Hi Robert,

I have been doing some testing, as you have seen from emails on the mail list and have looked at the existing Subsurface code in divelist.c.

With respect to the calculation of CNS%, your and my calculations are identical EXCEPT that, for a specific PO2, you only use the next-lower tabulated maximum time and do not interpolate to provide for a PO2 value that is intermediate between two tabulated max-time values (line 214 in divelist.c). We use the same table originating from the NOAA Diving Manual and I think that is safe. Therefore the Subsurface CNS% values are slightly conservative.

With respect to the calculation of OTUs, you use an analogous but different formula from the one provided in the Baker document. At this stage I would not say that the formula in the existing code (line 165 in divelist.c) is better or worse than that of the Baker document (taking into account other bugs in the Baker document). But do you have any idea where the formula in divelist.c comes from? I would like to do more reading around the issue to come to a sensible conclusion about these differences.

Kind regards,


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