I've been pressured into re-introducing skipper handicaps into some of our club racing series.
I think NHC will make this task easier. Is the algorithm for adjusting ratings in the public domain? reference ?
If I re-score a previous series with NHC, I see that the top boats get a higher number than their base (PN) and the bottom boats a smaller no. I would have expected it to be the other way, but can't confirm without insight how the system works.
···
--
regards,
Malcolm Osborne
Sedgefield South Africa
I'm attaching two documents that I have from when I looked at this at
the beginning of the year.
One is a step-by-step walk-through of the calculations. This is my idea
of the calculations. So far as I can remember, it is accurate but it is
possible I had minor corrections that I never inputted.
The second is an Excel spreadsheet that shows the calculations for an
actual race. I assume I got this from Jon as the properties show him as
the author. You can go through the formulas in the cells.
I never followed up on this as some of the assumptions that the NHC
system makes didn't really make sense to me. I must admit I don't
remember my exact problems now.
Locally, we do skipper handicaps as follows:
a. Determine the corrected time of the median boat (middle boat or
average of the two middle boats)
b. Calculate the rating that each boat would need to tie with the median
boat
c. Calculate the difference between the current rating and the
"calculated" rating from step b
d. Adjust the rating for each boat by some percentage of the difference
calculated in step c, we use 15% (you might want to include a maximum
amount that a boat can change each race - we do)
Sailwave can do the first two steps IF you use the 1st-place boat
instead of the median boat. Unfortunately, that introduces a systematic
bias such that all boats that sail gradually get a faster and faster
rating so that a new boat could have a significant advantage when it
starts sailing. Using the median boat eliminates, or minimizes, that bias.
Art
···
On 8/27/2013 3:09 PM, Malcolm Osborne wrote:
I've been pressured into re-introducing skipper handicaps into some of
our club racing series.
I think NHC will make this task easier. Is the algorithm for adjusting
ratings in the public domain? reference ?
If I re-score a previous series with NHC, I see that the top boats get a
higher number than their base (PN) and the bottom boats a smaller no. I
would have expected it to be the other way, but can't confirm without
insight how the system works.
Hi Malcom,
You can find details of the NHC system here http://www.rya.org.uk/racing/Pages/NHC.aspx
On the right of the page there are links to downloads which explain the calculations.
Have a browse of these and if you have any questions I’ll be pleased to try and answer them.
NHC consists of 2 different models 1 for Club racing and 1 for Regattas.
Sailwave supports both. It supports them either through internal calculations where all the calculations are fixed and is simple to use, or through external mode where it uses an Excel spreadsheet. This gives proof of Calculation and enables flexibility.
In the spreadsheet mode there is a template which contains all the rules of the calculation. If you want to develop your own rules then you can modify this template and develop any rules you want.
Put simply when you click score within Sailwave, Sailwave scores the first race and then makes a copy of the template and fills it in with the details. The new handicap for race 2 is calculated within the spreadsheet. Sailwave picks this up and sets this as the rating for race 2. It then scores race 2 and passes the results to the template again. This repeats for all races. If you try it out, its quite intuitive. So basically you can make it do anything you like with the ratings.
NHC is specified around Time correction factor and the speadsheet is written around TCF. If you look at the template there are 2 or 3 worksheets - one of these is a config sheet. Sailwave can also do a conversion of PY to TCF and back to PY if you want to experiment with files that are configured for PY
Let me know if you have any questions
Jon
···
Jon Eskdale
Sailwave
03333 443377
07976 709777
On 27 August 2013 23:09, Malcolm Osborne malcolmo@telkomsa.net wrote:
I’ve been pressured into re-introducing skipper handicaps into some of
our club racing series.
I think NHC will make this task easier. Is the algorithm for adjusting
ratings in the public domain? reference ?
If I re-score a previous series with NHC, I see that the top boats get a
higher number than their base (PN) and the bottom boats a smaller no. I
would have expected it to be the other way, but can’t confirm without
insight how the system works.
–
regards,
Malcolm Osborne
Sedgefield South Africa
Jon and Art,
Thank you for the information. I'll see how I go with SW's NHC.
Could the spreadsheet template be modified to accommodate corrections based on median performance, as Art does it?
regards,
Malcolm Osborne
Sedgefield South Africa
···
On 2013/08/28 09:27, Jon Eskdale wrote:
Hi Malcom,
You can find details of the NHC system here http://www.rya.org.uk/racing/Pages/NHC.aspx
On the right of the page there are links to downloads which explain the calculations.
Have a browse of these and if you have any questions I'll be pleased to try and answer them.
NHC consists of 2 different models 1 for Club racing and 1 for Regattas.
Sailwave supports both. It supports them either through internal calculations where all the calculations are fixed and is simple to use, or through external mode where it uses an Excel spreadsheet. This gives proof of Calculation and enables flexibility.
In the spreadsheet mode there is a template which contains all the rules of the calculation. If you want to develop your own rules then you can modify this template and develop any rules you want.
Put simply when you click score within Sailwave, Sailwave scores the first race and then makes a copy of the template and fills it in with the details. The new handicap for race 2 is calculated within the spreadsheet. Sailwave picks this up and sets this as the rating for race 2. It then scores race 2 and passes the results to the template again. This repeats for all races. If you try it out, its quite intuitive. So basically you can make it do anything you like with the ratings.
NHC is specified around Time correction factor and the speadsheet is written around TCF. If you look at the template there are 2 or 3 worksheets - one of these is a config sheet. Sailwave can also do a conversion of PY to TCF and back to PY if you want to experiment with files that are configured for PY
Let me know if you have any questions
Jon
Jon Eskdale
Sailwave
03333 443377
07976 709777
Hi Malcolm,
The spreadsheet - does use median - You can do anything (well almost anything!!) with the spreadsheet
Jon
···
Jon Eskdale
Sailwave
03333 443377
07976 709777
On 28 August 2013 11:29, Malcolm Osborne malcolmo@telkomsa.net wrote:
Jon and Art,
Thank you for the information. I'll see how I go with SW's NHC.
Could the spreadsheet template be modified to accommodate
corrections based on median performance, as Art does it?
regards,
Malcolm Osborne
Sedgefield South Africa
On 2013/08/28 09:27, Jon Eskdale wrote:
Hi Malcom,
You can find details of the NHC system here http://www.rya.org.uk/racing/Pages/NHC.aspx
On the right of the page there are links to downloads
which explain the calculations.
Have a browse of these and if you have any questions
I’ll be pleased to try and answer them.
NHC consists of 2 different models 1 for Club racing
and 1 for Regattas.
Sailwave supports both. It supports them either
through internal calculations where all the calculations
are fixed and is simple to use, or through external mode
where it uses an Excel spreadsheet. This gives proof of
Calculation and enables flexibility.
In the spreadsheet mode there is a template which
contains all the rules of the calculation. If you want
to develop your own rules then you can modify this
template and develop any rules you want.
Put simply when you click score within Sailwave,
Sailwave scores the first race and then makes a copy of
the template and fills it in with the details. The new
handicap for race 2 is calculated within the
spreadsheet. Sailwave picks this up and sets this as
the rating for race 2. It then scores race 2 and passes
the results to the template again. This repeats for all
races. If you try it out, its quite intuitive. So
basically you can make it do anything you like with the
ratings.
NHC is specified around Time correction factor and
the speadsheet is written around TCF. If you look at
the template there are 2 or 3 worksheets - one of these
is a config sheet. Sailwave can also do a conversion of
PY to TCF and back to PY if you want to experiment with
files that are configured for PY
Let me know if you have any questions
Jon
Jon Eskdale
Sailwave
03333 443377
07976 709777