Weather Based Scoring

The last few decades have seen the emergence and refinement of technical approaches to predicting the performance of racing sailboats. The modern velocity prediction program (VPP) has proven to have a high degree of accuracy in comparing the boat speed potentials of a wide variety of designs in essentially all relevant combinations of wind speed and angle. VPPs are therefore of extraordinary utility in providing ratings / time allowances between boats while racing. The challenge of VPP based handicapping has been, and continues to be, how to make best use of that technical precision and resolution. The value of having accurate speed differences between boats at any combination of wind speed and wind angle is greatly diminished when a race authority does not know what those combinations will be during their race. It has been common practice to make the choice of rating and time allowances, which themselves are based on a table of wind speed and wind angle combinations, well in advance of the race start date. Those choices have generally been based on either historical weather patterns associated with a specific race, or on the belief that the weather conditions are so unpredictable that organizers opt for a generic mix that is logically defensible. In fact rating certificates build in the ability to use a generic mix by making available all purpose single number scoring numbers on the certificate itself such as GPH. Over the last 15+ years weather forecasting, and the archiving of the results from those forecast models in digital format, in conjunction with tools such as optimal routing, have provided a compelling alternative. The routing of representative fleets through GRIB files of historical wind and ocean current provides valuable insight into the actual environmental conditions that boats experience and has led to more accurate estimates for race scoring. Weather forecasts themselves have become sufficiently accurate to enable race authorities to calculate ratings that are tuned specifically to those forecasts and then distribute them to competitors shortly before racing starts. This approach can greatly mitigate the perceived “unfairness” of variable weather patterns that treat different boats differently and thereby provide a better “racing experience” for those competitors. The authors present a review of how weather-based scoring is being used, some recent results, and comments on some of the pros and cons of this approach.