For a recreational nitrox course with more meat to it the TDI, NAUI, or SEI Nitrox courses are all about the same. I can see all sides of the argument for certing to 100% for all nitrox classes. Normally the recreational courses, if you will, are for those who may want to just dive to 40% but still understand the math and science behind the formulas. Those that don't include this stuff, and really for up to 40% may not need it, except when it encourages a lack of attention to things like the CNS clock, PO2 loading beyond what your computer tells you based on the individual, and an attitude of "set the computer and go have fun" type fluff.
I have spoken to a number of people that are nitrox certified, supposedly, who still don't understand why 28% or 30% is better than 32% for certain dives. Not just for depth but for personal physiology reasons. Myself I don't mix or plan for 1.4/1.6 on deco. I prefer 1.3/1.5.
When I was nitrox certified through PADI in 2004 my course covered all the formulas, I had to calculate EAD, Best Mix, MOD, and we actually did a little with blending. But that was, I am sure, my instructor. I have no problem with people doing the on line portion for the TDI class and then coming to me to get the practical stuff done. Have certed a couple divers that way and it's nice to only have to spend 1 1/2 hours instead of three or four verifying they understand the material. I'm not going to take anyone's computer print out as proof they do. It's less money 35 vs 145 but it is also usually done to qualify for the HOG reg course.
It was a bit of an eye opener for me to see that when I crossed over to SDI/TDI the SEI nitrox class I was teaching covered everything in the Nitrox and Adv Nitrox classes even though one was supposedly good to 40 and the other to 100. The SEI one by the way is for mixes to 40%. As for deco on back gas that is covered in the SEI OW class using the Navy tables.
Where I have seen the difference in the TDI Nitrox and Adv Nitrox classes is in the people taking them. I teach AN in conjunction with DP. Been asked about AN alone but I kind of discouraged that as the diver did not really want to do deco. They just wanted to speed up getting rid of residual O2 when diving air by switching to O2 at the safety stop. One reason was they did not want to dedicate tanks to nitrox but were ok with having a 30 or 40 with O2 in it slung as a pony. Did not think that was such a good idea. Maybe I was wrong but it just seemed to up the risk factor if they had a problem with the main tank at 100 feet and jumped on the O2 out of habit.
With AN there really is not that much more content than the TDI Nitrox class except that it is now put into context with actual staged decompression and that, to me, is where the whole thing changes. As well as adding dives using up to 100%. Adds a new level of risk and while up to 40% is not going to be much of an issue if someone's buoyancy is a little off, with 100% or multiple deco gasses, it becomes much more important that buoyancy and trim skills are spot on.
I don't see it as a money grab in the same vein as manatee wrangler or pool diver. I see it as options for those who want the additional knowledge and skills to suit their diving styles and interests. Not everyone is a dive god with all the knowledge there is about it gained in a few short years. Some take longer than others and need the steps broken down a little. Not everyone is an engineer that can do complex math in their head. There are those who are just as intelligent, but in other ways, for whom math is a challenge and so coupling that with the proper mindset also needs to be introduced in stages.
Being over 55, with a lot of other things going on, my mind does not work the same as it did 20 or 30 years ago. I need to slow down on some things and put them on paper to see the relationships. If someone is a genius good for them. They should however not use it to belittle others and the routes that they may need to take in order to reach the same destination.
