I went through the outline and ran a test with 2 boats to save time . the phrfs are over 90 points apart. I entered the exact race time for both boats and they ended up tied.
On 05/07/2015 21:45,
[sailwave] wrote:
I am looking to setup sailwave for a 10 boat fleet.We race using PHRF time on time. Any suggestions?
Thanks Craig
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What A and B factors were you using to calculate the TCF?
Mark Townsend
Phone: 562-433-4366
Cell: 562-533-5909
Email: s_mark_townsend@hotmail.com
From: sailwave@yahoogroups.com [mailto:sailwave@yahoogroups.com]
Sent: Sunday, July 05, 2015 6:15 PM
To: Huw Pearce huw.pearce@bcs.org.uk [sailwave]
Subject: Re: [sailwave] new to sailwave
I went through the outline and ran a test with 2 boats to save time . the phrfs are over 90 points apart. I entered the exact race time for both boats and they ended up tied.
On Jul 5, 2015 5:03 PM, “Huw Pearce huw.pearce@bcs.org.uk [sailwave]” sailwave@yahoogroups.com wrote:
Hi Craig,
Welcome to Sailwave. A good get you started guide has been written Mark Townsend and is available at http://www.abyc.org/upload/Sailwave_ABYC_User_Guide.pdf.
The document should help you set-up what you need.
Kind regards,
Huw
On 05/07/2015 21:45, craig_windsurf@yahoo.com [sailwave] wrote:
I am looking to setup sailwave for a 10 boat fleet. We race using PHRF time on time. Any suggestions?
Thanks Craig
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There are two ways to implement PHRF TOT scoring: (1) convert the PHRF
values to TCFs and then score with the TCFs or (2) use the built-in
functions in Sailwave to convert and score. I would recommend the first
method although either should be acceptable. By the way, the scoring
formula for TOT is: CT = ET * TCF (CT=corrected time; ET=elapsed time;
TCF=time correction factor).
The first method allows competitors to follow the calculations fairly
easily while the second is slightly less work to set up. My club has
switched to using the first method because it is easier for the
competitors to follow and understand - we post a sheet showing the
standard PHRF ratings (expressed in sec/mi and intended for TOD scoring)
and the corresponding TCFs to be used for TOT scoring (rounded to 3
decimal places). We then use the TCF scoring in Sailwave. We create the
values to post in the conversion sheet using Excel (the formula is
simple - TCF = A/[B+PHRF]). This makes it easy for competitors to check
the corrected times themselves and also makes it fairly easy for the RC
to troubleshoot (though that shouldn't be much of an issue).
Sailwave has a built-in ability to do the conversion but it doesn't
display the TCF used to score but instead displays the PHRF standard
ratings (which are sec/mi and intended for TOD scoring). That means that
competitors cannot simply multiple the ETs in the results by the TCFs in
the results to confirm that the CTs are in fact calculated correctly.
We tend to think the first method (using TCF scoring in Sailwave) helps
the competitors to have confidence in the competence of the RC. In fact,
we have seen events where the races were claimed to have been scored as
TOT when in fact they were scored as TOD but no one ever realized the
mistake, possibly because the published results showed TOD ratings
rather than TOT TCFs (in one such event, 1st should have been 4th and
vise versa - a fairly significant mistake).
The A and B factors in the conversion formula (TCF = A/[B+PHRF]) have
different functions. The B factor represents the windspeed (in sec/mi of
boatspeed for a 0-rated boat) at which you think your TOD ratings are
accurate. If your local TOD ratings are optimized for 10-12 kts of wind
around a standard windward/leeward course then the B conversion factor
should be in the range of 600-650. The B factor represents the windspeed
at which your TOT and TOD results will be the same so you want to aim
for a factor that represents the average for your locale.
The A factor has no impact on the order of boats and only determines
which boat will be the 0-rated boat under TOT. The recommendation is to
make the A factor equal to the B factor so that a boat that rates 0 with
the standard TOD ratings (so CT = ET) will have a TCF of 1.000 (so CT =
ET will also be true).
Art
On 7/5/2015 6:14 PM, Craig craig_windsurf@yahoo.com [sailwave] wrote:
I went through the outline and ran a test with 2 boats to save time . the phrfs
are over 90 points apart. I entered the exact race time for both boats and they
ended up tied.On Jul 5, 2015 5:03 PM, "Huw Pearce huw.pearce@bcs.org.uk [sailwave]" > <sailwave@yahoogroups.com> wrote:
Hi Craig,
Welcome to Sailwave. A good get you started guide has been written Mark
Townsend and is available at
http://www.abyc.org/upload/Sailwave_ABYC_User_Guide.pdf.
<http://www.abyc.org/upload/Sailwave_ABYC_User_Guide.pdf>The document should help you set-up what you need.
Kind regards,
HuwOn 05/07/2015 21:45, craig_windsurf@yahoo.com [sailwave] wrote:
I am looking to setup sailwave for a 10 boat fleet. We race using PHRF
time on time. Any suggestions?Thanks Craig
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