Diver dies on 60m deep air dive

[InTheDrink]

P.s. I think but do not know that this is more likely on CCR. NPPE is the more likely cause.

YMMD x

 

[Storker]

On the way back from a PNG dive trip yesterday I was reading a book called "The last new Guinea Salvage Pirate" by Fritz Hersheid, set in the 60's and 70's - the things they did back in the day...

Quite. Back in the day.

Back in the day it was also common to drive a car without seatbelts - and don't even think about child seats in the back - drive a motorbike or a bicycle without a helmet or go boating without a flotation device. And people were dying from crashing without seatbelts, crashing without helmets or falling overboard without vests. And some of those who weren't unlucky and survived love to tell their anecdotes about how they did all these things and survived. Um, yeah, sure. But some of us didn't and can't tell those anecdotes because they're dead. Like some of those I hung out with back in the 70s.

These days we know better, and we have better safety equipment. And fewer people are dying in accidents. I'm also a child of the 60s and 70s, and I really prefer the safety knowledge and safety gear we have today. You won't see me in a moving car without wearing a seatbelt, and you won't see me in a boat without a flotation device. Even if I survived for many years without. Oh, yeah, and you won't see me below 3-3.5 bar pPN2, 1.4 bar pPO2 or 5.5 g/L gas density either. Even if people did those things back in the day. Because these days we know better.

 

[Efka76]

Very nice thread. Especially liked post about attempting woman deep dive record as a fresh OW diver It is good that we live in times when we have more information about safety, much more reliable equipment, specialised training, availability of different gas mixes, software for decompression calculation....still even today accidents happen. It would be interesting to know what was diver mortality rate in 70s - 90s. I guess it was much higher taking into account that people were explored their limits.

 

[johndiver999]

Yes, I'd be very interested to see that. Also skills like cutting a line with a knife, long hose donate, lift bag operation, etc.

I'm not sure you understand narcosis very well. If a diver is very experienced and well practiced in a particular skill, especially a physical skill - like swimming in a straight line, using a knife, working a reel...then they can often function VERY well while pretty deep.

The problem with narcosis is NOT physical skills that have been ground into the diver's subconscious by dozens or hundreds of repetitions, but rather the ability to MENTALLY solve novel problems. Deep air divers are stupid; they think slowly; the may move slower and their inability to problem solve (quickly and correctly), is often not evident until the problem presents itself. That is where the real challenge lies for people who have been acclimated to depth - mental acuity.

The deep air diver may be able to function reasonably safely and perform the typical dive skills perfectly, but when a problem develops, that is where things can go south. Plus, the deep air diver is WEAK. They are breathing a non-optimal gas that is quite dense and if they over-exert at depth, it may be impossible to recover a controlled breathing rate within the short period of time necessary. Inefficient respiration can lead to carbon dioxide build up which has a synergistic effect with the nitrogen and can quickly cause a diver to go from a controlled situation to a tenuous one.

The problem isn't "skills" like cutting a line with a knife!

 

[Graeme Fraser]

I'm not sure you understand narcosis very well. If a diver is very experienced and well practiced in a particular skill, especially a physical skill - like swimming in a straight line, using a knife, working a reel...then they can often function VERY well while pretty deep.

The problem with narcosis is NOT physical skills that have been ground into the diver's subconscious by dozens or hundreds of repetitions, but rather the ability to MENTALLY solve novel problems. Deep air divers are stupid; they think slowly; the may move slower and their inability to problem solve (quickly and correctly), is often not evident until the problem presents itself. That is where the real challenge lies for people who have been acclimated to depth - mental acuity.

The deep air diver may be able to function reasonably safely and perform the typical dive skills perfectly, but when a problem develops, that is where things can go south. Plus, the deep air diver is WEAK. They are breathing a non-optimal gas that is quite dense and if they over-exert at depth, it may be impossible to recover a controlled breathing rate within the short period of time necessary. Inefficient respiration can lead to carbon dioxide build up which has a synergistic effect with the nitrogen and can quickly cause a diver to go from a controlled situation to a tenuous one.

The problem isn't "skills" like cutting a line with a knife!

A valid point. Probably the most extreme display of narcosis I've witnessed was at this very dive site. The diver in question maintained perfect buoyancy, trim and propulsion at 45m, but was utterly oblivious to his team mates. He then proceeded to face the quarry wall and tap his finger back and forth from the wall to his mask. After we helped him ascend he started to become aware of us at about 30m. At the surface he admitted that he had no knowledge of the dive. The point being, apart from the wall tapping he would have appeared to be completely in control, but without intervention I seriously question whether he would have made it.

 

[johndiver999]

I ised to occasionally dive with an experienced diver who would no go past about 100 feet in the local lakes and quarries. He said that narcosis hit him hard, and there was nothing he could do about it. He had been certified for decades at that point.

DW

I also know a few experienced divers who seem particularly susceptible to narcosis. It is not popular to say "I can handle narcosis or I am good deep", but the fact remains that there DEFINITELY are some people who are the complete opposite and they probably shouldn't be diving past 120 ft - ever.

I firmly believe that there can be a wide variability in tolerance to narcosis, and there are some people who have pulled off hundreds of dives at over 200 ft on air, but novices at least, should be cautioned that this is a unique and somewhat unusual subset of the population. People that dont feel right on deeper dives are (hopefully) going to stop going deep on air. This means that the population is probably going through a very significant self selection process.

I doubt there are many people who can do 100 meters every day before breakfast and live longer than grasshopper.

Narcosis is dangerous and you are playing for keeps.

 

[TrimixToo]

LMGTFY...

"The effects of nitrogen narcosis are highly variable among divers with all divers being significantly impaired while breathing air at 60 to 70 meters, whereas some divers are affected at 30 meters. The effects are not progressive with time while depth is maintained, but symptoms progress and new symptoms develop as a diver descends deeper to greater pressures. The narcotic symptoms observed are quickly reversible upon ascent.

"The symptoms seen in nitrogen narcosis begin first with effects of the higher function such as judgment, reasoning, short-term memory, and concentration. The diver may also experience a euphoric or stimulating feeling initially similar to mild alcohol intoxication. Further increases in the partial pressure of nitrogen in the blood from descending deeper lend to impairments in manual dexterity and further mental decline including idea fixation, hallucinations, and finally stupor and coma."

"Nitrogen Narcosis In Diving," Patrick J. Kirkland; Jeffrey S. Cooper."

Nitrogen Narcosis In Diving - StatPearls - NCBI Bookshelf

Add some physical workload that demands more respiration with the high WOB created by a gas density well North of 6g/l, leading to CO2 retention that exacerbates the narcosis and creates an even more urgent need to breathe harder, add some problems to solve...

 

[johndiver999]

I see that paper indicates that Co2 may be additive rather than synergistic with respect to impairment from N2 narcosis. I would accept that correction, since my only real experience is that working hard while deep will kick your butt.

 

[Celt]

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.

 

[John the Pom]

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.