08 entrants and PCRs
I've gotten a couple of inquiries about the PCR numbers for the racers, and why are they different from years past. Here to answer all your questions is Professor Antrim.
Professor....
Every year we have one more year of race history and I try to review the historical data to see if the formulas can be improved for a better fit. The last time I made such a change was for the 2004 race. Prior to 2004, the 375 factor in the LF formula was 345. Wildflower had a PCR of 216 in 2002. Calculated with the new formula that goes to 211, based on the numbers on his certificate at that time. With the current certificate, I see that the waterline has gone from 21.5 to 22, perhaps just a roundoff somewhere along the line. Also PHRF has gone from 186 to 183. With those two changes, PCR goes to 208.
BTW, it is possible that I will review the data again this year and propose another change. I would not call that likely to happen. If it does, I'll let you know.
Hope that helps!
Jim
Effective Length: L= LWL+0.35*(LOA-LWL)
Displacement/Length Ratio: DLR= (Disp/2240)/((L/100)^3)
Displacement/Length Factor (DLF):
For DLR less than 75, DLF = 0
For DLR from 75 to 150, DLF= (DLR-75)/3
For DLR from 150 to 200, DLF= 25+(DLR -150)*0.10
For DLR greater than 200, DLF = 30;
DLF is rounded up to the next larger integer.
Length Factor (LF):
LF = 0.5 * (375 – (3600/(1.34 * sqrt(L))) + PHRF)
If LF<0 then LF = 0
LF is rounded up to the next greater integer.
Rating: PCR = 486 + (PHRF + DLF - LF) * 0.95
I have posted an excel PCR calculator on the TransPac web site. It preforms this math magikly before your very eyes.
Synthia/Eyrie
Last edited by Eyrie; 05-09-2008 at 10:45 PM.
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