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 Guero 10-25-2011 05:57 PM

Help on PHRF Corrected Times

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Hi All!

I'm a Canadian expat in Mexico, Yucatan precisely, and doing Handicap racing in a very small club, usually led by a "clique". I've seen very inconsistent results in the last 2 years depending on who was in the lead. Last race winner was even switched from 144 to 147 HCP without any notice.

Anyway I'm not complaining, because I'm racing a non-racing boat against J/24's, Hughes Mk1 etc, however I'm usually doing very well and can keep my slug in the top 3. At the last race, I did something unusual, I was curious and asked for the formula that was used in the last race to calculate times and they were not even able to provide me with if it was ToT or ToD, nor the formula. That's weird.

What do you think of these results, do they make sense?

Winds for this race started at around 12 knots and on the finish line it was blowing around 20 knots.

Image is in attachment... Tiempo is Time taken, and Tiempo Corregido is the Corrected Time according to PHRF. My boat is Serenity. Thanks.

I appreciate all input and comments on clarification. I'm not sure why my club doesn't provide me with the formula that was used in that race. I've been racing for 2 years and never complained, but now that I'm curious and want to know what are the math, nobody gives them to me.

 CalypsoP35 10-25-2011 06:27 PM

You need to know the distance of the course. A 165 PHRF rated boat gets 18 seconds per mile over a boat with a 147 rating.

 blt2ski 10-25-2011 06:57 PM

One does not need the distance to do phrf, you would need the TOT factor, loking up a 165 it is 3416, 168 3401, so will do those two boats
165 6.0422 hrs x 3416 = 20640 secs
168 6.676 x 3401 = 22705

This is with a TOT factor for winds in the 0-15 range, There is another factor for 15-30 and 30 and above, or some such thing in the formula. the 168 boat a final corrected time of 6.3 hrs, you at 5.733 hrs. AGAIN, this is for the light wind. Being as you had heavy wind, the TOT factor could very well be what the correct time is.

here is the formula for the factors I uses
FORMULA = 650/(520 + T/D RATING) X 3600
found here
Non-Flying Sail Adjustments and the Time on Time Method | Pacific Handicap Racing Fleet

Now I have to remember if the 650 or 520 is a moving figure base on wind strength. I'm recalling the 650 would go to 550 and 450 for the mid and high wind range in TOT scoring. Which with the 450 figure, your times could be correct.

Example of one I figured a few years back. my final time was 3hrs 15 min. The above TOT put me at 3 hrs, mid wind tot 2:45, high wind 2:30, TOD about 2:25 for correct time in hrs and min. from memory

Marty

 paulk 10-25-2011 10:56 PM

If the club is using TOD, you do need to know the distance of the race to determine the correction amount, and then subtract it to get the corrected time. If TOT is used, the formula (see Marty's post above, if it is correct- I haven't checked) the distance doesn't matter. The handicap is based on how much time each boat took. Adjusting for the standard windspeed generally helps the slower boats to be more competitive.

Since you don't seem to be able to get anyone to give you answers on how the results are tabulated, it sounds like the club is using TOT, and probably a program like Sailwave (it's free, and really good) to calculate them. The RC plugs in each boat's name and rating at the beginning of the season, and then adds the start and finish times for the boats in each race. The program spits out the result, including series scores. Our racers are pleased that it also uploads to the club webpage, so they can get the results form their cellphones before they've even finished folding their sails.

 blt2ski 10-26-2011 01:12 PM

Here is a copy out of a local YC that also uses ToT for on of there regattas. ToT does work well in sailwave. Along with 10-20 other rules of different shapes and forms built in to the program.

Marty

13.2 Corrected times for PHRF Northwest handicap classes will be calculated using the Time on Time method as defined by PHRF Northwest. The “A Factor,” which does not impact result standings, will equal the “B Factor.” The "B Factor" for each race will be determined by the race committee, using the following criterion:
Conditions Approx. Average Winds B Factor
Light Winds 0 to 7 knots 650
Medium Winds 8 to 14 knots 550
Heavy Winds 15+ knots 480
The race committee's judgment in applying this criterion shall not be grounds for a request for redress. This changes RRS 62.1(a).

 n0w0rries 11-04-2011 10:26 PM

I made a fancy spreadsheet to figure it out, here's my equation:

Elapsed time - ((phrf rating*course length ) / 86400) = Corrected elapsed time

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