Diving air to 60m

[beester]

I had never noticed the increased gas density issue before on deep air dives so I watched out for it on last nights dive. Still didn't notice it even though I was looking for it. St. Lawrence river, 160 feet, occasionally swimming against ~2knot current in full tech gear with 2 stages.

I think, just like almost everything else in diving, it can be an issue for some but not for others. So it is inappropriate to make blanket statements

I'm not making any blanket statements... I'm basing this on fact. There is proof that your risk level suddenly really jumps once you increase gas density above 6gr/L. (which is 40m on air)
Gas density guidelines

Does that mean that there is no personal variability in place... yes for sure there always is... we are humans. But I have enough deep experience on air and trimix to know that variables can suddenly change deep underwater, and what was maneagable just 1 minute ago is no longer maneagable the next, just with a sudden shift of workload, increase of breathing, etc.. I mean I've personally have seen this effect at only 40m while working hard... WHAM! Why take the risk when there are alternatives?

Anyway the context of this was a death at 60m, on air, single tank, no experience... and a lot of people (also I) contemplating what might have caused this, and for me together with the failed BCD the elephant in the room is deep air. Doesn't mean you can't dive deep air, doesn't mean I'm attacking your personal liberty to do what the hell you want... but I find it funny that divers doing it always come up with the same response to scientific study and deep air diving:

- I'm different (maybe better, more experienced?), it doesn't apply to me
- I've been doing it for years, it hasn't killed me so I'm right.
- My personal circumstances are such and such that trimix is not possible (gas logistics, money, training, buddies)
- JJ Cousteau (insert whatever big name old school diver from the past) did it so it can't be wrong.

I mean come on guys... just for the sake of this forum, and for new divers making up their mind on things... at least own up to what you do! I'll dive to 40m on air, and maybe even to 45m if it's just a tropical bounce dive in the red sea, yes I've done deep air dives, yes I liked being narced out of my mind at a certain stage in my diving career... yes I felt special doing those dives on air... but at least acknowledge what is being proven the last decade (PPO² limits, EAD limits, Gas density limits), instead of above excuses.

 

[mafi]

I fully realize this guy claims to have 5k dives.

Regardless of that, he explicitly admits to be above tank filling rules and implicitly ignoring latest research on narcosis.

What is clear is that mr 5k dives is not the one learning in the process and deliberatly choses to engage in arguably unsafe diving practice.

We have enough data to prove that introducing helium to the mix significantly increases safety and decreases mortality of deep wreck divers.

 

[Wingy]

I dive air. I like it. There is no cost factor involved, I have my reasons for diving air and sometimes wonder why I have to have the "What do you mean you don't dive Nitrox!" Lecture so often. I don't poke my nose into people's choices of which gasses when and how....can't I just dive air? I'm not a record setter, not a professional, not anything but just an average but well travelled diver so deep air to me is only in the 50m range. I have no intention of going to 150m. If I'm close to 50m it means they're is something to see, I don't just hit that "limit" to prove anything.

Re Narcosis...still waiting, have not noticed it at all yet. I read an article on personality types and how that too can increase or decrease a persons predisposition to being noticeably narked. If physiology does it makes sense that psychology would play a part too I'd imagine.

 

[Bob DBF]

You should make yourself familiar with dive fatality rates since deep air diving has mostly ceased. Deep and air are a deadly mix for the various scientific reasons given in this thread i.e WOB, narcosis etc.

You assume quite a lot.



Bob

 

[cathal]

You assume quite a lot.



Bob

I have made no assumptions, I’m just basing my comments on deep air diving fatality rates, that’s all.

 

[Bob DBF]

I have made no assumptions, I’m just basing my comments on deep air diving fatality rates, that’s all.

You assume I don't read, for a start.


Bob

 

[runsongas]

Easy dive a breather. (yes I know it's expensive)

But the context here is 60m air diving... Would like to know if you regularly do 60m or deeper air dives with a significant bottom time (say +20 minutes)...

rebreathers aren't a panacea though, they have their own set of hazards and failure modes you don't find on OC.

 

[Kay Dee]

I mean come on guys... just for the sake of this forum, and for new divers making up their mind on things... at least own up to what you do!

OK, since you asked, if gas was not available, I would dive and have dived OC air on 100's and 100's of occaisions (maybe more than a thousand?) on wrecks, for up to 30 minutes BT, and have not ever had a problem - that I couldn't solve - with dives in the 60m or so range on air in tropical type waters, although not always in great vis. (And did so, when there was no other option in a remote location, long, long after I was trimix certified in 1993.)

My only proviso would be that I did not do the shallow deco on air, but on o2, or some high o2 mix.

Would I rather do it on gas, and do it on gas on a CCR if I could, yes of course, but I would not forgo a dive to that depth - with an objective in mind; photography / wreck survey in my case - if neither was available, as a matter of fact I wouldn't hesitate to do it.

Would I do that dive with you @beester, probably not by the sounds of it, but if it was John Bantin (who dropped the 'deep air' hand grenade that started this back and forth) and a few others I see here, then I wouldn't hesitate. (And no @beester, I have never felt/been 'narced out of my mind', nor would that ever by an objective of a dive I did. I have always completed the task I set out to do - well, post my course dives that is - be it photography, survey, even body recovery.)

However, I would not recommend others dive deep air, but neither would I preach to others that they shouldn't do it (unless they were inexperienced at depth), but you asked for an honest answer, so my reply is simply what you asked for.

As for the history of all the deep air fatalities, what about the history of all the deep air accomplishments / opening of doors - pre-gas (helium) diving - to what was possible in both caves and wrecks. [Hopefully one day M2 (Michael Menduno for those too young / too new to know ) will get his book published on the early days of 'technical diving' - so those that think either the devil, or God forbid the master stroke himself, GI3, will pop out at 60m to snatch you away - so folks later to the scene can see what accomplishments (and fatalities) were made once upon a time, deep on air.]

Be that is it may, this is NOT a recommendation for deep air diving, of course dive gas whenever possible, but however hard some folks try, you can't hide the fact of what was accomplished back in the day on 'deep air' (and can still be if the situation demands).

Oh, and just so you don't think I say the above while hiding behind a forum moniker, my name is Kevin Denlay. And, with all due respect, if you don't like my reply then don't ask the question.

EDIT: Given this thread has strayed somewhat into deep air diving as a whole, as opposed to the accident itself, and with due condolences to the family and friends of the deceased, I would certainly not advise a dive of the nature that the accident happened on for a person on a single cylinder.

 

[beester]

I would dive with you kay dee and i like your honest answer.

 

[almostDIR]

I don't understand why anyone would want to bounce dive to 60m on air for something like 1min of bottom time unless it is some kind of narcosis experiment or just wanting to get "a little bit of deco" for the sake of it?
anything other would require some deco time so would be much more practical to at least add doubles and probably some deco mix even if wanting to dive on air if trimix is "too expensive".

Thankfully it is possible to get great discounts on scuba helium here so it is not financially prohibitive to dive trimix and I surely will when I'll get to the point of being experienced enough to do deco dives