Nitrox, MOD, and Suunto Stinger.....

[CA Wreck Diver]

After passing my IANTD Nitrox course I was playing with my Suunto Stinger (which is Nitrox compatible) and I discovered that it will tell you the MOD for 32% with a PPo2 of 1.6 is only 127 fsw. All tables I have seen and the math I have done give a 32% mix with a PPo2 of 1.6 a MOD of 132. I know this is not a big difference, but I am wondering why the difference in MOD. Is this a safety area Suunto built into the computer? Any ideas or info?

 

[DiverDanC1]

If you use PADI's table the PPo2 of 1.6 is about 130 ft. Suunto probably doesn't want people taking dangerous chances by playing it so close. So the extra five feet or so is a safety feature for those that don't dive a plan but rather dive their computer.

 

[RichLockyer]

This is a well-known "feature" of all Suunto nitrox computers.

Think about it... the computer is doing what you were instructed to do.

How many times has your blender nailed 32% dead-on? Never?
Weren't you taught to round down for NDL purposes, and to round up for MOD purposes?

That's what the computer does. If you get a tank of 32.3, you can only put in 32%. The Suunto adds 1% for it's MOD calculation.


Oh... and do yourself a favor and do NOT dive the Suunto to 1.6. As soon as you hit 1.4, it will run the CNS graph to max in 15 minutes... faster if you go deeper. Besides... 1.6 is simply not safe for anything but a deco hang. If you're planning to venture deeper than 107, drop your mixture to 27 or 28% to keep the 1.4 MOD to 130.