Instructor bent after running out of air at 40m

[doctormike]

It really is not as scary as it seems--statistics like this can be deceptive.

I am willing to bet that in recreational diving, nearly 99% of the dives are done within limits. That means that about 60% of the DCS cases come from the 1% that are not within limits. If you start with the fact that the rate of DCS is something like 0.002% of dives, and if you consider that most of that tiny, tiny percentage violated those limits, that makes staying within recreational limits pretty darn safe.

Excellent points, John. I would just add one comment.

I don't think that it's a bad thing to let new divers know that it is possible to get bent while doing a recreational dive and staying within NDLs (it happened to me!). It's not that we want them to scare them off, it's just that I think that people should understand that no matter what the magic bracelet says, decompression stress is still poorly understood and there are some variables (hydration, general health, individual susceptibility and anatomy, etc..) that you just can't plug into your dive computer. That also might make people less resistant to getting treatment if they don't have the idea that as long as they followed the DC, any symptoms they have can't possibly be DCS.

In many of the discussions here, new but aggressive divers go on and on about needing the least conservative computer possible so that they can get the most dive time in by going right up to "the line", as if that were the way things work. A little perspective isn't a bad thing.

But I totally agree with you - statistically, you are extremely unlikely to get bent if you follow ANY established algorithm.

 

[dmaziuk]

"Nobody" gets narked at 35m? Allow me to thoroughly distrust such a blanket statement.

:shrug: Debunk whatever you want, my statement was rather more specific than your blanket: not on that particular wreck they don't. I expect Shirley someone has at some point, but our op seemed remarkably unconcerned -- compared to reactions or North Sea divers here, you'd think nitrogen narcosis is something that only happens in your neck of the woods.

 

[wgw04024]

I can't say I've ever experienced it. I've been probably 110-120' max at most on the vandenberg. Lots of trips to the Speigal Grove and Duane.

 

[kelemvor]

When I was certified 40 meters (130 feet) was the recreational limit. .

Me too. I was certified 5 years ago by NAUI.

I thought the only agency who had a shallower recreational limit was GUE, who wanted their divers on helium for dives greater than 100 feet. Maybe I'm wrong.

 

[tursiops]

I've been narced (on air) a number of times, and can sometimes feel it coming on around 100 ft, definitely at 130.
The feeling is one of slight fuzziness, and more task-focus than I am used to. Less situational awareness.
Deepest on air was 185. I do not remember the dive except in vague outline. did the same dive a couple of years later on normoxic trimix; can almost remember all details even now.

I've taught the PADI Deep class to 130 ft a number of times. I'd say about 1/3 of the students show lesser or greater signs of narcosis, especially including no detailed memory of the dive. They, of course, denied feeling anything during the dive.

 

[MaxBottomtime]

I've been narced many times. CO2 narcosis is the worst, usually from moving an anchor at depth or swimming too much. I've always been aware of the narcosis and either ascended until it subsided or continued the dive if it was manageable. Many of my deepest dives were on air including several below 200 feet. I have never forgotten any moment of those dives. If I ever experienced memory loss after a dive I would run, not walk to the nearest neurologist.

 

[gcarter]

I am loathe to say I have never been narced. I can categorically say I have never been aware of being narced. Just over 10% of my dives have been over 90', deepest at 150'. The majority of those deep dives have been on Nitrox of some flavour, if that makes a difference. I know some think yes, some no.

I have always been on the lookout for being narced but have never recognized it in myself or had anything commented to me by a dive buddy.

 

[InTheDrink]

"Nobody" gets narked at 35m? Allow me to thoroughly distrust such a blanket statement.

I don’t seem to get narced now much. But I used to a lot. 23m seemed to be my depth.

Night and day.

Anyhow the whole story smells of BS.

 

[Diving Dubai]

My wife and I both experience being Narced in different circumstances.

For her, she "feels strange" when in poor vis, and may be reluctant to go much below 20m (60'). In good vis then she feels better and is happy at 40m (130')

For me, the onset comes on at around 45m (147') I get more focused and "anxious" contstantly checking guages etc, and as I come back up past 45m I can fel myself relax - back to normal

 

[Lorenzoid]

I don’t seem to get narced now much. But I used to a lot. 23m seemed to be my depth.

Same with me. I attributed the narc to CO2 retention when I was a less experienced diver and less aware of my breathing. Now that I make a conscious effort to breathe properly, I don't feel a narc very often. Or, I can't remember the last time I felt a narc.