Some Comments after Nitrox Certification

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theatis

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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 don't often post in these type of threads but... I have been in and out of the tables v. computer thread too. My comment is that during my NITROX class, I not only learned the formulas, but what they mean and why. Even though I don't have to do any calculations, between my computer and the tools that came with the course (NAUI), I still calculate EAN & MOD. Just to keep in practice.

I too teach, at the graduate level (as an adjunct), those $140 text books have no more depth than the NAUI materials. IMHO, it is the instructor that makes the difference and transfers knowledge, not the text material. Lucky for me I had a great instructor who took the time to explain the why, not just the how.

JR
 
What exactly is wrong with dumbing down. It makes information much more accesible to a lot of people who could benefit from using Nitrox. If they told you that to calculate an equivalent air depth for any given nitrox mixture you must take the percentage of nitrogen inside the mixture and multiply it against the barometric nitrogen pressure exerted on you for a given depth, then subtract the barometric pressure that accounts for the air at the surface to arrive at the depth that is the equivalent for the depth you dived. Most people wouldn't have a clue about where to begin. But if they write (1-O2)X((D+33||10)/.79)-33 and then take people through those steps, as the manual does you'll learn it faster.

Has for how it works, well you have less nitrogen in a nitrox mix, the added oxygen limits your depth considerably with richer mixes and in order to calculate a depth for mixes that tables aren't around for, since partial pressure blending can be innaccurate and lead to either a slightly richer or leaner mix than the one desired being able to calculate the equivalent air depth is a formula that will allow you to determine this.

Your instructor should be able to help you with this and for what it's worth, I've found that PADI's manuals do a decent enough job of explaining information, if they didn't we would see a lot of dead divers every year.

EDIT - It's late and I'm diving tomorrow so if I've got something wrong about how the formula works please tell me.
 
I think what you are experiencing is an example of teaching to the least common denominator or teaching to the test. In such cases, inclusion of detailed supplemental information can derail less competent students (even if only because of confusion over what is required and what is not) and will slow the class because of time required of instructors to explain the "unnecessary" material to more interested students.

The suggestion, "As an excercise, the interested student can easily prove the given relations." is standard content in $140 textbooks.

Like THEATIS, I am usually interested in finding out all I can about whatever I do. I use forums like this and the web in general as a good starting point expand my knowledge. Also, many excellent diving books are available though sources as ordinary as amazon.com.

For a reasonable introduction look at
http://www.gasdiving.co.uk/pages/misc/Nitrox.htm
or for a more step-by step explanation

http://diverlink.com/modules.php?op=modload&name=Web_Links&file=index&req=viewlink&cid=45

or google "nitrox faq"

You dont state what area your adavanced degree is in but a knowledge of basic physics or chemistry will help.
 
You have to take into consideration that these texts are written for the “average” student. Also, NITROX is the only class (at least through NAUI) that requires NO SCUBA certification what-so-ever. Now, I don’t know what you would do with this card without an O/W “C” card -- you surely would not be able to dive with it, but, theoretically you can do it this way.

I’m not familiar with the PADI program, but I think the NAUI offering is pretty comprehensive. And, yes a good Instructor makes all the difference in the world irregardless of the agency. But, in reality, we need teach only a few important points to make a safe diver – things like, always check your % of O2 prior to accepting your tank, don’t exceed a certain depth or you’ll regret it – Big Time, make sure your tanks are O2 clean, etc. After taking this course, how many people are actually going to calculate partial pressures, MDT’s, etc. For the most part, they will get 32% or 36% and dive within the depth they are designed. Also, most of them will dive NITROX using air tables or an air computer.

It is similar in getting an O/W certification – don’t hold your breath, don’t come up too fast, don’t exceed your training, etc. A lot of other “stuff” is presented (all good) but, these “rules” are really pounded home and hopefully, remembered.

It is interesting, I have been reading some vintage SCUBA training manuals from the early sixties (just a few years after the start of certification agencies) except for the requirements of being militarily physically fit – push ups, runs of miles, chin ups, very little has changed. The “rules” that were emphasized then are the “rules” emphasized now. Considering that SCUBA diving has been getting safer over the years (comparing accidents as a ratio of amount of dives) something is being done right by our training agencies.

If you really want to see the whole “technical thing” come together, I suggest that eventually you take the NAUI Master Diver certification. This course is truly worthy of a college level SCUBA course.
 
I've said plenty about my opinions on what students need and deserve on the other 2 threads. Assuming that you really want an answer to your question about EAD, lets see if we can get that answered. If you don't then maybe some one else does so lets have some fun.

Lets look at some parts of the equation. (1- O2%) is an idiots way of saying FN2 or the fraction of nitrogen. ok? An example... If we're diving EAN32 then the fraction of nitrogen is 0.68 because the fraction of O2 is 0.32 and (1 - 0.32) = 0.68. They gotta add up to 1 or 100%. ok? The book would be correct if they said 1- FO2 or 100 - O2% but just stick with FN2. There isn't any reason to bring percent anything into it.

side note, the reason I said "idiot" is that 1 - O2% might be taken as 1 - 21 (for air) and air does not have a %N2 of -20 does it? Though you could use 100 - 21 to get 79. Don't do bouncing decimal points around all over the place when there isn't any reason to unless you just enjoy doing it.

(Depth + 33) is nothing more than the absolute pressure in (feet of sea water).

What is our question? The question is what depth using air 'EAD' would result in the same absolute nitrogen partial pressure that we have at a given depth 'D' with our nitrox mix that we're diving? Did I word that ok?....With less words...what depth would yield the same partialy pressure of nitrogen if we were using air. Better?

Lets write an equation to get started and see if you agree with it....The left side of the equal sign is the partial pressure of nitrogen in feet of sea water at depth 'D' with our nitrox. The right side of the equation is the partial pressure of nitrogen in feet of sea water with air (air has an FN2 of about 0.79) at some unknown depth (EAD).

(D + 33) X FN2 = (EAD + 33) 0.79.......that's a nice equality but we want EAD so solve for it. Rearranging to solve for EAD yields ((D + 33) FN2/0.79)-33 = EAD

I didn't show the algebra steps but all we did was to devide both sides by 0.79 and then subtract 33 from both sides to get EAD on one side of the equal sign by itself.

If something wasn't clear please say so and I'll try to write it differently.

There is no need to memorize formulas though you can if that's what you like. If you understand the question and the very most basic concepts of dive physics, the math takes care of itself.
 
Louma:
I’m not familiar with the PADI program, but I think the NAUI offering is pretty comprehensive. And, yes a good Instructor makes all the difference in the world irregardless of the agency. But, in reality, we need teach only a few important points to make a safe diver – things like, always check your % of O2 prior to accepting your tank, don’t exceed a certain depth or you’ll regret it – Big Time, make sure your tanks are O2 clean, etc. After taking this course, how many people are actually going to calculate partial pressures, MDT’s, etc. For the most part, they will get 32% or 36% and dive within the depth they are designed. Also, most of them will dive NITROX using air tables or an air computer.

Except that I've seen shops bank EAN30 and EAN34. I disagree that most divers will use an air computer or air tables. Today, many if not most computers are nitrox capable and even the PADI course supplies divers with EAN32 and EAN36 tables. If I remember right the old IANTD tables came in 28, 30, 32, 32, 34, 36...ect. the point is that a lot of divers are using these options.
It is similar in getting an O/W certification – don’t hold your breath, don’t come up too fast, don’t exceed your training, etc. A lot of other “stuff” is presented (all good) but, these “rules” are really pounded home and hopefully, remembered.

It is interesting, I have been reading some vintage SCUBA training manuals from the early sixties (just a few years after the start of certification agencies) except for the requirements of being militarily physically fit – push ups, runs of miles, chin ups, very little has changed. The “rules” that were emphasized then are the “rules” emphasized now. Considering that SCUBA diving has been getting safer over the years (comparing accidents as a ratio of amount of dives) something is being done right by our training agencies.

Bold added by me

BINGO! Very little has changed! Just as soon as they get around to really integrating the BC into training (like it was more than an afterthought) we might have some dandy classes and a few new divers who can really dive.
If you really want to see the whole “technical thing” come together, I suggest that eventually you take the NAUI Master Diver certification. This course is truly worthy of a college level SCUBA course.

Why should you have to take yet another course to learn the abc's of diving together with how it applies to something like nitrox?
 
if what you want is in-depth training and in-depth coverage of diving subjects,
you're looking in the wrong place. the certifying agencies have become mass-production entities, and their "classes" are designed to mass produce divers.

(i should say my only experience is with PADI, but from what i have read
about other agencies, this appers to be an across-the-board thing)

but you don't go to WalMart if you want to get a hand-painted oil portrait

there is a place for mass-produced dive education, but it's only the beginning.
divers have to take responsibility for their own education, know what it is
they got from the agencies, and seek the rest elsewehere. it's out there.

you do need to spend time and money finding it. but, as they say, you get what you pay for (sometimes, by a fluke, you get more ... but that's rare)

btw, i wouldn't blame the agencies. they are only responding to the market.
people like quick, cheap things, however unwise this may be in the long run.
 
My PADI instructor covered it in depth....there were only 4 in the classroom but he explained where all the formulas were derived from and how to use them, then we went into computers for an couple of hours.
 

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