How do you learn your narcosis depths? Gas switches?

[Miyaru]

I think you can never determine yourself if you're impaired by narcosis to a certain degree.

Go deep (> 130ft/40m) on air and perform a task (eg. attach a lift bag to an anchor & make it neutrally buoyant) and (have someone) film it, preferably with a camera placed statically on the bottom. Watch it after the dive and consider the amount of real time it took you, compared to the amount of time you thought it took.

 

[Celt]

I'd like to skip rehashing the getting good at working on narcotic gases debate! It has been well hashed.

I'd rather we focus on how you find the depths at which we are affected (for the local conditions, activity level and good respiration rate).

Fair enough, but been good or bad on a control test in a chamber won’t work for people. You need to learn your own threshold and what works for you under the conditions you’re diving in. The things I ask myself are, how do I feel? What at the conditions and what do I need to get done?

 

[ChuckP]

I can almost make myself narced at 80' with a hard kicking rapid descent head down but I think it is way more CO2 and being winded than anything. I get to the bottom and enter a "cave" here and it's like wow - it's happened twice but I knew something wasn't right and sat out of the current and took a few good breaths and the world comes back to crystal clear rather quickly.

The comments about the shallow breathing and working hard are exactly what really brings it on for me - you sense it and just stop the work and get good breaths - it works for me.

I do do 150-170' on air with no problems - here in Cozumel. I don't work at all and every other minute or so I take a deeper breath than normal, slightly faster inhale and exhale to clean CO2 out in case that would cause a problem. My regulators breathe wonderfully at that depth so you really do not notice much change in WOB. I am just fully aware and self evaluating all the time when diving deep - any sign of problems, we either stop the work or go up, it's that simple.

 

[Akimbo]

Go deep (> 130ft/40m) on air and perform a task (eg. attach a lift bag to an anchor & make it neutrally buoyant) and (have someone) film it, preferably with a camera placed statically on the bottom. Watch it after the dive and consider the amount of real time it took you, compared to the amount of time you thought it took.

I submit that comparing it to how much time you though it would take is also true when working at half that depth. I have watched endless hours of commercial divers through hat and ROV video cameras. Many were working on fairly complex tasks, breathing air, and between 130'/40M and 200'/60M. I could also verbally communicate with them. There is no question that their dexterity is less and they aren't as articulate as they are at 60'/18M. They are slower and more deliberate for sure. But the same is true when comparing their work on deck.

I don't ever remember having to stop a diver from doing something dangerous/stupid. That said, recreational divers are free to dive Trimix in 30'/10M if it makes them feel better.

 

[Scuba Client]

My first thought when I read the post was an analogy......

would you practice driving drunk to see how it affects you? A bit tongue in cheek but still.....

certainly dives that are layered in good choices for safety could be used as tests for narcosis affects...but there are so many variables that any results would be highly anecdotal.

Best to use air/Nitrox for 100’ dives or less and throw some He in there when deeper. Several progressive agencies use an EAD of 100’ for a reason.

Nitrox for dives to 45 metres, any deeper and you should switch to CCRs if you're affected by narcosis.

 

[Centrals]

Nitrox for dives to 45 metres, any deeper and you should switch to CCRs if you're affected by narcosis.

How many precious min do you get from using EAN24 over EAN21?
No I won't bother.
Switch to CCR and use trimix!!!

 

[MichaelMc]

Lots to think about and pay attention to as I go deeper. Thanks.

Hmmm. Had you been diving with that computer for a long time? Were you just reading the default display or scrolling through menus? What was the nature of your confusion?

The confusion was from a 5 minutes to NDL alarm. I'm used to understanding why electronics are beeping at me fairly quickly and this confused me at 100', and one other time at around 90'. My response was ascending a bit and assessing the situation more carefully. I'd used the computer for a while, but it does not have the most intuitive display.

My thought on the survey was of how often you feel lost on which urchins you had already counted. Or how difficult it was to add up hash tallies into numbers.

Switch to CCR and use trimix!!!

CCR is likely eventually. For now I'm sticking with the simpler open circuit with some dives venturing into the narcosis realm. I'd rather know that I can as I go there, and got a rec trimix cert for that. My deep qual was a while ago, so I've forgotten what that may have felt like on air. And separating that from the unfamiliar, cold, and dark. Reliving it without mix handy seems a bit like driving drunk to remember, but without an offramp for the drunk, to reuse an analogy.

 

[johndiver999]

I don't think I often exhibit any symptoms of narcosis at 100 or even a little deeper. But if your "symptoms" are a decrease in sharpness, clarity of thought, attention to detail, ability to count or keep track of something. Those are not really unusual or surprising or even concerning symptoms.

As I mentioned before, if you are going deep (whatever that is for you personally) then you need to prepare yourself for "being stupid". Make decisions slowly, try to avoid coming up with new and "bright ideas" on a dive. Stick to what you know, watch your gauges like a hawk, if you feel really strange or nervous, then bail, don't be surprised when you check your gauges, determine they all look "OK" and then 2 seconds later have a hard time remembering what they showed other than "All OK".

Try to set a more simplistic dive plan, have HARD numbers for NDL , DECO and remaining air. For deep dives, I like to set my G-shock watch on stop watch mode, so I have an independent time clock and if you have planned your air supply with a good bit of padding (as you should) , then you often can get all the information you really need by just checking elapsed time. I check time pretty frequently when diving "deep" on air.

If you do all this (and your diving skills are all automatic) AND you avoid exertion, you should be able to count urchins etc.

 

[Graeme Fraser]

Reminds me of the perennial YouTube classic 'diver in a knot'.

 

[Bob DBF]

I think you can never determine yourself if you're impaired by narcosis to a certain degree.

From my experience one can, however it takes a good mentor and practice. First I assume I am impaired past 100'. It is not easy to describe, nor will I be able to accurately know how impared I am, but I did learn when to quit. I do work up dives before going deep to practice and gauge my abilities, and insure my breathing won't work into a CO2 hit, which only makes matters worse. Without work up dives I won't break rec limits.

I can almost make myself narced at 80' with a hard kicking rapid descent head down but I think it is way more CO2 and being winded than anything.

A CO2 hit is not nitrogen narcosis. The symptoms of narcosis are stupidity and narrowing of focus, neither of which are easy to determine on your own, and unlike alcohol, you will have no physical clues of your condition.