Originally Posted by

**Taz**
Hey guys

Just been reading your calculations.

I've just been on a weeks diving on the Dolphin in Egypt, driving it with the VR2 and O2 analyser.

I had similar calculations to you guys, but then noted that the calculations were, at times, wildly different on the VR2.

I came to the conclusion that although the calculations can be useful, as they are not accurate I would not drive the Dolphin without the O2 analyser and computer. Comparing the MOD on the O2% in the breathing bag via calculation and the actual O2% according to the calibrated computer, the results were often wildly different.

This struck me as a dangerous calculation which could quite easily lead to an O2 CNS situation (not good!).

No matter how good the calculations are, there are too many quickly changing variables on a dive for any calculation to be accurate.