Rodale's pushing deep air.

[Curly]

Mike --

Thanks for the informative post. Like you, I receive this mag although my subscription ran out years ago (actually just started receiving it again within the last four months). I read this article, and was considering asking about it here on the board. Your insights are much appreciated. As someone who still dives air (taking Nitrox this year), but who has only been to 100 feet (and only a handful of times), I was curious. It seemed to fly in the face of everything I'd read from knowledgeable posters here on the board.

Great post.

 

[H2Andy]

i dont' know.. i used to read (not buy) Rodale's quite a lot back in early 2002, maybe mid-2002, but slowly, i just got tired of all the ads and the obvious tie-ins with their
advertisers and content... not that they didn't have some useful articles, but i just
kept finding less and less that was new to me or helpful... so i sort of naturally
gravitated away from it...

that's just my own story, i can see how people might find Rodale's useful

 

[IndigoBlue]

i dont' know.. i used to read (not buy) Rodale's quite a lot back in early 2002, maybe mid-2002, but slowly, i just got tired of all the ads and the obvious tie-ins with their
advertisers and content... not that they didn't have some useful articles, but i just
kept finding less and less that was new to me or helpful... so i sort of naturally
gravitated away from it...

that's just my own story, i can see how people might find Rodale's useful

Its a great scuba magazine for beginners. Given that, the deep air article probably did not belong in there, or else definitely should have presented both sides of the issue instead.

 

[MikeFerrara]

I therefore agree with MikeF's notions about the article, although not with his own unbalanced reply to it.

Writing to RSD with your own view of the topic would accomplish more than anything else.

I don't know what you mean by unbalanced.

I didn't really even comment on the deep air issue much.

I disagreed with the authors description of the rule of thirds. IANTD, NACD, GUE and the NSS-CDS all seem to see it my way or... I see it theirs.

I disagreed with the authors statement that you needed to use a travel gas when diving trimix. That's not always true at all. it is true with a hypoxic mix but other than that you are no more likely to use a travel gas than on an air dive.

I disagreed with the authors suggestion that miltiple gasses were needed when using something other than air but not with air which also isn't true. It is common for divers to use oxygen (or other mix with a higher FO2 than air) for decomrpession on air dives also. At the same time you can do a dive with trimix on a single gas (as in the IANTD, NAUI and GUE recreational trimix classes)

I don't think these points are one sided at all.

As far as writting to Rodales, I let them know that I posted here about their article so they could have their say if they wanted. However, I wasn't interested in discussing the issue with them or changinf their mind. I'm not interested in fixing anything that might be wrong with their magazine. My only interest was presenting a different point of view to some of the divers who might typically read Rodales.

If any one wold like specific references regarding the points I made in the opening post or above just ask and I'll dig up page numbers and direct quotes from the texts of the above mentioned agencies.

 

[IndigoBlue]

OK Mike, here is what I mean by one-sided, on your part.

First, you have criticized him at every turn, without giving him any credit for his "few" valid points. For example, diving with only air is as a matter of conclusion "simpler" than diving with several mixes.

Second, you have steered clear of his intended point, the safe-ness of air, and instead you have steered onto all sorts of peripheral issues. I did not agree with his definition of the Rule of Thirds either, however that is only tangential to the main theme of the piece.

He does in fact, as you say, try to make a case for the safe-ness of deep air based on its long term historic use and the asserted lower level of fatalities of divers diving with air compared to technical mixes. But he does not document that, and neither do you document your rebuttal. Both of you are one-sided in your presentations.

If you read his comments about the complexity of trimix diving, carefully, you will see that he has cleverly stated the truth. He made it sound worse than it is, but what he says is true. You probably did not read it carefully enough.

I do not see any self-contradiction by the author. On the contrary, he is very consistent about repeating his arguments in favor of air diving as being more simple than trimix diving. What he does not do is address the other side of the issue, which you do not do either. That is my point, about one-sidedness.

I do believe the article needed more work, before going to press. And I think your response would have been more effective if you had toned down your counter attack somewhat.

Of the two of you, Mike, YOU are more correct than the author, in my opinion. But you each could have done more to represent the other point of view in your response.

Before I start I'll admit what many of you already know which is that I have little use for this magazine. After having a dive shop for a couple of years I got rid of it and wouldn't sell it. Now, I don't ask for it and sure don't pay for it but they just keep sending it to me.

Yesterday the May issue came. I skimmed through it during a commercial last night and my eye was caught by an article titled "Is Deep Air Diving Safe?" by Michael Ange

BTW, I put this post here rather than the technical section because the magazine is a recreational diving magazine and is read by recreational divers so I wanted to address my comments to recreational divers.

I'm not going to comment on how deep I am willing to use air or what I think your maximum depth on air should be. I must, however, comment on a couple of points made by the author that sent my BS meter streight through the roof.

The article...

He starts by stating a case for deep air based on it's good safety record. I won't spend much time here other than to say that there is plenty of reading out there to the contrary but it's a wast of time to talk about it without getting into specific depths. I will say that if air was so great we sure wouldn't mess with the cost and trouble of other gasses.

Next I have to address his comments on trimix. For those who don't know...trimix is a mixture of oxygen, nitrogen and helium. The helium is used primarily to displace some of the nitrogen (reducing narcosis) and oxygen (limiting oxygen exposure). At sufficiently high partial pressures and or periods of time oxygen becomes toxic.

ok, on to what Michael Ange said...I quote

I call BS in that a travel gas isn’t needed unless diving a hypoxic mix (Not enough O2 to keep you alive near the surface. This is only an issue using mixes designed for very deep dives. Even then, not always.

He goes on...

First off, even deep air divers often use nitrox and or oxygen to accelerate and improve the efficiency of decompression. By the same token you could use a single gas on a trimix dive also. BTW that’s exactly what’s done in classes like the GUE recreational triox, the IANTD recreational trimix and the NAUI class who’s name I don’t remember.

When he refers to “fatal gas switches” he’s talking about mistakenly breathing a gas too deep or too shallow for it’s oxygen content causing oxygen toxicity or hypoxia respectively with the former being the more common mistake.

There have been lots of technical diving accidents due to improper gas switches but multiple gasses are necessitated by the amount of required decompression and not by the choice of the main diving gas. The same risk exists for the deep-air diver because there will most likely be more than one gas used for a dive of any significant depth or time.

More importantly breathing the wrong gas at the wrong depth is easily avoided by proper tank marking, correct gas switch procedures and sensible equipment configurations. We could write a book about just this one point but if you look at some of the instances of divers dying due to breathing the wrong gas you’ll see that often their procedures and their equipment were a total mess. I know that’s a little vague but I want to limit the length of the post. We can sure go into more detail later if you want.

He goes on to say that

Helium isn’t new at this point and we could say the same. It hasn’t been in use as long but it has certainly been used with far greater success. The current deep sport diving records were set using helium and the world record cave penetrations have been set using helium. Divers are going deeper, longer with less narcosis and feeling better afterwards than ever before and all using helium! Again we could write a book here so please comment and we’ll go into it more.

The other main point I have to comment on is what he has to say about gas management. I quote

Again I call total BS and I can’t believe that they put this trash in print. The rule of thirds originated in cave diving and the idea is to have twice the gas reserved for exit as you should need. That gas can be used to cover yourself for delays or gas loss or it can be used to get a buddy out in a worst case situation where the buddy suffers a total gas loss at maximum penetration. I will admit that if the diver is hosed and all narced on deep-air he is more likely to need it himself.

Also one-third is not reserved for ascent and decompression. This is a completely false statement. The idea is to have twice the gas needed to get back to the surface or the first gas switch. If part of that will be significant ascent or decompression time then a straight thirds calculation on the total supply isn’t good enough. In other words you’ll need to turn the dive before one-third the total gas is used if getting back to the entry point is critical. I believe the only one mistaken here is Michael Ange.

Read the article for yourself. The author contradicts himself on several points and provides no references at all.

For a quick list of references I’d refer you to “Basic Cave Diving a Blueprint for survival” by Sheck Exley, the IANTD “Technical Diver Encyclopedia” (and all the study references it contains), the NACD cave diving text “The Art of Safe Cave Diving” and the NSS cave diving manual. I’ll add a fourth set of agency texts and also recommend the GUE fundamentals, tech and cave texts.

Some books I’d recommend to get a feel for the history of some of this stuff would be “Caverns Measureless to Man” by Sheck Exley and the “Cave Divers” by...Burgess?...I don’t remember but I’ll look it up if any one needs it.

I have to get to work but I asked my wife to email a link to this thread to Rodale’s and invite them to comment.

 

[garyfotodiver]

About 28 hours after the Andrea Doria sank, two divers reached it. There is a famous photograph of one of them on the ship. What was his regulator? A Voit two-hose model. Was this dive made on air?

Something to think about.

 

[H2Andy]

ah... if i recall correctly, James Fox had to be helped up by Peter Gimble because he
(Fox) nearly passed out. By the time Gimble had Fox up to the surface, Fox was
barely conscious.

something to think about indeed

 

[bwerb]

About 28 hours after the Andrea Doria sank, two divers reached it. There is a famous photograph of one of them on the ship. What was his regulator? A Voit two-hose model. Was this dive made on air?

Something to think about.

Two brothers made an airplane out of canvas and wood in their bicycle shop...we've come a bit further since.

The first climbers of the North Wall of the Eiger did it in hobnail boots with hemp ropes wearing woolies.

I'll take progress for $2000 Alex.

 

[MikeFerrara]

OK Mike, here is what I mean by one-sided, on your part.

First, you have criticized him at every turn, without giving him any credit for his "few" valid points. For example, diving with only air is as a matter of conclusion "simpler" than diving with several mixes.

I see what you're saying but I left most of the article alone and quoted and argued selected points.

Second, you have steered clear of his intended point, the safe-ness of air, and instead you have steered onto all sorts of peripheral issues. I did not agree with his definition of the Rule of Thirds either, however that is only tangential to the main theme of the piece.

Yes, I did steer clear of the deep air issue because the article never really said much about what the subject depth was. I wouldn't really know where to start without some reference. Are we talking 100 ft?, 200ft? 300ft?

He does in fact, as you say, try to make a case for the safe-ness of deep air based on its long term historic use and the asserted lower level of fatalities of divers diving with air compared to technical mixes. But he does not document that, and neither do you document your rebuttal. Both of you are one-sided in your presentations.

No I didn't document it. I actually don't know what numbers are available for such a comparisson. I can point to a bunch of chamber studies but that doesn't really predict how things will shake out in the water.

If you read his comments about the complexity of trimix diving, carefully, you will see that he has cleverly stated the truth. He made it sound worse than it is, but what he says is true. You probably did not read it carefully enough.

You're right. What he said, was more misleading than untrue (leading you to believe that a trimix dive would always require more gasses than an air dive and that switching gasses is where the danger is)

I do not see any self-contradiction by the author. On the contrary, he is very consistent about repeating his arguments in favor of air diving as being more simple than trimix diving. What he does not do is address the other side of the issue, which you do not do either. That is my point, about one-sidedness.

The contradiction I was refering to were in the section titled "Avoiding Narcosis"

After talking about the simplicity of deep air diving earlier he states that on a dive that involve complex tasks like navigating a wreck or long linear swims usually involve more impairment than simple bounce dives.

Again I'm not sure what depth we're talking about but I don't usually consider a liear swim a complex task. Maybe if you're too deep on air it is. LOL What is a simple bounce dive? Is it where you just bounce down to say that you hit the depth and then go right back up before you get in trouble? I agree that I could be VERY impaired and pull that off but that's because you don't have to be very sharp if you don't have to do anything other than breath. In that one paragraph I think he made a pretty good case against.

But anyway I left all that out of my original post.

I do believe the article needed more work, before going to press. And I think your response would have been more effective if you had toned down your counter attack somewhat.

Of the two of you, Mike, YOU are more correct than the author, in my opinion. But you each could have done more to represent the other point of view in your response.

I won't disagree there. I realize that he wasn't trying to teach a trimix class with the article so something had to be left out.

Still, I'm looking foreward to asking him what the goal of the article was if he joins us around the first of the month like he said he'd try to do.

 

[Angelo Farina]

I did not read that article, so what follows is just a comment to what you wrote in the original post.
European agencies such as Cmas and Bsac consider deep air dives with "light deco" as fully recreational dives.
Each agency has its own max depth limits for recreational deep air.
My fully recreational Cmas *** certification is for 50m max with deco, in air.
Some other agencies allow for slightly more depth.
Such dives are short and simple, just slightly longer than a bounce dive.
Needing some deco stop, you need it to be properly planned, equipped and executed, which makes it safer than a dive to the same depth done "riding the NDL" and not employing proper redundant equipment, gas planning and logistic support for deco stops.
The accident records of Bsac proof that these recreational divers are exposed to a truly minimal and acceptable risk (because they perform this type of dives only after years of training, and operating in a no-profit club environment, which provides continuous training and very little complacency).
I understand that people operating in a different for-profit, shop-based environment, and where training does not include deep air with deco, can see it scary and difficult to understand...