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September 14, 2007

Nitrox certified

I was certified for Nitrox use on September 12, 2007 after completing the PADI course. Why PADI and not NAUI? Primarily because preparation includes a lot of work with dive tables, and once you become used to either the PADI or the NAUI method, it's difficult to change. The tables are, of course, based on the same principles, but just different enough to thoroughly confuse you. So I figured why add confusion to an already confusing thing like using dive tables?

It's interesting how those courses are conducted. You actually do all the studying beforehand with the coursebook in the crew pack. You also watch the DVD that covers the exact same material, but makes it all look nice and friendly. And you practice with the included dive tables. For the Nitrox class that's plastic dive tables for Nitrox with 32 and 36% of oxygen, and a table that shows equivalent air depth for mixtures with 30 to 40 percent oxygen. On the other side of that one is an Oxygen Partial Pressure table you use to calculate total allowable oxygen exposure for a day.

The course book is organized like the larger book for the initial PADI Open Water class. You read, you underline and you answer questions at the end of each chapter. The idea is not necessarily to memorize every word, but to grasp concepts and know where to look things up. The answers are always given, on the same page, in small print. At the end of each major section is a "knowledge review" that you fill out and sign. No answers given there. Studying and understanding all the materials takes some time, and then doing all the dive table examples takes some more. It's not necessarily very difficult, but it is important stuff that people from all walks of life need to understand before they go diving with Nitrox. Bottom line: you need to set aside several hours of concentrated worktime to prepare for the class.

The class itself was full. 12 people at least in a small but neat and well organized and equipped classroom. Our instructor was Rick Rowett, a PADI course director, which is as high as it gets in the PADI hierarchy, and also the manager of the Dolphin scuba store. And, as he later told us, a reverend. Rick was personable, knowledgeable and did a great job. The class essentially consisted of going through all questions of both Knowledge Review sections, with detailed explanations if someone had gotten it wrong or did not understand. A good approach, assuming everyone had indeed done their studies beforehand. Rick threw in a lot of explanations, advice, and anecdotes, making it all flow nicely and having great rapport with the class.

The second part of the Knowledge Review included several dive table questions, and we worked through each and every one of those in detail.

Once that was done, we signed a general liability release and were issued the final test that consisted of 25 multiple choice questions, including several that required the dive tables and a calculator. Those were not idiot questions and required some thinking. Once finished, you joined Rick in the next room where he demonstrated the use of an oxygen analyzer. You then got to use the analyzer yourself and entered the requisite data into a log book, just as you would when you get a Nitrox fill.

After everyone was finished and had done the hands-on with the oxygen analyzer, it was back to the classroom where we went over all the questions. Once again, Rick explained each answer and went into more detail if someone had gotten it wrong. I got 24 of 25 and stumbled over a trivial one. No big deal.

Thing is, unless you really, really goof, you can't fail. You no longer have to hand in the signed knowledge reviews that are part of the course book (and bound in). Apparently, you also cannot fail in the final test; at the bottom is a statement that says something like, "I have gone over the answers I got wrong and now understand the question and how to answer it properly," and then you sign that. And there are no dives involved. So you don't get to experience the difference between compressed air and Nitrox under the guidance of an instructor. No big deal, really, as Nitrox is becoming quite common.

I think I have mixed feelings on this. While Nitrox has been used for a hundred years or so, its use in recreational diving is relatively new. Initially and from what I am told, PADI and NAUI were quite opposed to it. Early course materials included true but rather discomforting statements like "you can die," and even the current course book has sort of a "not invented here" tone to it. It feels a bit like Nitrox is a subject that the certifying agencies were forced to include because the lure of longer bottom times (and feeling better after dives) were such that recreational divers simply wanted to do it.

If used improperly, Nitrox can be dangerous, but that goes for a lot of stuff in life. Anyone can walk into a car dealership and buy a 500-horsepower Corvette or Viper even though such vehicles can be vastly more dangerous than, say a Toyota Camry. There is no "Corvette" certification needed (actually, good thing PADI doesn't run the Department of Motor Vehicles...). So it comes down to common sense.

What makes it all a bit more confusing is dive computers. Sure, understanding the theory behind Nitrox use, and being able to figure out a problem on old-fashioned dive tables, is a good thing, but these days divers rely on dive computers. They may take a look at the maximum depth for their Nitrox mix, but then solely rely on what the dive computer says. And that's a big problem because dive computers are definitely not standardized. It can be next to impossible to even figure out if a dive computer can handle Nitrox unless you have the instructions at hand (and who does?) and that the instructions are halfway intelligible (they often aren't). So you take a class to learn Nitrox diving with dive tables, but then virtually everyone uses their dive computer and may not have a clue how to even set it to Nitrox. A definite weakness in the armor there.

In any case, I am hugely pleased that I finally have my Nitrox certification!

Posted by conradb212 at September 14, 2007 11:19 PM