Diving air to 60m

[dmaziuk]

Are you gonna hold the other side in this argument to the same standard?

No because if your argument is some divers on some dives get more narc'ed than others, I completely agree. Or that a dive to 60 metres is just in general more risky than a dive to 30: sure is.

You seem to be implying a trend: everybody who dives to 60 metres on air is playing Russian roulette and will be stoned senseless and will get themselves killed. That's just scare-mongering rubbish with no "scientific" backing for it.

Accidents can happen to people on the surface with trimix in their CCR, and have. Helium rebreathers kill!!!

 

[beester]

No one in their right mind would tell a novice to dive to 60 meters on air. New diver are going to learn the effects of narcosis long before that and it’s up to them to deal with it. If a divers feels impaired they simply ascend a few meters and the symptoms will immediately subside. Narcosis is not some boogie man waiting in the darkness to pounce on you. Learn to recognize it and deal with it.

I'm sorry but it is a boogie man waiting to get you! It's not called nitrogen narcosis, it's called hypercapnia. If you exert yourself at depth in the wrong circumstances you could get hit by CO² and it's massively more narcotic than N², next you don't get rid of it by just simply ascending a few meters. I've dived in the North Sea to this depth range on air... in current, doing work... and I'm sorry to say it can hit you like a freight train out of nowhere.

To the others some interesting comments were made:

@ Kay Dee: I agree with you but on this topic quite some people have posted to regularly dive deep air even in spots where He is easily available.

- On being more narcosis proof or not. I know a rec diver (but cmas rec diver with a 3* cert which allows him to dive to 60m on air), who always wants to go "deep", but whenever he goes below 35-40m he goes bonanza... totally losing the plot, getting really stressed out, moving very fast, thumbing the dive out of no where... Suffice to say he doesn' have a lot of buddies when he wants to go "deep".

- On N² narcosis (no CO² narcosis): Yes you can build up to it...not on the narcosis but with experience you can negate a lot of scenarios... just like a drunk driver can still shift gears... it's when you suddenly need to use your brain, your mental bandwith... when a question rises, that you realize (or not) that you don't have the bandwith left to compute the question. Example from me personally. I was doing a north sea dive at 46m on air with a buddy... we were on the wreck and he suddenly gives me the sign to take over the dive (meaning I lead the dive, do the navigation, run the ascend/deco). I ask him (questionmark signal) why? He shows me his computer... Guys... no kidding I'm looking at his ******* computer for 30secs... and I can't see a reason why he asks me to take over... We finish the dive, and ascend... at first real deco stop (12m) I ask him to show me his computer again.. and immediately I notice that the depth is fixed at 26m. This is not some small symbol in the corner of the screen.. it's the bloody depth, and at 46 m he saw that his computer had blocked (depth still at 26m) and asked me to take over... I saw this immediately at 12m, and for 30 seconds I checked his DC at 40ish m without noticing a thing! That's N² narcosis in a nutshell!

Finally I invite everybody of you to dive the same wreck (40-60m range) on air... and as well on trimix. If you don't see the difference you are lying! On air you dive in a coccoon... your focus is limited, you see literally less far, it's like you have snapshots of the wreck... on trimix you can see the whole wreck in 1 go... the tight dark passage you dived to get to a room is suddenly not so tight and dark anymore... it really is a big difference, irregardless of "experience", "training", "competence"...I've done this both on med wrecks and north sea wrecks and the effect is the same.

Cheers

B

 

[KenGordon]

To move the discussion on, should it have been 18/35 or 18/45 in the single 12?

 

[wetb4igetinthewater]

@Bob DBF,

Didn't you post a great quote from a mentor about the problem of narcosis? Something along the lines of when you are dealing with an emergency and are task loaded, then you discover how much of an issue narcosis is.

 

[chillyinCanada]

Just a personal anecdote, but many years ago we did air dives to ~50 msw to look at wrecks off Sydney. We were diving on tables, with detailed dive profiles & air consumption planned out on slates. We were all affected by narcosis to varying degrees at that depth, but all the divers were able to follow the dive plan fine. On one dive though we had a person who became badly narc'ed. He was diving on independent twins, and he simply couldn't work out the relation between his SPGs and the regulators. He kept removing one regulator and then putting the same one back in, and he couldn't understand why the pressure in one tank was dropping and the other one was still full. He knew something was wrong, but he couldn't work out how to fix it. His buddy helped him and after they ascended a short distance he was fine again.

Afterwards we had a good laugh about it, but he obviously couldn't dive to that depth safely on air. There was nothing in terms of age, fitness, etc. that set him apart from the rest of us, but his ability to reason his way through simple tasks just evaporated once he hit about 45 m.

On every dive to that depth or only the once?

 

[Bob DBF]

@Bob DBF,

Didn't you post a great quote from a mentor about the problem of narcosis? Something along the lines of when you are dealing with an emergency and are task loaded, then you discover how much of an issue narcosis is.

I was told by one of my mentors, the real problem with narcosis is not knowing you are narked, then finding out during an emergency that you are. That surprise may last long enough to kill you.

That bit of information has served me well, and I dive deep like a long tailed cat in a room full of rocking chairs.



Since I have less reason to get too far outside of rec limits as I get older, I choose to stick with my training. If I was to continue to do big dives, my choice would be different. Other divers should make their choices on their needs and the variety and quality of training that is available today.


Bob

 

[Celt]

I'm sorry but it is a boogie man waiting to get you! It's not called nitrogen narcosis, it's called hypercapnia. If you exert yourself at depth in the wrong circumstances you could get hit by CO² and it's massively more narcotic than N², next you don't get rid of it by just simply ascending a few meters. I've dived in the North Sea to this depth range on air... in current, doing work... and I'm sorry to say it can hit you like a freight train out of nowhere.

To the others some interesting comments were made:

@ Kay Dee: I agree with you but on this topic quite some people have posted to regularly dive deep air even in spots where He is easily available.

- On being more narcosis proof or not. I know a rec diver (but cmas rec diver with a 3* cert which allows him to dive to 60m on air), who always wants to go "deep", but whenever he goes below 35-40m he goes bonanza... totally losing the plot, getting really stressed out, moving very fast, thumbing the dive out of no where... Suffice to say he doesn' have a lot of buddies when he wants to go "deep".

- On N² narcosis (no CO² narcosis): Yes you can build up to it...not on the narcosis but with experience you can negate a lot of scenarios... just like a drunk driver can still shift gears... it's when you suddenly need to use your brain, your mental bandwith... when a question rises, that you realize (or not) that you don't have the bandwith left to compute the question. Example from me personally. I was doing a north sea dive at 46m on air with a buddy... we were on the wreck and he suddenly gives me the sign to take over the dive (meaning I lead the dive, do the navigation, run the ascend/deco). I ask him (questionmark signal) why? He shows me his computer... Guys... no kidding I'm looking at his ******* computer for 30secs... and I can't see a reason why he asks me to take over... We finish the dive, and ascend... at first real deco stop (12m) I ask him to show me his computer again.. and immediately I notice that the depth is fixed at 26m. This is not some small symbol in the corner of the screen.. it's the bloody depth, and at 46 m he saw that his computer had blocked (depth still at 26m) and asked me to take over... I saw this immediately at 12m, and for 30 seconds I checked his DC at 40ish m without noticing a thing! That's N² narcosis in a nutshell!

Finally I invite everybody of you to dive the same wreck (40-60m range) on air... and as well on trimix. If you don't see the difference you are lying! On air you dive in a coccoon... your focus is limited, you see literally less far, it's like you have snapshots of the wreck... on trimix you can see the whole wreck in 1 go... the tight dark passage you dived to get to a room is suddenly not so tight and dark anymore... it really is a big difference, irregardless of "experience", "training", "competence"...I've done this both on med wrecks and north sea wrecks and the effect is the same.

Cheers

B

Hypercapnia, a favorite buzz word among divers and a non issue on open circuit, not only did I work hard on air but used crow bars, water lances, cutting gear. lifting bags and laid explosives without suffering as much as a minor headache. Anyone with any symptoms of carbon dioxide toxicity using open circuit diving gear needs to consult a professional it is not normal.

 

[John the Pom]

On every dive to that depth or only the once?

That was his first dive past 40 m, and I hope it was his only dive to that depth on air.

 

[mafi]

@mac64, do you realize that high gas density (above 6g/l) significantly increases WOB that can easily lead to hypercapnia, as you just cannot sufficiently expel CO2?

Granted, It's different case than in rebreathers, where the scrubber is the culprit, but hypercapnia is an issue on OC nonetheless.

Feel free to educate yourself when your hands get tired from all the chest-thumbing

Alert Diver | Performance Under Pressure

Video, if you are more visual:

Primary sources:
1. Anthony G, Mitchell S. Respiratory physiology of rebreather diving. In: Pollock NW, Sellers SH, Godfrey JM, eds. Rebreathers and Scientific Diving. Proceedings of NPS/NOAA/DAN/AAUS June 16-19, 2015, Workshop. Durham, NC; 2016; 66-79. Available at: https://www.omao.noaa.gov/sites/default/files/documents/Rebreathers and Scientific Diving Proceedings 2016.pdf. Accessed March 25, 2019.
2. Warkander DE, Norfleet WT, Nagasawa GK, Lundgren CEG. CO2 retention with minimal symptoms but severe dysfunction during wet simulated dives to 6.8 ATA abs. Undersea Biomed. Res. 1990; 17(6):515-523.
3. Lambertsen CJ, Gelfand R, Lever MJ, Bodammer G, Takano N, Reed TA, et al. Respiration and gas exchange during a 14-day continuous exposure to 5.2% O2 in N2 at pressure equivalent to 100 FSW (4 ATA). Aerosp. Med. 1973; 44:844-849.
4. Doolette DJ, Mitchell SJ. Hyperbaric conditions. Comprehensive Physiol. 2011; 1:163-201.

 

[Celt]

@mac64, do you realize that high gas density (above 6g/l) significantly increases WOB that can easily lead to hypercapnia, as you just cannot sufficiently expel CO2?

Granted, It's different case than in rebreathers, where the scrubber is the culprit, but hypercapnia is an issue on OC nonetheless.

Feel free to educate yourself when your hands get tired from all the chest-thumbing

Alert Diver | Performance Under Pressure

Video, if you are more visual:

Primary sources:
1. Anthony G, Mitchell S. Respiratory physiology of rebreather diving. In: Pollock NW, Sellers SH, Godfrey JM, eds. Rebreathers and Scientific Diving. Proceedings of NPS/NOAA/DAN/AAUS June 16-19, 2015, Workshop. Durham, NC; 2016; 66-79. Available at: https://www.omao.noaa.gov/sites/default/files/documents/Rebreathers and Scientific Diving Proceedings 2016.pdf. Accessed March 25, 2019.
2. Warkander DE, Norfleet WT, Nagasawa GK, Lundgren CEG. CO2 retention with minimal symptoms but severe dysfunction during wet simulated dives to 6.8 ATA abs. Undersea Biomed. Res. 1990; 17(6):515-523.
3. Lambertsen CJ, Gelfand R, Lever MJ, Bodammer G, Takano N, Reed TA, et al. Respiration and gas exchange during a 14-day continuous exposure to 5.2% O2 in N2 at pressure equivalent to 100 FSW (4 ATA). Aerosp. Med. 1973; 44:844-849.
4. Doolette DJ, Mitchell SJ. Hyperbaric conditions. Comprehensive Physiol. 2011; 1:163-201.

The increase in WOB at 60 meters is hardly noticeable and a load of hype. Maybe you should do a bit of chest thumping it might improve your lung function.