Finding the best sailed PHRF boat

I have been ask to find which PHRF boat, scored Time on Distance, was sailed most perfectly.

Out of 40 PHRF boats competing in different fleets based upon the split of their PHRF rating, how can I find which boat was sailed the best by her crew? Can I find the perfect time for a boat then subtract her actual time and the boat with the smallest time would be the boat sailed most perfectly?