Some Comments after Nitrox Certification

[H2Andy]

As a new diver, how concerned should I be? Am I putting myself at a much greater risk than I believe by following the published guidelines of my training agency? If so, what, if anything, can I do to mitigate the risks, short of not diving at all?

i think the problem comes when there is a disconnect between what you have
purchased and what you think you have purchased.

if you are aware that you have purchased a bare-bones introduction to diving
at the Open Water stage, you should be ok.

that would dictate that you seek further training and more education and not rely
solely on what you have learned in Open Water training, which is, unfortnately,
what most people do.

they never really get the most out of diving because their training and skills are
severely lacking.

 

[TSandM]

they never really get the most out of diving because their training and skills are
severely lacking.

There is a big difference, though, between the above statement and whether somebody knows enough to remain safe underwater if they follow their training.

BTW, I agree with that quotation.

 

[OHGoDive]

that would dictate that you seek further training and more education and not rely
solely on what you have learned in Open Water training, which is, unfortnately,
what most people do.

Well, certainly seems reasonable to me. It's not that the courses, or the ways that they are taught, are inadequate, just that they are not comprehensive. As long as someone doesn't get out in front of their training/education, they're probably going to be ok, the courses they've taken have accomplished exactly what they were designed to do.

It's a complex sport, there is a lot to learn, both theoretically and practically. That's one of the joys for me so far. There will always be more to learn, but I feel pretty good about what I've been exposed to so far, enough so to continue to educate myself both about what I've already been taught and about what else I might want to learn down the road.

Perhaps I'm the exception, but it's nice to know I have a lot of choices. Thanks.

 

[logos]

I think what you're talking about is the difference between training and education. Diving is something that seems to fall under training.

Training can be great because it is a fast way to teach a skill. The downside is that you have to use set in stone rules or protocols or similar rigid structures. Training dosent have much flexibility because you dont know all of the relevant variables and complexities.

Education takes a lot longer and dosent necessarily teach a specific skill. The major advantage is that you can adapt and be flexible with what you know. It generally involves learning a great deal about things that probably are of little day to day practical relivance to performing a skill like diving.

 

[H2Andy]

i like logos' distinction ...

it's nice to know not just "what" to do, but "why" you are doing it. that way,
if "what" to do becomes unavailable, you can pick something else to do that
will get you what you want, since you know the "why."

TS&M: i generally agree with you ... but ... i've seen several divers follow the
"letter" of their training and not understand the "why." the classic example
was a diver in the Cayman Islands who shot to the surface from 70 feet
because she only had 500psi in her tank and her instructor told her always to
surface with 500 psi. she just rocketed to the surface, passing a number
of divers who had plenty of gas.

she was in my boat, and we gave her O2 on the ride in, and she was ok ... but
dang... talk about not seeing the forest for the trees

 

[cerich]

when I was an instructor in Cayman I saw this so often I briefd that I wanted them back to their safety stop with 500psi and to do their safety stop on each dive unless they has less than 300 psi

 

[Charlie99]

The PADI nitrox class covered the essentials and nothing more. This has the advantage of repetition and emphasis on what's important. The drawback, as the original poster noted, is failure to further educate those that desire better understanding.

Fortunately, those that wish to further their education are more often than not self-motivated learners.

While I might quibble with certain details that were omitted from the PADI Nitrox course, and the course was not optimal for me, I agree with the overall philosophy of concentrating on the essentials.

A possible solution is the greater use of sidebars, appendices, or other supplemental material.

 

[Charlie99]

Now I'll post the alternate version ---- how PADI's course is a joke!

I had a one-on-one nitrox course, and several times I had to explain to the instructor how I calculating things because my formulae didn't match up with the book. I was working from the basics of total pressure and % of gases, using formulae that matched up with the concept rather than using the more calculator friendly, but not so obvious, equation that were in the PADI book.

The original poster mentioned the EAD equation. I clearly remember reverse engineering that equation to figure out what it was doing, and then suddenly exclaiming something like OH! They mean Equivalant Air NITROGEN Depth (the equation figures out depths where ppN2 are the same). The instructor kind of goes Huh? And when I explained the basis of EAD it was the 1st time she had ever heard it explained that way.

Clearly, some further in depth explanations are called for, at least for instructors.

 

[alo100]

I wanted to make some comments about the inadequacy of diving training material after having recently been Nitrox certified. In fact, what spurred me on to start this thread was reading the thread on 'tables vs. computers'. Let me say that my statements are in no way intended as a response to any particular person or post in that thread. Also, my statements shouldn't be construed as thinly veiled attacks against any particular agency; I was PADI-certified and I don't regret having done so.

One of the common themes that I ran into while reading the aforementioned thread was the idea of adapting the training side of diving to the eventual usage by the trainees (and, of course, I'm paraphrasing/condensing here). So, one justification provided for under-emphasizing the mathematical and generally theoretical foundations of diving is that a considerable portion of the people who get certified are simply not interested and will never employ and remember those principles beyond the classroom.

I'm not trying to start that debate anew, just to approach the subject from a different angle. Consider my statements as the viewpoint of the person who approaches the subject from the exact opposite direction of the above-mentioned stereotype, i.e. the student who wants to learn as much as possible during training rather than flush his brain soon after the class is over.

Coming from that perspective, the training material that i was exposed to (NAUI OW, PADI OW, AOW and Nitrox) are sorely lacking in providing in-depth knowledge to students who are willing to go beyond the basics. There is no clearly articulated justification for this. Nitrox was the one that pushed me over the edge; here is a 'specialty' subject where the manual is as simplistic as can be. Clearly, the authors of this manuscript went to great pains to do what we generally refer to as 'dumbing-down'.

Let me give a brief example from the most glaring section in the manual entitled "Simple Calculator Stuff: Using Formulas". One paragraph states that using the formulas is simply a matter of plugging in variables. That is of course true of most formulas! However, as an academic (and an educator at a major US university) I cannot imagine any college-level course where the instruction is "learn to plug in formulas, never mind what they mean"! Why exactly is EAD=((1-02%)x(D+33)/79)-33? Don't others want to know how we arrive to that formula, how the variables interact, the theoretical premises behind them? Aren't there publications in peer-reviewed journals where these concepts are adequately explained, and if so, why aren't they cited even solely for reference's sake?

Maybe this truly has to do with PADI's manuals, in which case I am actually agency-bashing without knowing it. But I suspect that the phenomenon is more widespread than that. In any case, I will finish my diatribe by asking for some suggestions in further reading to actually fill those gaps. Also, I'd like to point out that I learned more about Nitrox here on Scubaboard than I did from reading the manual!

I am a creational diver and just passed by to see this formula, just wondered if anybody can show me the derive of this? Thanks!

Dalton's law of mole fraction.

P(total) = Pi/mi

Where Pi is the i-th partial pressure.
mi is the mole fraction of gas i among other gases, say, in this case the tank. So, Avogadro's Law said the volume of gas is proportional to the amount of gas in mole and is the same for all gas, indepent of size or mass of the molecules. So, the value 0.79, fraction for N2 in air, for example, can still be used here for the mole ratio. Others like Ideal gas conditions etc.

True for all depth and assume ideal gas conditions.

P(total)@1 is P(total) at depth1 for a certain tank.
Pi@1 partial pressure at depth1 for the same tank
m1: mole ratio 1 e.g. N2 in depth 1, its mole fraction in tank
m2: mole ratio 2 N2 in depth 2...
Unit: depth in meter and pressure in atm (atmospheric pressure)

P(total)@1 = Pi@1/m1 ........ (1)
P(total)@2 = Pi@2/m2 ........ (2)

A typical EAD formula looks like this:
Assume metric scale:
((EAD/10) + 1) / ((D/10) + 1) = FN2/0.79

Assume every 10 meter decend in depth in sea water, the pressure would increase 1 atm, and the "+ 1" is the 1 atm at sea level.

where EAD is the equivalent depth for air in meter. D
is the desired depth in meter and FN2 is the desired
fracton of N2.
Compare to this, try to use (1) and (2) to derive
the same formula

(1)/(2):
P(total)@1 / P(total)@2 = (Pi@1/Pi@2) x (m2/m1)
Let depth 1 = EAD, depth 2 is the desired depth
Let D be the desired depth, and as usual use N2 = 0.79 as in air.

((EAD/10) + 1) / ((D/10) + 1)
= (Pi@EAD / Pi@D) x (FN2/0.79)

The 2 formulas are not necessarily equal unless
Pi@EAD = Pi@D ????

Which step did I do wrong?

Thanks!

 

[Kev's First Mate]

As a new diver, how concerned should I be? Am I putting myself at a much greater risk than I believe by following the published guidelines of my training agency? If so, what, if anything, can I do to mitigate the risks, short of not diving at all?

You wouldn't happen to be an auditor would you? Sounds just like an auditor to me, no offense ("mitigate the risks").