200' on air for 5 min bottom time?

[DCBC]

I agree Dale; especially if you consider that the affects of Inert Gas Narcosis (IGN) are not limited to Nitrogen... CO2 is approximately four times more narcotic than N2 and capable of depressing awareness to unconsciousness. Some believe that a high PPO2 also presents similar problems. The truth is, no one knows for certain the mechanisms involved. Dealing with the unexpected while diving, is part of the process. Personally, I'm glad that I've been able to learn how to cope with IGN; if for no other reason than I will not likely be lulled into a false sense of security.

 

[Doc Harry]

There was a bounce dive like this (200 feet for 5 min) at the resort where I got my OW. I really wanted to do the dive, but the dive op refused to let me go.

In retrospect, I am glad that they did prohibit me from going! Thanks! Now that I know better, I'd never consider doing a dive like that.

 

[lamont]

I believe that Divers run into problems with Narcosis because they go too deep on air, before they're prepared. They lack good buoyancy control and end-up descending too fast (a failure in procedure before IGN is a factor), or fail to recognize that they are being adversely affected (lack of training, or inability to follow deep-diving procedure). It's a bit like a teenager driving at 140 mph on a wet road, getting into an accident and blaming the rain. It went wrong because of how the Driver approached driving and not the fact that it was raining. Go slowly and don't exceed your training and experience.

Kirby was doing deep air 180+ foot dives at least as far back as 2007 when he was doing bounce dives on a single and found the body of another diver (who did a bounce dive to 200+ and died). By the time of his accident last year he'd been doing deep air for at least 5 years and had upgraded to doubles and staged decompression. The site he was at also requires some swimming to get to 180 (at least 10 mins) so he didn't descend too fast.

 

[Kevrumbo]

Deep Air with increased Gas Density & Work-of-Breathing; then throw in Physical Exertion or a Stress Condition, resulting in overbreathing the regulator --all leading to the Vicious Cycle of CO2 Retention and sudden Narcosis. Can result in severe cognitive impairment at depth or worst case stupor and ultimately unconsciousness. . .

Taken from Undersea Biomedical Research, Vol 5, No. 4 December 1978 Hesser, Fagraeus, and Adolfson:
"Studies on the narcotic action of various gases have shown that the ratio of narcotic or anesthetic potency of CO2 and N20 approximates 4:1, and that of N2O and N2 30:1. From these figures it can be calculated that CO2 has at least 120 times the narcotic potency of nitrogen. Our data would suggest that the narcotic potency of CO2 is even greater, i.e., several hundred times as great as that of nitrogen."

 

[DCBC]

Kirby was doing deep air 180+ foot dives at least as far back as 2007 when he was doing bounce dives on a single and found the body of another diver (who did a bounce dive to 200+ and died). By the time of his accident last year he'd been doing deep air for at least 5 years and had upgraded to doubles and staged decompression. The site he was at also requires some swimming to get to 180 (at least 10 mins) so he didn't descend too fast.

My statement wasn't directed at Kirby. Rather "I believe that Divers run into problems with Narcosis because..."

 

[lamont]

My statement wasn't directed at Kirby. Rather "I believe that Divers run into problems with Narcosis because..."

Yeah, and you consistently paint divers who run into problems with narcosis with a broad brush, that conveniently explains why none of those accidents could every apply to you, while discounting any data which doesn't fit your predetermined hypothesis that divers run into problems with because of <things you don't do>...

Its like being stuck in the 1970s arguing with someone who claims they're fine to drive drunk, because....

 

[DCBC]

Yeah, and you consistently paint divers who run into problems with narcosis with a broad brush, that conveniently explains why none of those accidents could every apply to you, while discounting any data which doesn't fit your predetermined hypothesis that divers run into problems with because of <things you don't do>...

Its like being stuck in the 1970s arguing with someone who claims they're fine to drive drunk, because....

You don't know me, so I don't know where you get off telling me what I think and what I do or do not do. You really have no idea. If you have a problem with me, send me a PM and we can discuss it. Otherwise stop spewing out this *rap.

 

[Dr. Lecter]

Its like being stuck in the 1970s arguing with someone who claims they're fine to drive drunk, because....

I'm sorry, maybe I missed it: is a given diver in the 200'-300' range on trimix sober, or just some unquantifiable degree less in the bag than the same diver on air? I won't even make you try to explain how diver A on trimix is necessarily less impaired than diver B on air at a given depth on a given day -- because we both know that there's no way to be sure.

 

[aprivetera]

For me, this comes down to how you interpret the limits that are placed for safety. PPO2 limits. Recommended depth of 30m on air with a recommendd max of 40m. Because after that the chances serious effects will happen will dramatically increase. I have done a number of dives where at 30m I am feeling a little slow but I am with a team and we follow the plan.

Yes, I am not a tech diver but I clearly understand the theory and I recognize the fact that there are mixes out there if I really *need* to go past 40m for some specific purpose for an extended period of time. But it is clear that going past 40m with a single tank of air is just unnecessary if you practice responsible diving.

Can I juggle knives and try to catch one in my teeth? Sure. Should I be surprised if I screw up an it lodges itself in my throat? No. Not even with all the practice in the world.

 

[Dr. Lecter]

But it is clear that going past 40m with air is just unnecessary if you practice responsible diving.

What is clear is that you missed class the day they taught that it's better to remain silent and be thought a fool, than to speak and remove all doubt. "Dive Master Candidate," huh? And people wonder why I get grouchy when random DMs try to "make sure the valve's on" just before I splash.