Distance vs. Time
Time on Time vs. Time on Distance
Time on Distance
The PHRF rating is provided as a "time on distance" allowance. The difference between two ratings is the number of seconds owed for each mile of the course. Lower PHRF scores equate to faster boats. For example, if a faster boat with a PHRF rating of 150 sails against a slower boat with a PHRF rating of 182, then the faster boat "owes" the slower boat 32 seconds for each nautical mile of the course. For a 4 mile course, the 150 rated boat must finish ahead by at least 128 seconds in order to be the winner.
Time on Time
Time on time corrections are being implemented by many clubs in our area. Because of the nature of the PHRF adjustment using time on distance, if boats race in wind conditions significantly different than the average, the allowances may be exaggerated or insufficient. For example, in light airs, all boats travel more slowly, a race over a given distance takes longer and the time separation between boats becomes greater, whereas in high winds all boats travel faster and races become compressed.
Time on Time gives slower boats more allowance in slower races and less in faster races. For these reasons, time on time corrections may work better over a wider range of conditions. A further benefit is that the distance of the race is not used in the calculation. Therefore exact placement of marks and measurement of course length is unnecessary.