Compilation of North American Portsmouth Numbers and Wind Dependent Handicap Factors
A Service for Sailors with online access provided by US Sailing The North American Portsmouth Yardstick for centerboard boats, multihulls, keelboats and offshore classes are posted here. The Yardstick is a widely used method of rating boats of different classes sailing the same courses and is used by clubs and fleets across the country. It is a time-on-time handicapping system derived from actual records boat classes with thoroughly documented ratings. Portsmouth Numbers are defined as the length of time boats would take to sail a common but unspecified distance. The formula is easy to use: CT (Corrected Time) = ET (Elapsed Time) X 100 / HC (Handicap) Annual changes in ratings are modest. The elapsed time for each boat in a race is measured against the primary and secondary yardstick classes in the race and a handicap calculated for each boat. These are stored in the database by Beaufort number. When there is new data, the previous ratings are adjusted by 25% of the difference between the old ratings and new history.