Wouter,

I am sure you are aware of the portsmouth handicap system controlled and administered by US Sailing. Please refer to the US Sailing website to answer your question on how a rating is determined. They provide a detailed explaination of their system and adjustments to that system.

You appear to have made an error in your calculations. According to the published results, the boat you question sailed with a rating of 64.1, not 64.4 as you used to calculate the base number. Again, please refer to the US Sailing's portsmouth ratings to verify the base rating.

The boats performance through the years seems to speak for itself. I believe any issues about handicap rating should be directed at the handicap system itself, rather than individual boats sailing within that system.

Regards,
FP