Nitrox Class Without Tables or Math...OK?

[TCDiver1]

...... die thread die !!!!!!!!!!!! :shakehead

 

[Soggy]

What does that have to do with me putting in 32% and and a PO2 of 1.4 and it coming up with an incorrect MOD (107' vs the correct 111')? I am not trying to put fractional FO2s in it, the computer just has the formula plain incorrect, admittedly to the conservative side.

Soggy,

I was going to mention this a couple of days ago when you said something about the Vyper not knowing how to calculate MOD. On page 32 of the Vyper manual is the following warning:

"THE DIVE COMPUTER WILL NOT ACCEPT FRACTIONAL PERCENTAGE
VALUES OF OXYGEN CONCENTRATION. DO NOT ROUND UP
FRACTIONAL PERCENTAGES! For example, 31.8% oxygen should be
entered as 31%. Rounding up will cause nitrogen percentages to be understated
and will affect decompression calculations, which could result in
dive planning with an increased risk of decompression sickness. If there is
a desire to adjust the computer to provide more conservative calculations,
use the personal adjustment feature to affect decompression calculations
or reduce the PO2 setting to affect oxygen exposure tracking."

So, one can infer that the MOD for the Vyper is rounded up for the next whole percentage value. I verified this is indeed the case by doing the math.

Considering your occupation, background, knowledge, and natural curiosity, it really makes me wonder how thoroughly the "typical" diver goes through his/her owner's manual.

 

[H2Andy]

Andy, I don't care what car you own, the point is you need to learn how to drive.

if you want to drive with an automatic transmission and a V-4
engine that puts out 100 hp at best, your driving SKILLS don't have to be
as high as someone who wants to drive a Formula One race car.

if you want to drive your car to and from work in Florida, your driving SKILLS don't have to be as high as someone driving in hills with snow and ice in Alaska.

if you want to drive an Accord, your driving SKILLS don't have to be the same
for someone who wants to drive a fully-loaded semi truck cross-country.

they are all driving, but the SKILLS they need to do it safely depends on what
sort of driving they do.

the nature of their driving dictates what skills they need.

you can compare me to a Formula One driver, and my skills as a driver will
be pathetic. but is that a fair comparison? after all, i drive my putsy car back
and fort to work every day and don't get into accidents, and THAT's what i
need my driving skills for.

and yes, it would be wonderful if we all aspired to be Formula One drivers,
but thast's just not the real world, for various reasons: personal goals,
money, time contstaints, family obligations, nature of accessible driving
opportunities, etc.

 

[jiml]

No, I don't think it's a problem at all. I was merely pointing out where the discrepency was.

Edit -- (1.4/.33 -1)*33=107

 

[Scuba_Steve]

Get over it Andy, you need to learn how to drive/dive reasonably well. There is a base minimum level of skill that they fall far below.

We're not asking a licensed driver to hit the F1, we're asking him to understand how to not be a menance and danger to themselves or other people.

Let's try to get them this far. That's ALL we're saying.

Grade 5 math is all it takes, and we are dealing with adults.

If they're that dumb, you're right, I don't want them on the road, they will only kill themselves or others.

Fortunately most adults are more than intelligent enough, now all we need is the maturity to understand that you cannot breathe under water and you can get needlessly hurt doing this stuff, so maybe they should take this learning thing a little more seriously.

We've already seen, and will continue to see the daily disasters from doing it the way you feel is OK because, hey, they didn't need to learn this because they were only supposed to be driving those country roads, so how'd they get on the turnpike?

Some of us have better ideas since these others seem to not be working very well and the nonsense you propose is a dead end street sooner or later. So why bother doing it that way. It is a means to nothing.

<Bailing on this brain-dead thread> See soggy

 

[Soggy]

No, I don't think it's a problem at all. I was merely pointing out where the discrepency was.

Edit -- (1.4/.33 -1)*33=107

Yeah, but I'm talking about 32% nitrox, not 33% as you have in your formula, and while you may have inferred (it isn't explicit) that from the manual, it is rounding up a percentage (and appears to be the case), it doesn't change the fact that it is giving the wrong number.

(1.4/(.32-1))*33 = 111

 

[limeyx]

The biggest problem being here is that you actually think this is a real problem, which again is the type of reliance on nonsense vs. a reasonably solid understanding of what is truly going on.

I won't speak for Soggy, but I'd bet he, myself, and a whole lot of people would run the same schedule from EAN30 to 32 without worrying much about it. Unfortunately you feel that this line in the sand (from 31 to 32) has more of a value than it really does. We tend to not flirt with any PPO2 limits and can makes reasonable assumptions as they develop. There is no real decompression significance from 31 to 32% and that's how we treat it with much success.

This drive for decimal place accuracy may be nice on paper, but it needs to put into the real world.

Now you're definitely going to die. And take me with you! Whoever heard of diving 30% like 32% ?? How irresponsible.

 

[H2Andy]

There is a base minimum level of skill that they fall far below.

the base minimum level of skill is that needed to dive safely.
to that extent, i agree with you.

someone can dive safely with just a computer and no understanding of the tables
whatsoever.

think before you respond, now ... let's stay on topic

 

[Dragon2115]

Dragon - your key statement was "if you wish to step up to the ferrari"

not all divers want to do anything other than look at fish in 60 fsw. Doing so safely is far different from "getting the most out of it" - whatever that may be

That's fine, they should stick with air then. If they wish to step up to nitrox then they should be prepared to learn a few things, including some simple math so they have a basic understanding of what's going on. The class is already only a half day, less if you've done your homework and are even reasonably on your game. How much simpler does it have to be? It practically has training wheels on it now.

Let me ask you this, which do you think is better, teaching people about rock bottom pressure by giving them a spread sheet that's already been done for them and showing them how to look it up, or teaching them how to calculate it (and the necessary background equations like RMV etc) on their own so they know what's going on behind the spreadsheet?

 

[H2Andy]

If they wish to step up to nitrox then they should be
prepared to learn a few things, including some simple math so they have a basic
understanding of what's going on.

you can have a basic understanding of whats going on by understanding a few
definitions and figuring out how to obtain MOD with the computer and then
track NDL, MOD, and O2 levels with same computer.

show me where i need to know the math to understand Nitrox diving.