Teejay, I think I understand your concern... but you need to understand just how Nitrox is actually used... and it is much simpler than you might think...
First is the fact that most divers using Nitrox have a Nitrox computer. All the tables and data are built into it. It could break... and you would have to abort that dive, but you could loose your tables... there really is not much difference.
Second, everywhere I have been, they use standard mixes, depending on the depths, but I would guess 32% is the most common. So now you have both a computer (with built in table) and a plastic table...
Third, You need to understand the scale and trends associated with the gas... not the exact down to the micrometer numbers.
If you are diving to 60 ft with 32%, do you need to worry about the MOD? The CNS total? With that gas at that depth, all you need to worry about is your no deco time... Clearly, if you are going deeper, if the mix is richer, you do, but both the computer and the tables can tell you when to be concerns.
For the record, in the last two years, the highest I have had my CNS level at the end of a dive, was using 36% for both dives... with the following details:
First dive...55 minutes @ a max depth of 84 ft..47 minute surface interval, followed by:
Second dive....85 minutes @ a max depth of 56 ft..
At that point, I had a CNS % of 38%, which is the highest I have ever been.... including 5- 8 dives per day with 32% in the dry tortuga's.
MODs don't require math...both tables and computers will show the value..but if you want to do the math... you will know the right answer before you start.
So what if they give you 33%.... or 37%. It is just not that hard to get the value (92 ft for the 37% @ 1.4) because 33 is a bit less that 32 and 37 is a bit less than 36%..
Now, if you want to push the envelop.. and dive exactly to 1.4.. or say 1.6... and you want to do lots of dives.. then you would need to spend a bit of time making sure everything is done correctly.
well, ya know... I did read the manual. I read it until I thought I understood it. Then I took the class. If reading the manual would bridge the deficiencies, if it would make me confident that I could calculate PPO and MOD without errrors, I wouldn't be so off EAN diving at this point.
EAN diving contains enough risk that it's uncomfortable for me, unless I am completely in mastery of the subject. Being an inland diver, it's rare that I have a reason to go deep enough to use nitrox. And my steel 120's give me 1.5-2 hours bottom time already, on plain air. The time when I would benefit from nitrox would be when i go on vacation and dive wrecks and such. And/or don't have my 120's with me. Vacation happens once or twice a year. And this is not often enough to remember how to calculate EAN dives, or even remember the formulas involved.
If you can use EAN32 like air but you set your computer for it, you aren't using it like air any more. And you are placing your complete trust in an electronic device which could fail. If you don't know where you are on the map of oxygen toxicity, what are you going to do if there is an incident and you have to change your plan on the fly? When i was in class, I frequently wondered if EAN divers took their tables with them underwater. If you accidentally stayed a little long or went a little deep, what do you do?
Yeah, I'm kinda put off EAN. I can easier deal with being bent or air embolism or most anything else other than having a convulsion underwater. I've seen enough and read enough to understand the risk of dying is real in this sport that I love. It just doesn't seem worth it to me, to increase that risk for an extra 10 minutes bottom time.
