The PHRF rating system is unique to each local area as it seeks to fairly rate boats that frequently compete against each other. The rating numbers are derived by observation of boat performance, with race results ultimately used as evidence.
In theory, when dissimilar boats frequently race against each other, their rating numbers are refined to provide fair racing. But do these observations change if the format for racing changes?
Do PHRF ratings derived from observations based on race results using the Time-on-Distance (ToD) method of scoring remain theoretically correct for races that use Time on Time (ToT) format? Christopher Cole doesn’t think so as he shares in WindCheck Magazine:
I’ve noticed that a lot of races recently seem to be using Time on Time (ToT) instead of Time on Distance (ToD) to correct time. I have a problem with that. ToT greatly favors the boats with higher PHRF ratings in every condition.
In a fairly average race in average conditions that went a very typical eleven miles in a quite common two and a half hours, we recently beat the second place boat by over ten minutes on actual elapsed time (00:10:28). Using the standard ToD formula, we would have won by 00:02:24 on corrected time. Under the ToT rule, however, in average conditions, we gave up another two minutes (00:10:04 total) and won by a mere 24 seconds!
I would think that in average conditions, a boat’s standard PHRF would be as close to fair as possible. But that is not the case. In fact, every commonly used “B factor” gives a significant advantage to boats with a higher PHRF!!
In light air under the ToT rule, with a B factor of 600, we would have gained only about half a minute and would have beaten the second place boat by about only one minute! And that’s in conditions that greatly favor the smaller boats! Again, under ToD, we would have won by about two and a half minutes, light air or not! – Full report
Editor’s note: If your mind is spinning with the acronyms, the US Sailing website has a power point presentation which explains the differences and offers how the ToT formula can get tweaked for each area … which throws another wrench into the process.