Diving air to 60m

[dmaziuk]

While I agree with you on the existence of outliers, I am still yet to see a scientifically proven of diver not significantly narced at 60m. Them 'handling' and 'feeling ok' is most (99.999...%) likely just them not knowing how badly narced they really are.

Why? If you posit that everybody is narc'ed out of their wits at 60 metres, the burden of proof is on you. "Everybody knows" is not proof, it's a logical fallacy known as argumentum ad populum. Furthermore the claim that "everybody is narc'ed" can be logically proven wrong with a single counter-example.

Scientific proof, you say?

 

[sunnyboy]

The thing is, "back in the day", you had to take deco procedures (a.k.a. deep air) before you would qualify to take trimix. That was simply the progression that was "required" if you wanted the certs so you could dive the gasses with various operators.

That said, if you took deco procedures, there's always a point where you will do your first deep air dive. All the preparation in the world will not substitute for that first experience.

It's also pretty well demonstrated by anecdotal evidence that deep air affected different divers in different ways.

When I did my deco procedures course, the first deep dive was to 140fsw off the B.C. (Canada) coast. I remember the dive quite clearly. Perhaps not as clearly as I do now with some He in the gas, but still pretty clearly. But what I also remember is checking my SPG. And then forgetting the number so checking it again. And again. So I can say I was definitely affected by the PO2 of N2 at that depth, just not the classic way (feelings of euphoria or feelings of doom, etc.). However, another diver on the same dive spent some time with his head in a boot sponge, and did not remember doing that at all.

I would not do that stuff again, but it was "the norm" back then.

Oh, and as for no seatbelts, no helmets on motorcycles, etc. I have just two words for you...

lawn darts. :-D

 

[wgw04024]

On the way back from a PNG dive trip yesterday I was reading a book called "The last new Guinea Salvage Pirate"

Anyone have this book and would like to sell it? It sounds like a great read. I know it's on kindle, but not really my kind of format. Thanks.

 

[Kay Dee]

The thing is, "back in the day", you had to take deco procedures (a.k.a. deep air) before you would qualify to take trimix. That was simply the progression that was "required" if you wanted the certs so you could dive the gasses with various operators.

Agreed. But "back in the day" - for so-called 'techinical diving’ anyway (let's say first and second quarter or so of the 1990’s) - many divers only did the necessary course's to get the certs so they could get the deco gas fills / show a cert to go out on a deep dive boat. That is, some didn't right away go on to trimix, but just completed the deep air and/or deco procedures / technical nitrox courses, and went right back to what they were doing on air (only later deciding it was a good thing to get trimix certified after all ). And some simply did that because helium was not available where they were from.

That said, if you took deco procedures, there's always a point where you will do your first deep air dive. All the preparation in the world will not substitute for that first experience.

But many many folks - in the above category I mention - had already been doing air dives a lot deeper than their 'tech' course dives. That is, their deepest course dives (on air) were much shallower than what they were already diving on air. So their course was not the first time they experienced 'depth' by any means.

I do not think anyone here is recommending not diving gas today, but as much as a surprise as it might be to some, there are no doubt still places / live-aboards in SE Asia, PNG, the Solomons (to mention a few) where helium is not readily available, hence some folks still choose / have no option (save not diving, which to some is not an option) but to dive air.

But what I also remember is checking my SPG. And then forgetting the number so checking it again. And again. So I can say I was definitely affected by the PO2 of N2 at that depth, just not the classic way (feelings of euphoria or feelings of doom, etc.). However, another diver on the same dive spent some time with his head in a boot sponge, and did not remember doing that at all.

While there is no debating the benefit of helium based mixes at depth, personally I found myself much more 'cautious' as it were in my approach as to what I did at depth whilst on air, as opposed to being much more adventurous at (much deeper) depth whilst breathing helium based mixes. That is, I certainly kept myself very aware of my limitations when deep on air! As a matter of fact, I have felt more narced - well I assume that's what it was - at 30m on a very cold, dark, low-vis Baltic Sea air dive - where I was significantly under-weighted - than I ever did at 60m or so on air in the tropics. Was I significantly narced, no, but I sure wasn't comfortable in my surrounds!

I would not do that stuff again, but it was "the norm" back then.

Well, if I did I would certainly try not to spend too long with my head in a barrel sponge , but................... if there was no other option than air, and the conditions warranted it....................

Anyway, I do not think this thread has veered into debating whether folks should dive deep on air, or the merits (or lack there-of) of deep air diving, certainly I am not, nor am I just for the sake of it. But by the same token I can't just stand aside and not address the narcosis issues that have been raised in this thread.

 

[Kay Dee]

Anyone have this book and would like to sell it? It sounds like a great read. I know it's on kindle, but not really my kind of format. Thanks.

The book is still available second hand ex Australia, but at a rather hefty price.

Just look it up on ABEbooks, or Bookfinder, etc. I don't think the Kindle version would do it justice, but better that than nothing.

I highly recommend this book - The Last New Guinea Salvage Pirate - to anyone with an interest in history!!!!!

 

[mafi]

Why? If you posit that everybody is narc'ed out of their wits at 60 metres, the burden of proof is on you. "Everybody knows" is not proof, it's a logical fallacy known as argumentum ad populum. Furthermore the claim that "everybody is narc'ed" can be logically proven wrong with a single counter-example.

Scientific proof, you say?

Wait what.... Earlier in this thread I said that we have scientific evidence that everybody in 60m is narced. I never said “everybody knows”, which you are attacking me for. Look for ‘The strawman’ in your list of logical fallacies.

Btw I stand behind what I said. We have many studies saying everybody is to some extent at even only 30m, let alone double the depth. Still, no study, even just one counter-example of clear headed person at 60m on air.

If so, I’d be happy to read it.

/sarcasm/ Maybe there is no recoded account of this as people at 60m on air just dont remember it? /sarcasm/

 

[Wingy]

Kay Dee's point about area specific availability of gases in remote areas is a big factor too in why I continue to dive air. I dive in the coral triangle and South Pacific - I prefer remote remote diving, and if an island is dependant on a supply ship once a week or fortnight then you best get used to diving air especially with land based ops.
I know of one op in Vanuatu that has He and breather support and all your exotic blends....but....when you're talking a LOB and consecutive air dives in the even 30m - 35m range shouldn't a diver have some knowledge of how they are supposed to feel? Surely if I did a 35m dive early morning then a 35m next day - adhering to my deco obligation because I know it's true deco - if I felt light headed and "narked" surely I'd notice something?

At 60m on air - a few crazy old French people on an island in the Andaman gulf used to start the day with a 100m air bounce before breakfast. I stayed at their "resort" and had breakfast every morning for a week with them post bounce....all seemed capable of normal breakfast type conversation and ate their croissants the right way. Never saw them in the water during their wake up dive though. Apparently they had been doing it for years.

 

[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.

 

[mafi]

While I agree with you saying that drilled skills are not that much on an issue with narcosis, any small deviation from the task is ‘exponentially’ more complex for narced diver.

Cannot move - am I tangled? - where is the line? - can i back out? where should i cut it? - from which angle?

Same for OOG: The actual move to provide reg for sharing might be ALMOST as fast as in shallows, recognizing the situation that would require it definitely not.