There are several different prescribed sail area measurement systems and some classes had their own that varied. Sails can be designed to work within a particular system to have a little more real world sail area and still measure in. The measurements are all just an approximation of area taken at a few reasonably practical points. The sail area generated from the software used to design a sail will be different from a sail that's measured manually...and to measure in to any rule, the sail needs to be measured per the prescribed method. I seem to remember that F18 originally had a slightly simpler, self prescribed, sail measurement procedure and that they adopted the ISAF method when they become a fully fledged ISAF class. Both systems would come up with a different number for any given sail and neither would match the software number. A sail measurer is usually listed/recognized with the class they're measuring for and some classes require some level of sailing organization certification to be a measurer. You may also be recognized by one class and not another. In order for Glaser to measure a class sail, he has to learn the measurement method (assuming SCHRS is different) and actually perform the measurement...if it's not a system that he (or Pease) will use often enough, I can see why he would have chosen to not offer the service.

That said, the Nacra 20 sails? I can probably guess why nobody would want to get involved with those numbers! Political football that probably has a pattern of variation in a distinct path...but I can only guess.

(BTW, Bacho has been designing sails in various software packages from low budget to high end and I've helped produce a few - I was also an F18 sail measurer for a while).