It would be nearly impossible to create a standard that could be applied to cancel a race. Wind speed, wave height, air temperature, water tempurature, current, etc. all play a factor. How do you create a universal standard? 20 knots in Boca Ciega Bay (protected flat water bay in Florida) in june is probably far different conditions than 20 knots in Hyannis (open ocean in the north east) in November!