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Understanding the -Ewin Column
There has been some confusion expressed over the -Ewin column in the new scoring tabulation. After doing some looking and number crunching, I think I know the source of the confusion...
The -Ewin column is NOT corrected seconds behind. It represents the amount
of time each individual boat would have to shave off their elapsed time in
order to tie the winning boat. The confusion is pretty understandable when
one considers that we are accustomed to seeing 'Seconds Behind' in the Thorgeson
software.
The -Ewin column takes into account that we are racing Time on Time, that
each boat has a different rating, and that the finish for each boat
actually depends on the elapsed time of every boat in the class.
If one thinks about it, the -Ewin column is actually a better piece of
information. It states how much better each boat would have had to perform
(in real time, not corrected), in order to win, or tie to win. The 'Seconds
Behind' we are all accustomed to is a bit misleading since it is in CORRECTED
TIME SECONDS, a number that is the difference between not one, but TWO,
corrected time computations!
Try it:
CT = 600 ET / (Rating + 480) is the formula we use...
In Series 1, Race 4:
PHRF Spinnaker Fleet - Start time: 18:33:00
|
Pos
|
Class |
Boat |
Sail# |
Skipper |
Rate |
Elapsed |
-Ewin |
Corrected |
Rwin |
Pts |
|
1st
|
PHRF Spinnaker |
Martin 242 |
911 |
Bill Rose |
153 |
00:56:24 |
00:00:00 |
00:53:28 |
152.918 |
1 |
|
2nd |
PHRF Spinnaker |
J27RF |
23 |
Burns Brown |
132 |
00:54:35 |
00:00:03 |
00:53:31 |
132.531 |
2 |
|
3rd |
PHRF Spinnaker |
J22 |
498 |
Jeff Kitterman |
177 |
01:00:11 |
00:01:38 |
00:54:58 |
195.374 |
3 |
Note that Jeff's Corrected Time Behind is 54:58 - 53:28 = 1:30.
But his -Ewin is listed at 1:38 ...
How could this be?
Well, if Jeff had sailed 1:38 faster around the course, then he would have
tied Bill for first place.
Subtract 1:38 from Jeff's elapsed time:
01:00:11 - 1:38 = 00:58:33
which is 3513 seconds.
Using the Time on Time formula...
CT = 600 ET / (Rating + 480):
CT = 600 (3513) / (480 + 177)
CT = 600 (3513) / (657)
CT = 3208.2192 (seconds)
to convert to minutes:
CT = 3208.2192 / 60 = 53.466667
so we have 53 minutes, but to convert the fractional part into seconds:
..466667 * 60 = 28 seconds
which would have given Jeff a corrected time of 53:28... exactly what Bill's
1st place corrected time was.
That's what -Ewin is all about. Finding out how much better everyone else would have had to sail to tie the winner!
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