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Old 09-11-2007, 07:33 AM   #51
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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.


"Suppose you were an idiot ... And suppose you were a member of Congress ... But I repeat myself."
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Old 09-11-2007, 03:39 PM   #52
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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.
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Old 09-12-2007, 09:21 PM   #53

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Originally Posted by in_cavediver View Post
Originally Posted by Kidder View Post
Originally Posted by in_cavediver View Post
Originally Posted by Kidder View Post
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
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Old 09-27-2007, 03:00 PM   #54
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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.
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Old 09-27-2007, 07:35 PM   #55

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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.
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