Nitrox Computer Setting

[TSandM]

None of the limits -- O2 toxicity or NDL -- is accurate enough to worry about a .5% discrepancy in Nitrox setting. NDLs can vary ten or twelve MINUTES between decompression models, and O2 toxicity is VERY poorly predictable, so whether you are at 1.4 or 1.43 really isn't likely to make a significant difference. Set your computer as you like, and don't push limits.

 

[John_B]

Yeah, I have Suunto's and that "feature" where they set back to 21 after some number of hours is pretty annoying. I can sort of see the conservative logic that led to that but it's still really annoying. If I'm on a liveaboard it usually doesn't have enough time to decide to reset itself, but land based where I might be out of the water longer it's always doing that.

And at that point you are screwed. None of your options are any good. You can "fly" the computer to the shorter air NDL (to make the computer happy), you can dive your plan and do the unneeded deco stops (to make the computer happy, assuming you have enough gas), or you can dive your plan and skip the unneeded deco stops and chance bending the computer (and maybe have it lock you out for 24 hours).

 

[Damselfish]

screwed is a little strong. As idiotic as the feature is, for one dive diving it as air is not a huge deal in the grand scheme of things for me. Some people do that on purpose. Tends to be over multiple dives where it really helps the most anyway. Just set it right for the next dive. It's when people aren't in Nitrox mode to begin with that they're really screwed.

I might push closer to the limits on the computer like I wouldn't do if I was really on air, it doesn't even need to go into deco. (For a little while I dove a Nitrox computer with my old air computer as backup, occasionally letting the air computer go a little into deco and doing the stops to make it happy. )

 

[ucfdiver]

1% either way BARELY matters when you factor in individual variances between people, and also the individual from day to day. These are built into the algorithms your computer is using.

 

[tclarke]

The fundamental issue I have is with the dive computer manufacturers not allowing you to enter a decimal point value. Let the computer do the interpolation ...

 

[ChuckP]

I'm a multideco user newbie for sure but running two same profile dives, 100' deep, 40 minutes with gas either 30% or 31% yields only a one minute difference in total run time, one minute extra at the last safety stop.

A decimal point may make you feel warm and fuzzy but that's about it.