember when I did AOW, had to put together a PVC pipe puzzle

Making a BONG eh?

WV Diver
09-09-2007, 18:21
I remember when I did AOW, had to put together a PVC pipe puzzle

Making a BONG eh?
:smiley20: :smilie39::smilie39: :smiley32:

ScubaToys Larry
09-09-2007, 18:22
Now that I know that this paranoia is also a narc sign, I can deal with it.

thanks

Just because you're paranoid, it doesn't mean someone is not out to get you. :smiley36:

ScubaGir1
09-09-2007, 18:29
During my advanced class the instructor had us use a piece of rope and tie as many knots on it in 20 seconds out of water. So...obviously we did it when we were not narc'ed, and then did it again at 100' to see if we were feeling any different. None of us appeared to be feeling any different. I was just freezing my butt off!!!! But...I'm a chicken for cold water, it was less than 55 degrees :smiley5:

Vercingetorix
09-09-2007, 18:38
Just because you're paranoid, it doesn't mean someone is not out to get you. :smiley36:Everytime I walk into the ScubaToys store, I KNOW that web-cam is looking at me and my cellphone is broadcasting my conversation (thanks to the FBI's open-mike functionality).

TxHockeyGuy
09-09-2007, 19:05
I've felt the effects of narcosis anytime I've gone down to 90 ft. If I'm doing a leisurely reef dive I just feel a little happy so I be sure to check my gauges frequently. I've experienced severe narcosis twice around 90-100' and both times I was finning really hard. I felt like I had been drugged, my breathing rate went through the roof, and I felt like I needed to go up immediately. The one time I had to ascend to 70' get my breathing back under control, the other time I was able to do so without ascending. Just a few more data points for those keeping score.

picxie
09-09-2007, 19:22
I can feel it once I get below about 35m (115 feet).

On my deep dive in my AOW course, we went to 23m (75 feet). The tutor got me to write my name backwards then do a maths calculation. My name was fine ... but I stumbled on the calculation for the simple fact that I couldn't do it. When we surfaced he made a comment that I must have been 'narked as' but the reality was I just couldn't do the calculation!!

dmdoss
09-09-2007, 19:28
Try to open a combination lock at 120ft. See how you do.

Kidder
09-09-2007, 21:51
I've felt the effects of narcosis anytime I've gone down to 90 ft. If I'm doing a leisurely reef dive I just feel a little happy so I be sure to check my gauges frequently. I've experienced severe narcosis twice around 90-100' and both times I was finning really hard. I felt like I had been drugged, my breathing rate went through the roof, and I felt like I needed to go up immediately. The one time I had to ascend to 70' get my breathing back under control, the other time I was able to do so without ascending. Just a few more data points for those keeping score.

The severe Narc sounds pretty scary. Sounds like you were disoriented and in a bad way. It would be hard to keep your head feeling like that.

ianr33
09-09-2007, 22:10
I've experienced severe narcosis twice around 90-100' and both times I was finning really hard. I felt like I had been drugged, my breathing rate went through the roof, and I felt like I needed to go up immediately.

That was probably due to Carbon Dioxide. CO2 is much more narcotic than N2. If it happens again stop swimming and take some deep breaths. Heading up 20 or 30 feet wont hurt either.

JCAT
09-10-2007, 05:19
Try to open a combination lock at 120ft. See how you do.

I have a hard time doing that on the surface!

greyzen
09-10-2007, 08:50
We used a slate that had 1 - 25 printed on it.
Touch 1 - 25 and then 25 - 1.

On the surface, no worries.
At 86' one of the guys with us tended to switch 12 and 21, and hit 13 for 3/etc.

He mentioned that when we got down there, he was finding himself having to actively pay attention.

plot
09-10-2007, 16:37
Try to open a combination lock at 120ft. See how you do.

whats awesome is when they have you do it wearing 7mm gloves

in_cavediver
09-10-2007, 17:06
Having been past 130 on air and on trimix at 200', I personally believe anyone who claims not to have suffered narcosis and has been past 75' or so is deluding themselves. Whether the level of narcosis was serious, debilitating etc is another matter. The simple fact is it exists and anytime you increase the PN2, you start getting narcotic effects.



I totally agree with this as it is factual and correct. But I guess I must walk around in a daze all the time. I have been below 75 and 100' many times and have not really felt any different. I always look forward to the day when I can experience a good dose of narcosis and pay attention and try to be aware but it never seems any different to me.

You know, I don't really feel any different either. At least not until I have to do something different. Its that whole novel concept idea. Until you do it, you don't really understand how hard it is. I learned that when I had to navigate back in a quarry to a wall and had to remember my geography to get there. (took a while)

Now, for a test. Go to a country store somewhere and get one of those brain teaser puzzles for kids. Go to 100' or 80', and solve it. Have your buddy time you. THEN, do it again on the surface. The problem with math problems, combination locks et al is that in some cases, the problems aren't novel. Take a student, he may open a combo lock 4-5 times a day. He'd likely never see the difference. Take an engineer, simple math is simple math. Hell, when I was an undergrad the first time, I took a calc exam after hitting the bars. (got an A too!).

On another note, I didn't mention it but exertion and CO2 retention also seem to enhance narcosis. Other environmental factors such as cold, dark, overheads etc serve to give yet more anxiety which also seems to enhance narcosis.

The most I have ever been narced was at 135' at Gilboa in Feb. Cold, dark and did I say cold (water in the high 30's low 40's). I had the paranoria coupled with disorientation. Got back to 60', was fine.

skdvr
09-10-2007, 17:08
This is a great Thread... I too think (well thought) that I have never been narc'd but after readign all of this I am sure that I have. I think that it was a great way of describing it with the drunk stories. No one thinks they are drunk after 2 or 3 beers but in reality they are. I am going to try doing the math thing on my next dives past 70 ft or so and see how I do.

Great Post Kidder....

Phil

deepdiver47
09-10-2007, 18:28
mine happens at about 90 ft and is quite predictable. I have found that that ascending just a few feet makes it diminish. It is short and really only happens once a dive.

I have found one thing that is interesting. I can make it very predictable given the amount of hydration I give my body. A large amount of water helps to deter it from happening. I will begin to hydrate my body days before I dive as I will usually dive during a biz trip to Asia.

pnevai
09-10-2007, 19:18
Getting narced is natures way of reminding you that you are too #$^# deep!

plot
09-10-2007, 19:26
Getting narced is natures way of reminding you that you are too #$^# deep!

if i didnt wanna go deep, i'd take up snorkeling, it's alot cheaper than diving. :smiley2:

Kidder
09-10-2007, 20:45
Well said Plot!
I was watching the discovery channel and the depths and what industrial divers do at depth is crazy. I imagine nitrogen narcosis is just a way of life for them.

in_cavediver
09-10-2007, 21:10
Well said Plot!
I was watching the discovery channel and the depths and what industrial divers do at depth is crazy. I imagine nitrogen narcosis is just a way of life for them.

No, Helium makes a world of difference. When you dive trimix, you can calculate the END or equivalent narcotic depth. This is just a measure of how narcotic the dive will be scaled as if it was an air dive to a given depth. For instance, a common sport blend is 15/55 or 15% O2 55% Helium and 30% Nitrogen. So, at say 250', the END is 76ft on air. Crazy depth but very reasonable narcotic level. IE, your at 250' but feel like 76'.

This can be repeated for just about any depth to reduce narcosis to a level you choose.

Math for those interested:
Ambient Pressure @ 250 is 8.6ata
PN2 of 15/55 @ 250 is 2.6ata (8.6*0.30)

Now, we have the PN2, lets find what depth that is for air.
PN2 / 0.79 gives the Ambient Pressure = 3.3ata
Convert ata to FSW = (3.3-1)*33 = 76ft

Kidder
09-10-2007, 21:50
Well said Plot!
I was watching the discovery channel and the depths and what industrial divers do at depth is crazy. I imagine nitrogen narcosis is just a way of life for them.

No, Helium makes a world of difference. When you dive trimix, you can calculate the END or equivalent narcotic depth. This is just a measure of how narcotic the dive will be scaled as if it was an air dive to a given depth. For instance, a common sport blend is 15/55 or 15% O2 55% Helium and 30% Nitrogen. So, at say 250', the END is 76ft on air. Crazy depth but very reasonable narcotic level. IE, your at 250' but feel like 76'.

This can be repeated for just about any depth to reduce narcosis to a level you choose.

Math for those interested:
Ambient Pressure @ 250 is 8.6ata
PN2 of 15/55 @ 250 is 2.6ata (8.6*0.30)

Now, we have the PN2, lets find what depth that is for air.
PN2 / 0.79 gives the Ambient Pressure = 3.3ata
Convert ata to FSW = (3.3-1)*33 = 76ft

Are there any adverse effects to diving helium? Take nitrox for example with oxygen toxicity.

skdvr
09-10-2007, 22:15
Well said Plot!
I was watching the discovery channel and the depths and what industrial divers do at depth is crazy. I imagine nitrogen narcosis is just a way of life for them.

No, Helium makes a world of difference. When you dive trimix, you can calculate the END or equivalent narcotic depth. This is just a measure of how narcotic the dive will be scaled as if it was an air dive to a given depth. For instance, a common sport blend is 15/55 or 15% O2 55% Helium and 30% Nitrogen. So, at say 250', the END is 76ft on air. Crazy depth but very reasonable narcotic level. IE, your at 250' but feel like 76'.

This can be repeated for just about any depth to reduce narcosis to a level you choose.

Math for those interested:
Ambient Pressure @ 250 is 8.6ata
PN2 of 15/55 @ 250 is 2.6ata (8.6*0.30)

Now, we have the PN2, lets find what depth that is for air.
PN2 / 0.79 gives the Ambient Pressure = 3.3ata
Convert ata to FSW = (3.3-1)*33 = 76ft


Reading stuff like this makes me want to get in the water a LOT and get into some Tech stuff. I would like to get to the point of diving trimix and doing deep deco. My wife says "NO WAY!!!" but we will see in a few years what will happen...

Thanks for the post...

Phil

tc_rain
09-10-2007, 22:22
125' and didn't notice any narcosis. Wait, I feel it now. Never mind that is just rum.

tc_rain
09-10-2007, 22:24
Math for those interested:
Ambient Pressure @ 250 is 8.6ata
PN2 of 15/55 @ 250 is 2.6ata (8.6*0.30)

Now, we have the PN2, lets find what depth that is for air.
PN2 / 0.79 gives the Ambient Pressure = 3.3ata
Convert ata to FSW = (3.3-1)*33 = 76ft[/QUOTE]

Too much rum, can't follow this right now.

in_cavediver
09-11-2007, 05:18
Well said Plot!
I was watching the discovery channel and the depths and what industrial divers do at depth is crazy. I imagine nitrogen narcosis is just a way of life for them.

No, Helium makes a world of difference. When you dive trimix, you can calculate the END or equivalent narcotic depth. This is just a measure of how narcotic the dive will be scaled as if it was an air dive to a given depth. For instance, a common sport blend is 15/55 or 15% O2 55% Helium and 30% Nitrogen. So, at say 250', the END is 76ft on air. Crazy depth but very reasonable narcotic level. IE, your at 250' but feel like 76'.

This can be repeated for just about any depth to reduce narcosis to a level you choose.

Math for those interested:
Ambient Pressure @ 250 is 8.6ata
PN2 of 15/55 @ 250 is 2.6ata (8.6*0.30)

Now, we have the PN2, lets find what depth that is for air.
PN2 / 0.79 gives the Ambient Pressure = 3.3ata
Convert ata to FSW = (3.3-1)*33 = 76ft

Are there any adverse effects to diving helium? Take nitrox for example with oxygen toxicity.

One of the biggest is that its a light gas and ongasses/offgases very quickly. IE, in the concept of NDL, they are much shorter. (I don't buy into any NDL with mix, IMHO all mix dives should have stops). There's more when you get really deep (400-600+) with High Pressure Nervous Syndrome and Deep Water Blackout but for HPNS, a little N2 helps and for the Deep Water Blackout, CO2 retention becomes an issue.

I guess what I am saying is that depth complicates everything. There is no free lunch and if you want to go deep, then you pay the price. (And He is REALLY expensive, think up to $100-$150 for a gas fill in doubles for a single dive if done commercially)

DennisW
09-11-2007, 07:33
I always get a kick out of people that say they have never been narc'd. Either their instructor didn't give a very good lesson on human physiology or they were asleep during that lesson. If they really haven't been narc'd then they have never been diving. If you have ever dived, you have been under the influence of nitrogen narcosis. You may not know it, but you have been narc'd.

CompuDude
09-11-2007, 15:39
I dunno. I've been on a chamber ride to 165', and did math problems, solved simple puzzles, and screwed and rearranged some nuts n' bolts, etc., and my speeds were comparable to 1 ATA. I was noticably "giggly" but had no problems doing the skills... of course, I wasn't very task loaded. Ditto for test dives (PADI's Deep cert, for instance) at 135'... and those were at least real dives in open water, so there was at least somewhat more task loading going on.

I've been on many dives over 100', and quite a few in the 110-130 range, although the numbers drop off quickly over that.

I've had a noticeable sensation of being narked ONCE. At 115. Hit me like a 5 beer beer bong. I immediately ascended about 20' and it went away as fast as it had come on. I've been deeper before and since, and that was the one time I really felt anything.

Any time I go over 100' I prepare myself for the possibility of narcosis, however, and remind myself to check depth/time/NDL/gas avail frequently, and plan to continue this self-prep, whether or not I'm feeling anything unusual.

Kidder
09-12-2007, 21:21
Well said Plot!
I was watching the discovery channel and the depths and what industrial divers do at depth is crazy. I imagine nitrogen narcosis is just a way of life for them.

No, Helium makes a world of difference. When you dive trimix, you can calculate the END or equivalent narcotic depth. This is just a measure of how narcotic the dive will be scaled as if it was an air dive to a given depth. For instance, a common sport blend is 15/55 or 15% O2 55% Helium and 30% Nitrogen. So, at say 250', the END is 76ft on air. Crazy depth but very reasonable narcotic level. IE, your at 250' but feel like 76'.

This can be repeated for just about any depth to reduce narcosis to a level you choose.

Math for those interested:
Ambient Pressure @ 250 is 8.6ata
PN2 of 15/55 @ 250 is 2.6ata (8.6*0.30)

Now, we have the PN2, lets find what depth that is for air.
PN2 / 0.79 gives the Ambient Pressure = 3.3ata
Convert ata to FSW = (3.3-1)*33 = 76ft

Are there any adverse effects to diving helium? Take nitrox for example with oxygen toxicity.

One of the biggest is that its a light gas and ongasses/offgases very quickly. IE, in the concept of NDL, they are much shorter. (I don't buy into any NDL with mix, IMHO all mix dives should have stops). There's more when you get really deep (400-600+) with High Pressure Nervous Syndrome and Deep Water Blackout but for HPNS, a little N2 helps and for the Deep Water Blackout, CO2 retention becomes an issue.

I guess what I am saying is that depth complicates everything. There is no free lunch and if you want to go deep, then you pay the price. (And He is REALLY expensive, think up to $100-$150 for a gas fill in doubles for a single dive if done commercially)

I looked this up. Apparantly another drawback to Helium is that it steals body heat. For those of you that are curious here is a link on high pressure nervous syndrome http://scuba-doc.com/HPNS.html.

BobbyWombat
09-27-2007, 15:00
I've done one dive that was 85 ft. I didn't FEEL impaired at all, but I do remember that I was hearing a "buzzing" sound. Might this be akin to the "ringing" some people have reported?

I honestly couldn't tell if it was actually something making this noise (like a distant boat) or a physiological response to depth.

Cojrock
09-27-2007, 19:35
Ive only ever been really narked once, it was nothing compared to being a bit narked. I was at about 64m. It kinda felt like a mix of E and Nitrosoxide (laughing gas). All it took was some inner-focus to make it not a deal at all. Maybe all the practice i get at mind altered states helps for being smashed at depth?! I dont plan on going to that depth again on air but who knows, its my life to risk.

Kidder
09-27-2007, 20:43
Ive only ever been really narked once, it was nothing compared to being a bit narked. I was at about 64m. It kinda felt like a mix of E and Nitrosoxide (laughing gas). All it took was some inner-focus to make it not a deal at all. Maybe all the practice i get at mind altered states helps for being smashed at depth?! I dont plan on going to that depth again on air but who knows, its my life to risk.

How deep were you?

CompuDude
09-27-2007, 20:49
Ive only ever been really narked once, it was nothing compared to being a bit narked. I was at about 64m. It kinda felt like a mix of E and Nitrosoxide (laughing gas). All it took was some inner-focus to make it not a deal at all. Maybe all the practice i get at mind altered states helps for being smashed at depth?! I dont plan on going to that depth again on air but who knows, its my life to risk.

How deep were you?

64m = ~ 210 feet.

ianr33
09-27-2007, 22:52
Ive only ever been really narked once, it was nothing compared to being a bit narked. I was at about 64m. It kinda felt like a mix of E and Nitrosoxide (laughing gas). All it took was some inner-focus to make it not a deal at all. Maybe all the practice i get at mind altered states helps for being smashed at depth?! I dont plan on going to that depth again on air but who knows, its my life to risk.

How deep were you?

64m = ~ 210 feet.

Dont have a huge amount of sympathy for that :smiley36:

datamunk
10-01-2007, 22:31
i think rule of thumb is around 120 feet, for most people. i was doing a dive in jupiter called Hole in the Wall, thats i believe around 140? anyway, around 110 i was nar'q completely, andw asnt very happy about it. i went thru the hole in the wall (big swim thru), read a plaque on the wall to be asked what it said later, and once thru raised up about 30 feet to get rid of the affects. also, once i got thru there were 2 or 3 bullsharks circling the entrance! great spot for spearfishin

anyway, it was my first and last time, and i didnt really enjoy it but i knew it was comin, could be wild if you had no idea.

just dont go deep unless you are experienced, i had the experience of depth, just not THAT deep, but yea... definately interesting.

sidneydiver
10-01-2007, 22:44
I was narked while doing some deep dives for tec training. I generally had a feeling of complacency and almost felt a little bored or depressed which was not pleasant at all. My buddy and I both noticed that we checked on each other less. My other weird feeling was that my feet felt like jelly, like they didn't really belong to me which wasn't altogether unpleasant!

wgt
10-03-2007, 09:57
Many of the disagreements concerning the nature of nitrogen narcosis reflect differences in the definition of the phenomenon. For some, nitrogen narcosis is only present when they notice (are aware of) changes in cognition, motor skills, or sensory experience (e.g., "I feel funny," "time seemed to pass more slowly," "I felt clumsy with my hands"...). Others (commonly instructors) tend to define it as a verifiable change in performance (e.g., taking longer to solve the equation, getting the answer to the riddle wrong, etc.).

However the phenomenon is operationalized, it reflects a disturbance in nervous function stemming from pressure-dependent increases in the solubility of nitrogen in fats (good inhalable anesthetics tend to dissolve very well in fats but relatively poorly in water). Under pressure, the nitrogen accumulates in the fat-rich membranes of the cells of the body, including those of the nervous system. When this happens, the membranes become permeable to ions and water, which contributes to nervous dysfunction.

This process begins the moment that the pressure increases. Thus, whether at 2 meters or 50 meters, the air-breathing diver begins to accumulate nitrogen in the cellular membranes, and the cells change functionally. This only becomes an issue, however, when the diver either recognizes through introspection that he/she is intoxicated ("I feel different") or when the performance of the nervous system can be demonstrated objectively to have declined ("it took me longer to...").

As for helium, it tends to exert the opposite effects on the nervous system, making cellular membranes less permeable to ions and water. This explains why, as noted by another poster, nitrogen and helium can be used to offset some of each other's less desirable effects.

shadragon
10-03-2007, 12:23
You know... my avatar looks like that... but I actually never was into that. Probably because I was a musician on the road for 6 years, and all the guys in the band were such idiots when they'd do it, I decided I didn't want to... Much like friends of mine that work in bars that don't drink because they see how drunks act!
I watched so many guys in the service drink their paychecks away it was scary. Get paid Friday, drink your face off and be borrowing $20 off me on Sunday.

dutchman
10-03-2007, 17:21
"Slight euphoria... relaxed.. you just think you've finally mastered your buoyancy and it's a great dive!" I get that every time I blow bubbles.
I have only been to 91 feet (FSW).

RevDoc
10-03-2007, 20:17
I have a question for those of you who know. Does narcosis literally not set in at all above say 60', or is the effect just negligable? In other words, could one person experience significant narcosis much shallower than the depth your are discussing, or is that just physiologically not an issue?

Kidder
10-03-2007, 21:26
Many of the disagreements concerning the nature of nitrogen narcosis reflect differences in the definition of the phenomenon. For some, nitrogen narcosis is only present when they notice (are aware of) changes in cognition, motor skills, or sensory experience (e.g., "I feel funny," "time seemed to pass more slowly," "I felt clumsy with my hands"...). Others (commonly instructors) tend to define it as a verifiable change in performance (e.g., taking longer to solve the equation, getting the answer to the riddle wrong, etc.).

However the phenomenon is operationalized, it reflects a disturbance in nervous function stemming from pressure-dependent increases in the solubility of nitrogen in fats (good inhalable anesthetics tend to dissolve very well in fats but relatively poorly in water). Under pressure, the nitrogen accumulates in the fat-rich membranes of the cells of the body, including those of the nervous system. When this happens, the membranes become permeable to ions and water, which contributes to nervous dysfunction.

This process begins the moment that the pressure increases. Thus, whether at 2 meters or 50 meters, the air-breathing diver begins to accumulate nitrogen in the cellular membranes, and the cells change functionally. This only becomes an issue, however, when the diver either recognizes through introspection that he/she is intoxicated ("I feel different") or when the performance of the nervous system can be demonstrated objectively to have declined ("it took me longer to...").

As for helium, it tends to exert the opposite effects on the nervous system, making cellular membranes less permeable to ions and water. This explains why, as noted by another poster, nitrogen and helium can be used to offset some of each other's less desirable effects.

Wow thank you for the detailed description. Very informative. I've never heard it spelled out so explicitly.

CompuDude
10-04-2007, 12:17
I have a question for those of you who know. Does narcosis literally not set in at all above say 60', or is the effect just negligable? In other words, could one person experience significant narcosis much shallower than the depth your are discussing, or is that just physiologically not an issue?

As wgt's post points out, technically it starts almost immediately. For the vast majority of divers, it doesn't start getting severe enough to actually impair you in any meaningful way until start approaching 4 ATA (~100'). Beyond that, the majority of divers can detect at least some effect, but it varies from person to person and even day to day.

I know a small handful of divers who are somewhat uncomfortable with their level of impairment over 80'. I know others who have rarely been noticeably impaired even on multiple dives to 120' (myself included). But the physiological effect is there no matter what, how well you compensate for it is going to vary from person to person... and again, the same person can be affected more on one dive than another, for no readily apparent reason.

BobArnold8265
10-05-2007, 10:40
I'm afraid that I'm another one who hasn't felt (or didn't realize it when I did) narcosis. I've been diving for 5 years now and have had many dives in the 100 to 130 foot range and have never felt any different. Next time I'm down that deep, I'll have to try Larry's math check !!!