Apparently there had been a discrepancy between our performance calculation and the official one of the Pacific Cup Race Committee, which, with a little bit of helping from our end, was resolved in our favor ;-).

One problem is that there is really only one criterion to judge performance: crossing the finish line! Everything else is undefined. Nevertheless, we all want to know where we stand in relation to the competitors while still racing, and are looking for some formula to do that. In addition, in a race like the PacCup, where boats start at different times and with quite different technical properties (long vs. short, light vs. heavy, etc), the comparison becomes even more complicated.

Once a boat has crossed the finish line, its time will be corrected using the PCR rating of the boat. Cirrus' PCR is 607 seconds per nautical mile. With a distance of 2070 nm to go, the correction will be 607 * 2070 = 14.54 days. Or in other words, the expectation is that it would take Cirrus 14.54 days if properly sailed (an average speed of 5.93 knots). If sailed like that, the corrected time would then be exactly zero. The fastest boat in this year's fleet is Free Range Chicken with a PCR of 454 (10.88 days). The final ranking of the boats is then made by the corrected time of each boat.

So far so good, but how do you do it for the positions in between? Taking simply the distance traveled does neither account for the PCR nor for the late starters. You need a performance criterion, which is independent of both, and involves a time, so that you can correct for PCR. I have chosen VMG, corrected as described below. VMG is "velocity made good", i.e. the speed in strict direction towards the finish line, measured from the start as

VMG [kn] = ((Great Circle Distance from Start-to-Finish [nm]) - (Distance-to-go via Great Circle [nm])) / (Elapsed Time [h])

This VMG is then corrected with the PCR, using Cirrus' PCR as reference (to avoid the mathematical problem of having to divide by zero if a boat would go exactly at its rated speed, or the corrected speed becoming negative if going even faster than rated)

VMG corr [kn] = VMG [kn] * (1 - 1 / ( VMG [kn] * (PCR - PCR ref)[h / nm]))

Such a VMG corr does properly account for different ratings and late starters, and a ranking based on it would converge into final standings.

It should, however, be clearly understood that such a measure does not take into account any strategic advantages or disadvantages from e.g. going south or not doing it! Ultimately, going through the finish line is the only thing which counts.

For the Geeks among you:
Our performance tracking and ranking software aboard is based on HTML/PHP pages served by an HP dv5000 laptop running a Linux Kubuntu 6.06 (Dapper Drake)version of Apache 2.0 webserver with PHP extensions, gd library, jpgraph library extended with a Mercator projection class to allow plotting of navigational charts, and SQLite database. Works beautifully!

Ulli

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