The most important feature of losing cognitive performance is that you are often unaware of losing cognitive performance. A feeling for the passage of time is another casualty, which also impacts on your instrument scan. Interesting point too about the loss of memory, which I first encountered when undergoing hypoxia training, the exact opposite of the situation when diving. I guess the human brain just really likes being in the right range of PPO2.
Was part of an experimental diving team in the military back in the day. We did deep air diving and were proving trimix dive tables. We found with the deep air the one must decend at a steady rate. But with trimix we would could fall very quickly and still have a very clear head at our target depth. Very interesting to listen to this after all these years.
Excellent video! In France, we are trained to go down to 60 meters on air. I've done several 50+ meters dives on air, and indeed narcosis hits hard. Depending on my overall shape (sleep, stress at work...) the outcome of the dive can differ: I've done a 52m dive where I was aware of being narked but that was manageable, and the next day on a 42m dive I had no short term memory and was checking my SPGs every 15 seconds. Helium is the way, you're right. But considering the low number of dive centers that can offer this certification and the price of helium, I'm saving that for later when I get a rebreather. For now, I've gone sidemount for absolute redundancy and I do my deco on O2. Not the best thing, but that's what's available to me. Cheers!
I well remember my first tmx dive. It was so strange to be in45 meters an I still clearly remember everything. After that I've always used tmx when divind beyond 30 meters. It is really worth to do.
I've been UK diving for over 15 years. I'm qualified to 50m. I'd like to say that your videos make so much sense. Excellent content, well delivered. Keep up the good work.
Having been a deep air diver and now having looked at the recent gas density research and gas density tables in addition to your points. I can only agree with you comment 40m max on air. I think I was extremely lucky not to have had an incident in my younger or shall we say stupid days. Thank you.
Totally agree Achem, and well said. I use standard trimix gases below 30 meters. At 45 meters on air, even for very short periods, I know that I am narced. Yes, helium costs more, and you need more training, etc. but if you want to dive below 30 meters, you need both. Otherwise, just stay shallow; plenty to see at 5-30 meters. For deeper, get the training, and use the appropriate gases.
Back in the days I did 70 m on Trimix. Rest of the group was supposed to stay on 55 m on Air. When I met them again they went down to 60 m. Their faces were ... terrible. They were barely functioning.
I once did a wreck dive to around -41meters and i honestly remember close to nothing. The dive went fine.. but i have 3-4 images in my head that i can remember and one of the thing i remember is me trying to think clearly but having a hard time getting what was going on and thinking that this shouldn't happen. I was "only" on -38 meters after all. Looking back i was clearly not a 100%. And i can't imagine how fucked i'd be at -50 meters or even deeper. If you wanna get high, there are much more fun, much safer and healthier ways to get that effect. Diving should be about exploration, learning and discovery (in my eyes). All of that goes out the window when you're narced.
I think that this is still measure of gain and risk. Gain should be interesting dive experience and risk is loss of brain computing power. Is it worth to spend money on helium for this dive? Is this dive safe enough to do it on air? Frankly, I did a lots of dives on air to 40m and sometimes deeper. And if I had to pay for helium, I wouldn't dove. But mostly it was quarry/lake, no waves, no currents, no caves, short deco if any, well known dive site. And these dives made me happy. It was my decision to take the risk and for me it was worth it. But I see the point of Achim and I have to agree on it. Thank you for sharing your experience. Next time I will think even more about the risks.
Thanks for sharing Petr. A big part of our teaching philosophy is the appreciation of risk versus benefit. One of the main factors that contribute to incidents is the "unknown." We don't know what we don't know, and we try (in all humility) to understand and learn as much as we can to mitigate these.
I done 55m deco dive with air. You must very focus all the time, not fun anymore. Check D and gauges all the time, compass and the rest only to be sure remain focus. Besides tunnel vision.
I used to deep air dive when i was younger. I lost a colleague doing it and almost my own life. If you decide to do it at the very least prepare an extra emergency 12 litre tank to be stored at 5 metres with a first stage and 2nd stage regulator on it for an extended emergency stop at five Metres. The biggest mistake people make is underestimating how fast your air supply will be used up the deeper you go. You can literally see the needle move with every breath at depths beyond 40Metres.
i would love to talk about that with you ! In France if you have the FFESSM Level 3 (french federation) you are able to dive without guides to 60m with air, i'm not ok at all with that, but i think that Air is ok (not the best, but ok) if you have a good training and if you dive frequently at those depths. If you go to 60 directly and you havent done deep dive since lot of time, for sure you will have very strong narcosis, but with a controlled descent speed, and you take the time to do 40 meters dives, then 45, then 50 (adpation to depth) if the boat, crewmembers, divebuddies are also trained to those procedures (extra deco tanks under the boat, special training and procedures for those depths) and if you stay behind your limits and your abilities it can be done with safety and without any problems. In france we dive frequently at 60 on air with or without 100%deco tank and i never had any issues with that, the probleme is if it's done the wrong way or if you have a strong reaction to narcosis because you get surprised by it (because of all the aggravant factors) and your buddy doesn't know how to react to that. Before, in the 80' in France diving was limited to 80m on air and the oxygene toxicity and narcosis was a really BIG problem. I think it should be a very special training, with redundant equipment etc ... The problem is that today in france, you take the course for the level 3 and then you can dive to 60 on a single bottle, single first stage, without a special guide, etc ... this is totally ridiculous !
I once gave a 19 Year old Instructor Colleague some advise: The most important thing in deep air diving is to ask yourself "How deep is going to be deep enough?" His reply was to dismiss my concern. One week later he died trying to break his record" RIP James, Aged 19
Not all the symptoms are caused by nitrogen narcosis. My experience is that the feeling of being completely wasted and not remembering much afterwards is usually caused by CO2, not nitrogen. Increased stress and sub optimal breathing at depth will quickly cause CO2 retention in the blood and unlike nitrogen, which is predictable, CO2 will hit out of the blue. Narcosis coincides better with exertion than depth.
It would be good to know how many deaths or accidents happen at say 30-50m on air and how this would compare with rebreather accidents, which I've always understood to be small in number by high in percentage (usage).
Wouldn't it? I completely agree. Unfortunately, a lot of dive accidents aren't reported as thoroughly as we'd like, with most (at least in these parts) described as "drowning." Thus the lack of accurate statistics. Someday.
Hmm... What an interesting question. A good lesson plan for expedition cave starts of course with very strong foundational skills (our BoE equivalent for example). Courses across agencies have their nuisances so it's always good to make sure your training develops you towards your end goal. Since your a technical level, you know what this means. Next would be a proper cave level 1 course that will give you new knowledge not only on basic skills for cave (refined propulsion, line laying, navigation, gas planning) coupled with growing one's awareness about potential problems associated with the overhead environment and, of course, the appreciation of the natural cave. Then time to cement outside of a class with some actual cave dives to your limits. After gaining experience, you take on more skills such as complex cave navigation, multi-stage planning, dpv, ccr possibly even deeper deco protocols which again will depend on your final objective. Each time, stretching one's awareness and competency. It can be a very non-linear approach and you can build your skills based on mini goals at each stage of your growth. You can even add learning from terrestrial cavers as well (srt training, etc). There is emphasis on time in the water, a slow and steady progression to lead to what your ultimate objective is. I hope this helps. Shameless plug: ISE's new modular curriculum allows for this type of learning also. We have the more conventional path of ISE Cavern, Cave Level 1, then Cave Level 2. Or a more modular approach between Level 1 and 2 where you take smaller workshops until you get to a certification equivalency. Cheers and good luck!
I think he means that your brain won't even recognize when it's narc'd but you may realise that you're missing things you normally wouldn't. There are many anecdotal accounts that vary in describing narcosis though so it's also not a one rule for everyone.
Here in the uk there is a dive leader course which certificates a diver down to 50m which is madness in my opinion. Iantd recreational trimix is my option.
Absolute maximum for air dives is 30m IMO, deeper than that different gases strongly recommend to help remove nitrogen from tissues. Safety stops, slow ascent, practice hard and all within limits will make you safe and happy diver ;)
What ever happened to this channel. Cool guy with a personality for TH-cam and he's hunched over saying don't dive without helium past 40m. Get back to the tech and cool stuff. I'm more interested in his watch, Rolex Sea Dweller?
I think it’s important to spend time with a veteran. These lessons are learned, not told. My first breath of compressed air, 1975. I’ve treated around 450 patients as technician recompression chamber. Just be careful.
The most important feature of losing cognitive performance is that you are often unaware of losing cognitive performance. A feeling for the passage of time is another casualty, which also impacts on your instrument scan. Interesting point too about the loss of memory, which I first encountered when undergoing hypoxia training, the exact opposite of the situation when diving. I guess the human brain just really likes being in the right range of PPO2.
Was part of an experimental diving team in the military back in the day. We did deep air diving and were proving trimix dive tables.
We found with the deep air the one must decend at a steady rate.
But with trimix we would could fall very quickly and still have a very clear head at our target depth.
Very interesting to listen to this after all these years.
Excellent video! In France, we are trained to go down to 60 meters on air. I've done several 50+ meters dives on air, and indeed narcosis hits hard. Depending on my overall shape (sleep, stress at work...) the outcome of the dive can differ: I've done a 52m dive where I was aware of being narked but that was manageable, and the next day on a 42m dive I had no short term memory and was checking my SPGs every 15 seconds. Helium is the way, you're right. But considering the low number of dive centers that can offer this certification and the price of helium, I'm saving that for later when I get a rebreather. For now, I've gone sidemount for absolute redundancy and I do my deco on O2. Not the best thing, but that's what's available to me. Cheers!
Not remembering the reading on your SPG is a classic sign of narcosis, at least for me. Passage of time is another.
I well remember my first tmx dive. It was so strange to be in45 meters an I still clearly remember everything. After that I've always used tmx when divind beyond 30 meters. It is really worth to do.
Thanks for sharing your story of past mistakes and helping create a just culture.
I've been UK diving for over 15 years. I'm qualified to 50m. I'd like to say that your videos make so much sense. Excellent content, well delivered. Keep up the good work.
Having been a deep air diver and now having looked at the recent gas density research and gas density tables in addition to your points. I can only agree with you comment 40m max on air. I think I was extremely lucky not to have had an incident in my younger or shall we say stupid days. Thank you.
Totally agree Achem, and well said. I use standard trimix gases below 30 meters. At 45 meters on air, even for very short periods, I know that I am narced. Yes, helium costs more, and you need more training, etc. but if you want to dive below 30 meters, you need both. Otherwise, just stay shallow; plenty to see at 5-30 meters. For deeper, get the training, and use the appropriate gases.
Back in the days I did 70 m on Trimix. Rest of the group was supposed to stay on 55 m on Air. When I met them again they went down to 60 m. Their faces were ... terrible. They were barely functioning.
I once did a wreck dive to around -41meters and i honestly remember close to nothing. The dive went fine.. but i have 3-4 images in my head that i can remember and one of the thing i remember is me trying to think clearly but having a hard time getting what was going on and thinking that this shouldn't happen. I was "only" on -38 meters after all. Looking back i was clearly not a 100%. And i can't imagine how fucked i'd be at -50 meters or even deeper.
If you wanna get high, there are much more fun, much safer and healthier ways to get that effect. Diving should be about exploration, learning and discovery (in my eyes). All of that goes out the window when you're narced.
I think that this is still measure of gain and risk. Gain should be interesting dive experience and risk is loss of brain computing power. Is it worth to spend money on helium for this dive? Is this dive safe enough to do it on air? Frankly, I did a lots of dives on air to 40m and sometimes deeper. And if I had to pay for helium, I wouldn't dove. But mostly it was quarry/lake, no waves, no currents, no caves, short deco if any, well known dive site. And these dives made me happy. It was my decision to take the risk and for me it was worth it. But I see the point of Achim and I have to agree on it. Thank you for sharing your experience. Next time I will think even more about the risks.
Thanks for sharing Petr. A big part of our teaching philosophy is the appreciation of risk versus benefit. One of the main factors that contribute to incidents is the "unknown." We don't know what we don't know, and we try (in all humility) to understand and learn as much as we can to mitigate these.
I done 55m deco dive with air. You must very focus all the time, not fun anymore. Check D and gauges all the time, compass and the rest only to be sure remain focus. Besides tunnel vision.
I used to deep air dive when i was younger. I lost a colleague doing it and almost my own life.
If you decide to do it at the very least prepare an extra emergency 12 litre tank to be stored at 5 metres with a first stage and 2nd stage regulator on it for an extended emergency stop at five Metres. The biggest mistake people make is underestimating how fast your air supply will be used up the deeper you go. You can literally see the needle move with every breath at depths beyond 40Metres.
i would love to talk about that with you ! In France if you have the FFESSM Level 3 (french federation) you are able to dive without guides to 60m with air, i'm not ok at all with that, but i think that Air is ok (not the best, but ok) if you have a good training and if you dive frequently at those depths. If you go to 60 directly and you havent done deep dive since lot of time, for sure you will have very strong narcosis, but with a controlled descent speed, and you take the time to do 40 meters dives, then 45, then 50 (adpation to depth) if the boat, crewmembers, divebuddies are also trained to those procedures (extra deco tanks under the boat, special training and procedures for those depths) and if you stay behind your limits and your abilities it can be done with safety and without any problems. In france we dive frequently at 60 on air with or without 100%deco tank and i never had any issues with that, the probleme is if it's done the wrong way or if you have a strong reaction to narcosis because you get surprised by it (because of all the aggravant factors) and your buddy doesn't know how to react to that.
Before, in the 80' in France diving was limited to 80m on air and the oxygene toxicity and narcosis was a really BIG problem.
I think it should be a very special training, with redundant equipment etc ... The problem is that today in france, you take the course for the level 3 and then you can dive to 60 on a single bottle, single first stage, without a special guide, etc ... this is totally ridiculous !
Święta prawda :)
I once gave a 19 Year old Instructor Colleague some advise:
The most important thing in deep air diving is to ask yourself "How deep is going to be deep enough?"
His reply was to dismiss my concern. One week later he died trying to break his record"
RIP James, Aged 19
Not all the symptoms are caused by nitrogen narcosis. My experience is that the feeling of being completely wasted and not remembering much afterwards is usually caused by CO2, not nitrogen. Increased stress and sub optimal breathing at depth will quickly cause CO2 retention in the blood and unlike nitrogen, which is predictable, CO2 will hit out of the blue. Narcosis coincides better with exertion than depth.
It would be good to know how many deaths or accidents happen at say 30-50m on air and how this would compare with rebreather accidents, which I've always understood to be small in number by high in percentage (usage).
Wouldn't it? I completely agree. Unfortunately, a lot of dive accidents aren't reported as thoroughly as we'd like, with most (at least in these parts) described as "drowning." Thus the lack of accurate statistics. Someday.
What would you describe as the perfect lesson plan for a new technical diver that wants to get into expedition cave diving?
Hmm... What an interesting question. A good lesson plan for expedition cave starts of course with very strong foundational skills (our BoE equivalent for example). Courses across agencies have their nuisances so it's always good to make sure your training develops you towards your end goal. Since your a technical level, you know what this means. Next would be a proper cave level 1 course that will give you new knowledge not only on basic skills for cave (refined propulsion, line laying, navigation, gas planning) coupled with growing one's awareness about potential problems associated with the overhead environment and, of course, the appreciation of the natural cave. Then time to cement outside of a class with some actual cave dives to your limits. After gaining experience, you take on more skills such as complex cave navigation, multi-stage planning, dpv, ccr possibly even deeper deco protocols which again will depend on your final objective. Each time, stretching one's awareness and competency. It can be a very non-linear approach and you can build your skills based on mini goals at each stage of your growth. You can even add learning from terrestrial cavers as well (srt training, etc). There is emphasis on time in the water, a slow and steady progression to lead to what your ultimate objective is. I hope this helps.
Shameless plug: ISE's new modular curriculum allows for this type of learning also. We have the more conventional path of ISE Cavern, Cave Level 1, then Cave Level 2. Or a more modular approach between Level 1 and 2 where you take smaller workshops until you get to a certification equivalency.
Cheers and good luck!
psai narcosis management courses run to a depth of 73 meters using Air as a bottom mix!!! Do they still run these courses, what are your thoughts?
Yes, they do and so do a few more. We don't. ;)
Do I understand you correctly? My body will react without me knowing what's going on? Or understanding too late what's going on?
I think he means that your brain won't even recognize when it's narc'd but you may realise that you're missing things you normally wouldn't. There are many anecdotal accounts that vary in describing narcosis though so it's also not a one rule for everyone.
Here in the uk there is a dive leader course which certificates a diver down to 50m which is madness in my opinion. Iantd recreational trimix is my option.
Great stuff. Can you describe the greatest moment of your life In your next video. stay safe x3
Absolute maximum for air dives is 30m IMO, deeper than that different gases strongly recommend to help remove nitrogen from tissues. Safety stops, slow ascent, practice hard and all within limits will make you safe and happy diver ;)
What ever happened to this channel. Cool guy with a personality for TH-cam and he's hunched over saying don't dive without helium past 40m. Get back to the tech and cool stuff. I'm more interested in his watch, Rolex Sea Dweller?
john metyk if it is,that will explain how he can afford trx on shallow oc dives.....😇😅
I think it’s important to spend time with a veteran. These lessons are learned, not told. My first breath of compressed air, 1975. I’ve treated around 450 patients as technician recompression chamber. Just be careful.