Skipper Handicaps : How they work .
(1) Why do we use skipper handicaps anyway
The aim of handicapping is to find out which skipper has improved the
most on time relative to the others he is racing against. And thus
reward him or her accordingly even if he or she didn't win the actual
race. Over the entire sailing season we want to find out who has
improved most often, on average, against the others.
Handicaps are adjusted each time a boat races. Every boat that races has
its elapsed time from start to the finish recorded.
Say we have three boats racing with elapsed times as follows:
1st Red, 27 minutes 30 seconds = 27 + 30/60 minutes = 27.50 minutes
2nd Blue, 28 minutes 20 seconds = 28 + 20/60 minutes = 28.33 minutes
3rd Yellow, 29 minutes 40 seconds = 29 + 40/60 minutes = 29.66 minutes
And, given that Red's initial skipper handicap rating is, for example,
0.978, Blue's is 0.954 and Yellow 0.874.
(2) To calculate handicap positions
The following formula is used to determine the corrected time:
Corrected Time (C) = Elapsed Time (E) * Handicap Rating (R)
Red C = 27.50 * 0.978 = 26.895 minutes
Blue C = 28.33 * 0.954 = 27.029 minutes
Yellow C = 29.66 * 0.874 = 25.929 minutes
Ranking the boats in order of corrected time Yellow would finish 1st on
handicap, Red 2nd and Blue 3rd. Thus, Yellow would score 1 point, Red 2
points and Blue 3, using the usual low point scoring system.
(3) To calculate ratings for the next race
We solve for R by using the winner's time, Red, as the desired corrected
time in the formula for Blue as follows:
27.50 = 28.33 * R
R= 27.50/28.33
R= 0.971
Similarly for Yellow
R = 27.50/29.66
R = 0.927
Red, the winner, will get a rating of 1 (R=27.50/27.50).
Handicap ratings will thus only range between 0 and 1.
(4) Weight the Rating to prevent huge fluctuations
These new values could be used for the next race. However, it would be
unfair if Red had won by a fluke chance. Also, we need to average out
the wind conditions as Red might only do well in a strong wind. We thus
weight the old handicap rating with the new one in the ratio 4:1. So
Red's new handicap would be (4 x 0.978 + 1 x 1.000)/5 = 0.982, Blue
would be (4 x 0.954 + 1 x 0.971)/5 = 0.957, and for Yellow = (4 x 0.874
+ 1 x 0.927)/5 = 0.885.
(5) Using the new weighted Rating for the next race
We use this weighted value of R for the next race to calculate the
corrected time, as we did in paragraph (2) above e.g. if the elapsed
times were 1st Blue in 31.50 minutes, 2nd Red 31.75 minutes and if 3rd
Yellow finished in 32.10 minutes.
Red C = 31.75 * 0.982 = 31.18 minutes
Blue C = 31.50 * 0.957 = 31.15 minutes
Yellow C = 32.10 * 0.885 = 28.41 minutes
Ranking in order of corrected time Yellow would finish 1st on handicap,
Blue 2nd and Red 3rd. Finally, Yellow would score 1 point, Blue 2 points
and Red 3, using the low point scoring system. Final positions in the
series on handicap would be worked out using the total of these scores.
The sailing instructions will determine the number of allowable
discards.
(6) Calculating new R values
We use the times from this race now to calculate new values for R as we
did in paragraph (3) above:
Red R = 31.50/31.75 = 0.992
Blue R = 31.50/31.50 = 1.000
Yellow R = 31.50/32.10 = 0.981
These are weighted with the 'old' ratings as we did in paragraph (4) so
that for the next race
Red R = (4 x 0.982 + 1 x 0.992)/5 = 0.984
Blue R = (4 x 0.957 + 1 x 1.000)/5 = 0.966
Yellow R = (4 x 0.885 + 1 x 0.981)/5 = 0.904
Etc, etc . Until it is as clear as mud! The more races that are
completed the closer we should approximate the skipper's "true" handicap
and the smaller will be the changes to the R value.
DNS, DNF, DSQ etc do not affect the handicap rating, the old value is
just carried forward. Any new skipper to the series will automatically
be awarded the lowest handicap rating of all the competitors in that
race.
(7) Using the ratings in Sailwave Race Scoring Software
First set the scoring properties. Go to SCORING SYTEM, RACE SCORING
click CUSTOM. Enter the following formulae C=E*R, E=C/R and R=C/E. Click
the TEST button to make sure they are functioning.
Enter the boats elapsed times using the SAIL NUM WIZARD. You must input
minutes decimal and then the seconds. Six seconds must be entered as 06.
Then double click on the elapsed time of first boat. Click the RATING
tab. Input your calculated rating for that skipper in the OVERIDE WITH
box. Do so for the rest of the competitors.
Click SCORE (F9) and this should do the trick. If you uncheck the CUSTOM
button and set scoring system to NONE you will get the scratch results.
Remember to rescore after the change. This way you need only one race
file and thus enter data only once to calculate both the scratch and
handicap positions. You can do it for different fleets within the same
race.
Note that when you are calculating a series Race 1 should be excluded
from the handicap series as you won't have a rating for the first race.
Good luck.
Rob Walker
