i think lynne is right.

[boulderjohn]

No more 100 foot cave dives on Nitrox for this gal, not ANYWHERE!

The time in my life when I was most obviously narced because of stupidity was also at 100 feet, inside a wreck in Chuuk. I watched our guide go through a hole in a bulkhead, with a piece of pipe sticking down from the upper right corner. I thought, "It would be easy to catch the regulator hose on that. Better be careful." (I was still diving a conventional hose setup then.) My buddy went through next, and he caught his regulator hose on it. He pulled it down and continued through. I then went through and caught my regulator hose on it. I asked myself two questions: 1) Which hose have I caught? 2) Do I pull it up or down to free it? Then I realized how stupid those questions were, and realized I must be narced.

That is why I take no comfort in people saying that I will be able to perform all sorts of mental feats accurately if I keep my END to 100 feet.

 

[LiteHedded]

trimix is just good stuff. makes stages more manageable and dives more enjoyable.

 

[BabyDuck]

john, nothing earth-shattering. i just realized that almost all the times i'd not been able to figure my buddy out, or forgot the next bit to the plan, or was watching someone's hands flapping about without trying to decipher what they were trying to communicate were at ginnie. i guess i thought narcosis was the 'big stupid' (and maybe it would be for me, at some deeper depth), but didn't recognize it as lots of forgivable, forgettable, mini-stupids. part of that might be because i have lots more cave experience than deeper ocean experience. sorta like other john said, anything like that that happens on ocean dives i put to being more of a newbie there - but maybe that's not it. and when i see the difference in how i respond in different caves, a light bulb just came on.

i guess the big change of idea for me, really, is that narcosis doesn't look or feel how i thought it would.

 

[DA Aquamaster]

Marci is by far the best cave diving team mate I have ever had - we know each other well and are very compatible together as a team, so in no way do I want this to sound like a negative, because it is not and the light bulb going on just makes her even stronger as a team mate.

However a light bulb moment for me was realizing, particularly after doing more side mount diving in some deeper, siltier and more confined areas is that Marci gets very cheerful at higher ENDs - and she gets downright fearless. That struck me as not always being a good thing in a cave environment, especially in tight and silty areas at higher ENDs where a healthy dose of prudence is a good thing.

---

A light bulb for my diving/performance has been noticing how much broader my focus is in a cave on trimix than it is on air. Regardless of whether I am still doing all the required navigation, gear and dive related functions at an acceptable level on nitrox, a little helium in the mix is just a general performance and SA booster.

 

[BabyDuck]

eh, prudence, schmudence. thank you to my buddy for letting me connect these dots myself. even though i think you were just chicken for not wanting to see where that line went that time.

 

[Chris Brown Tech]

Narcosis at high flow caves versus low flow (and wrecks too!) in shallow depths is real. Its caused in some part by the narcotic effect of CO2, which adds to that already caused by the nitrogen. I can relate to people noticing it more at Ginnie than at Little River.

If you also consider 02 to be narcotic, then you are in effect, breathing a narcotic gas whichever way you look at it. So the martini effect is real at around 100' Adding helium is just like diluting the martini with a non-alcoholic mixer

 

[DA Aquamaster]

Narcosis at high flow caves versus low flow (and wrecks too!) in shallow depths is real. Its caused in some part by the narcotic effect of CO2, which adds to that already caused by the nitrogen. I can relate to people noticing it more at Ginnie than at Little River.

If you also consider 02 to be narcotic, then you are in effect, breathing a narcotic gas whichever way you look at it. So the martini effect is real at around 100' Adding helium is just like diluting the martini with a non-alcoholic mixer

The irony here is that when people are deeper, working harder, or worse, start to see a problem developing that may push their gas reserve to uncomfortable levels, they start worrying more about gas usage. Consequently, when they most need a clear head, they will attempt to stretch the gas by lowering their respiration rate to artificially low levels to reduce gas consumption. However they fail to consider that while there is lots of excess O2 in each breath that makes the practice appear plausible, CO2 levels are determined by 1) how much O2 your body is using (more work = more O2 used = more CO2 produced) and 2) your respiration rate (as in how often you exhale).

Consequently, trying to lower your SAC effectively increases CO2 levles and in turn narcosis, which creates what amounts to an artificially deep END on any given gas regardless of whether it is air, nitrox or trimix. When I encounter a normal sized male diver who claims a real world SAC of .4 or less on the working portion of the dive, I pretty much plan on them being dumb as a post in the water if the END is anywhere below 80'-90'.

Personally, I bring along enough gas, worry a lot less about SAC and a lot more about proper ventilation to remove CO2 efficiently when the workload goes up.

 

[ucfdiver]

I can't tell the difference scootering Ginnie on 21/35 vs 32%...never planned a 30/30 dive there, always used a leftover stage that happened to have mix in it. On the one planned trimix dive I did there in the back, I could most certainly tell the difference when switching to trimix from our travel nitrox stages, since we were swimming.

For photography/video dives especially, I'll use 30/30 there from now on. I got a pounding co2 headache trying to hold position in flow last time.

 

[Slamfire]

nevermind.

 

[gsk3]

I can't tell the difference scootering Ginnie on 21/35 vs 32%.

I wonder how much of the effect is CO2 due to increased WOB. That would explain no difference while scootering but a difference while kicking....