Q: What is the difference between Time on Distance (ToD) and Time on Time (ToT) scoring?

A: The ratings used in the familiar ToD approach to scoring follow directly from the science of sailing yacht performance prediction, in that ToD ratings  reflect the time that it takes for rated boats to sail a given distance in certain conditions. These days, ToD ratings are typically expressed in seconds per mile, and corrected times (CT’s) are calculated by subtracting a time allowance (TA) for each boat relative to an arbitrary scratch boat (TA=delta rating x course length) from their elapsed time (ET).  Calculated this way, CT’s for each boat are lower than their ET’s, and the boat with the lowest CT is the winner.

ToT scoring is quite different, in that instead of handicaps targeting the distance sailed as in ToD, the ToT handicaps target the time taken to complete the course.  To do this, a Time Correction Factor (TCF) is established for each boat based on a conversion from her ToD handicap.  TCF’s are typically targeted to have a value of 1.000 for a mythical boat that represents a fleet ‘median’.  Boats that are faster than the median have TCF’s greater than 1.000, and slower boats have TCF’s less than 1.000.  A boat’s corrected time is calculated by multiplying her elapsed time by her TCF, so fast boats have CT’s that are greater than their ET’s.  The boat with the lowest CT is the winner, just as in ToD scoring.