I do see Jake's point though, and Mike's, using a straight measurement only system doesn't chang the numbers for such things as a new type of mast (Carbon and/or wing type vs. older types) and newer hull shapes, etc.

But in order for Portsmouth to be accurate, I think we should be taking times at every major regatta, even if the fleets are not sailing together. And with GPS's it should be fairly easy for the RC to measure the distance from say, A to C mark(Ban the B!) hack the clock as the first Inter 20 rounds, then again when the first F 18, the the first A cat, etc. and get times for the fastest boat in each class going upwind, then down. Then you take that time and compare it to the existing P numbers to see how far and it what direction the numbers might be off.

You could do this at every Nationals, and at Tradewinds, and Spring Fever, etc, or any big regatta where the top tallent in each class is racing.

Just time the first boat in each class over the same distance, upwind and down, once during each race and then use several races to get a useful average time over that same course, then compare them to each other fleet.