Because our racing fleet is rather diverse, we use a handicapping system to compare boats' performance each other. A heavy, slow boat is given a time adjustment based on its expected performance so that it has a reasonable chance of beating a light, fast boat.
We use two ratings systems. For slower boats, we use PHRF, which is an economical ratings system based on some measurements and observed boat performance. For the faster boats, we use ORR, which is a considerably more involved system of measuring boats' weight and structure to create a computer model of the boats' expected performance.
Each boat gets its rating either in a "time correction factor" for ORR ranging from 0.8 to about 1.3 or so, or "seconds per mile" for PHRF ranging from 400 to 700 or so. To apply the rating, we take the boat's elapsed time, multiply it by its time correction factor, and compare the results with the lowest "corrected" time winning.
For boats with PHRF ratings, we use the "Downwind" PHRF rating and calculate a time correction factor using the formula TCF = 480/(PHRF-35).
Using the TCF is referred to as "Time on Time" scoring, and it's considered by many to be more equitable when the weather conditions are hard to predict. Previously, Pac Cup used a "Time on Distance" system where a boat would get a fixed allowance based on its rating and the course distance.
Here's an example of Time on Time scoring. Imagine three boats:
- Pokey Pete: tcf = .9
- Moderate Martha: tcf = 1.0
- Speedy Sam: tcf = 1.1
As we can see, if Moderate Martha wants to beat Pokey Pete, she'll not only have to finish sooner, but beat Pete by 10% to account for the different multiplier:
PP Elapsed time 90 minutes x .9 = 81 minutes corrected.
MM Elapsed time 85 minutes x 1 = 85 minutes corrected.
SS Elapsed time 80 minutes x 1.1 = 88 minutes corrected.
Even though PP finished behind the other two boats, the time was multiplied by a factor that resulted in a smaller corrected time. Winner!
Within each division, we use a single rating system: ORR or PHRF. For the Pac Cup overall, we get a "Certified" Downwind PHRF rating (meaning the boat was at least weighed) to compare the boats. The boats that did not obtain such a rating for one reason or another are not eligible for the Cup.
Okay, what about those "Standings" before boats have finished?
Glad you asked. Basically, we generate a prediction of the boats' finish times and use the same handicapping method as above.
Exactly how to forecast the finish is a topic of heated debate among the four or five people who spend any time outside the race thinking about it. For the 2018 Pacific Cup, the method we are using is: Determine their rate of progress toward the finish thus far, apply that rate to the distance to go, and use that resulting time to figure out their finish prediction.
This method more or less ignores sudden changes in speed for better or worse, and tends to make someone look temorarily bad for a tactical move like a big dive South to avoid unfavorable weather, but it DOES provide a fairly solid guess of finish order in the middle and long term. In addition, it is the same method used by our YB Tracker system, so we do not end up with inconsistent reports that some find troubling.