Formula for survivabilty as function of water temperature?

Hello,

I am looking for a formula for the number of hours one can survive in the
water as a function of water temperature and the anti-exposure effectiveness
of the clothing worn (measured in "clo" units).

I have seen references to a fairly simple simple exponential formula (A to
the Bth power) where A and B are some combination of the water temperature,
the clo rating, and possibly some other simple constants.

Any help is much appreciated.


Wesley