Serious possible that in the next upgrade of the program you could handicap in system IMS?
Saludos de Miguel Frasquet
miguelfrasquet@ono.com
mfrasquet@jazzfree.com
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Hi Miguel,
Not the next update , but a couple after then. The next update is really a rearrangement exercise, facilitating easier integration of such things as IMS, personal handicaps etc etc.
NB: Do you mean full IMS or default rating IMS or something inbetween - there seems to be N ways in which the IMS data can be used. You can do default rating IMS in Sailwave now using the custom rating system facility (since it only involves one parameter). I’ll also add Americap later which seems to be a simplified IMS-ish-thing.
Regards,
Colin
-----Original Message-----
From: Miguel Frasquet [mailto:miguelfrasquet@ono.com]
Sent: 01 March 2003 11:06
To: sailwave@yahoogroups.com
Subject: [sailwave] Handicaps in IMS
Serious possible that in the next upgrade of the program you could handicap in system IMS?
Saludos de Miguel Frasquet
miguelfrasquet@ono.com
mfrasquet@jazzfree.com
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Colin,
The default IMS rating you are referring to is the General
Performance Handicap (GPH) which is one of the various "Simplified
Scoring Options" that can be used in IMS. They can be found at the
bottom left of the IMS certificate. They are all based on the GPH
and International Level Class (ILC) ratings.
Basically, the ILC rating is for use on normal races and the GPH is
for offshore races.
Just to clarify, here are a couple of excerpts from the Ocean Racing
Club (ORC) minutes:
ORC Annual General Meeting -
"...the Inshore handicap, which is based on ILC with no wind
averaging, should be used for short, inshore races. GPH, which
incorporates the existing wind-averaging spread suitable for long
races, should be used for the scoring of offshore races only, and not
inshore races."
IMS International Technical Committee (ITC) -
"The ITC recommends promoting the use of the ILC average when typical
day races are scored with a single number, although advises that GPH
remains suitable for coastal or offshore races without a predominance
of beating or with unpredictable wind direction."
The simplified scoring options can be used for TOD and TOT so are
extremely easy to use with Sailwave.
The ultimate level of IMS race scoring is to use Performance Curve
Scoring. At this stage, to use this you have to use the ORC's race
scoring package, Altura which is available for the ORC's website:
www.orc.org.
Basically, you can construct a course based on the true wind angles
and the windspeed. The software then uses the predicted time
allowances from the IMS certificate to calculate a Performance Curve
for each boat.
This Performance Curve is your boat's "rating" for this particular
course.
Doing this is a bit of a pain and, in response to this, the ORC put
some constructed courses on the IMS certificate to simplify the
process.
The various types of constructed courses given on the certificate are
as follows:
Wnd/Lwd VMG: Equal legs of optimum beat and optimum run.
Olympic 6-leg: Three legs optimum beat, one leg optimum run, and two
legs reaching 135 degree true wind angle. Each reaching leg is 0.707
times the length of the beat and run legs, which are of equal length.
Circular Rndm: Circular Random, as though a boat circumnavigated a
circular island with wind from a constant direction. Appropriate for
many closed-course races.
Non-Spinnaker: Circular random as above but calculated without the
use of a spinnaker. For use only in races in which the following
restrictions apply to all yachts: a) setting of a spinnaker is
prohibited, b) the entire luff of any jib is attached to the
forestay, c) the clew of the jib may be poled out opposite the boom
only with the yacht's rated spinnaker pole, d) an inner staysail is
permitted and e) a mizzen staysail for which the yacht is rated is
permitted.
Ocean for PCS: A composite course, the content of which varies
progressively with true wind velocity from 30% Windward/Leeward, 70%
Circular Random at 6 knots to 100% Circular Random at 12 knots and
20% Circular Random, 80% reach at 20 knots. It is intended for use
only with Performance Curve or Performance Line Scoring.
So where does that leave Sailwave?
Well, as Colin rightly pointed out, it can be used TOD and TOT with
the GPH and ILC given on the IMS certiciate. (Don't you just hate
acronyms?)
I really can't see Sailwave as being the place where you enter all
the IMS time allowance data.
What might be possible is to get the Performance Curve into
Sailwave. For example, on the Olympic course, there will be a
Performance Curve for each boat. Note that this will depend on the
course leg lengths and conditions on that particular day.
What would be good is if the ORC was a bit more forthcoming about how
it interpolates these Performance Curves from the constructed course
data. Given that information, the actual scoring of a race is
extremely easy.
Colin: I've sent seperately an Excel spreadsheet that explains this
in a bit more detail for a particular race, using the "Ocean for PCS"
constructed course.
Anyway, I hope this clears things up a bit.
Regards
Mike Gill
Ocean Racing Club of Victoria
www.orcv.org.au
...
NB: Do you mean full IMS or default rating IMS or something
inbetween -
there seems to be N ways in which the IMS data can be used. You
can do
default rating IMS in Sailwave now using the custom rating system
facility
(since it only involves one parameter). I'll also add Americap
later which
--- In sailwave@yahoogroups.com, "Colin Jenkins" <colin@s...> wrote:
seems to be a simplified IMS-ish-thing.
...
Thanks Mike, that was an extremely useful and informative message.
If you have the time could you clarify the formula or formulas that
can be used for corrected time using ILC and GPH; I just want to make
sure I've read things right. I'll hardwire them into the rating list
when I can.
Regards,
Colin J
www.sailwave.com
--- In sailwave@yahoogroups.com, "Ocean Racing Club of Victoria
Rudder Cup" <gillmm@n...> wrote:
Colin,
The default IMS rating you are referring to is the General
Performance Handicap (GPH) which is one of the various "Simplified
Scoring Options" that can be used in IMS. They can be found at the
bottom left of the IMS certificate. They are all based on the GPH
and International Level Class (ILC) ratings.Basically, the ILC rating is for use on normal races and the GPH is
for offshore races.Just to clarify, here are a couple of excerpts from the Ocean
Racing
Club (ORC) minutes:
ORC Annual General Meeting -
"...the Inshore handicap, which is based on ILC with no wind
averaging, should be used for short, inshore races. GPH, which
incorporates the existing wind-averaging spread suitable for long
races, should be used for the scoring of offshore races only, and
not
inshore races."
IMS International Technical Committee (ITC) -
"The ITC recommends promoting the use of the ILC average when
typical
day races are scored with a single number, although advises that
GPH
remains suitable for coastal or offshore races without a
predominance
of beating or with unpredictable wind direction."
The simplified scoring options can be used for TOD and TOT so are
extremely easy to use with Sailwave.The ultimate level of IMS race scoring is to use Performance Curve
Scoring. At this stage, to use this you have to use the ORC's race
scoring package, Altura which is available for the ORC's website:
www.orc.org.Basically, you can construct a course based on the true wind angles
and the windspeed. The software then uses the predicted time
allowances from the IMS certificate to calculate a Performance
Curve
for each boat.
This Performance Curve is your boat's "rating" for this particular
course.Doing this is a bit of a pain and, in response to this, the ORC put
some constructed courses on the IMS certificate to simplify the
process.The various types of constructed courses given on the certificate
are
as follows:
Wnd/Lwd VMG: Equal legs of optimum beat and optimum run.
Olympic 6-leg: Three legs optimum beat, one leg optimum run, and
two
legs reaching 135 degree true wind angle. Each reaching leg is
0.707
times the length of the beat and run legs, which are of equal
length.
Circular Rndm: Circular Random, as though a boat circumnavigated a
circular island with wind from a constant direction. Appropriate
for
many closed-course races.
Non-Spinnaker: Circular random as above but calculated without the
use of a spinnaker. For use only in races in which the following
restrictions apply to all yachts: a) setting of a spinnaker is
prohibited, b) the entire luff of any jib is attached to the
forestay, c) the clew of the jib may be poled out opposite the boom
only with the yacht's rated spinnaker pole, d) an inner staysail is
permitted and e) a mizzen staysail for which the yacht is rated is
permitted.Ocean for PCS: A composite course, the content of which varies
progressively with true wind velocity from 30% Windward/Leeward,
70%
Circular Random at 6 knots to 100% Circular Random at 12 knots and
20% Circular Random, 80% reach at 20 knots. It is intended for use
only with Performance Curve or Performance Line Scoring.So where does that leave Sailwave?
Well, as Colin rightly pointed out, it can be used TOD and TOT with
the GPH and ILC given on the IMS certiciate. (Don't you just hate
acronyms?)I really can't see Sailwave as being the place where you enter all
the IMS time allowance data.What might be possible is to get the Performance Curve into
Sailwave. For example, on the Olympic course, there will be a
Performance Curve for each boat. Note that this will depend on the
course leg lengths and conditions on that particular day.What would be good is if the ORC was a bit more forthcoming about
how
it interpolates these Performance Curves from the constructed
course
data. Given that information, the actual scoring of a race is
extremely easy.Colin: I've sent seperately an Excel spreadsheet that explains this
in a bit more detail for a particular race, using the "Ocean for
PCS"
constructed course.
Anyway, I hope this clears things up a bit.
Regards
Mike Gill
Ocean Racing Club of Victoria
www.orcv.org.au--- In sailwave@yahoogroups.com, "Colin Jenkins" <colin@s...> wrote:
>...
> NB: Do you mean full IMS or default rating IMS or something
inbetween -
> there seems to be N ways in which the IMS data can be used. You
can do
> default rating IMS in Sailwave now using the custom rating system
facility
> (since it only involves one parameter). I'll also add Americap
later which
> seems to be a simplified IMS-ish-thing.
> ...
Colin,
No problem. The first thing you will need is an example IMS
certificate. You can find one on the ORC website at
http://www.orc.org/parvir02.pdf. Please note that this is a 2002
certificate. The 2003 certificate is slightly different.
The bit you will need is at the bottom left, entitled "Simplified
Scoring Options".
For the standard ToT and ToD, use the numbers as suggested. You know
more about them than I do. I have no idea why the Inshore ToT uses
675 instead of 600. The ORC are not very forthcoming about this
stuff.
The acronym TMF means Time Multiplication Factor which I'm guessing
you already know. Usually, the potentialy fastest boat is used as
the scratch boat for calculating the corrected time. Hence, you end
up with the formula (for an Inshore course):
IMS TMF = (675/ILC for the fastest boat) / (675/ILC for subject boat)
Then Corrected = Elapsed * IMS TMF
A relatively recent development is the Performance Line Scoring.
This method approximates the Performance Curve I mentioned in my last
email. Hence, the curve of sec/mile (also known as TA - time
allowance) vs wind speed is replaced by a straight line approximation.
The formula is at the bottom of the cetificate:
Performance Line Corrected Time = (PLT * Elapsed Time) - (PLD *
Distance)
where PLT (Performance Line Time) and PLD (Performance Line Distance)
are taken from the certificate (two right hand columns of the
Simplified Scoring Section). They give two different numbers for
Ocean and Olympic courses. Most people use the Olympic course, as
Ocean courses are better scored using the Performance Curve method.
Colin, I think that the Performance Line Scoring method would be the
method for you to concentrate on. By including three IMS scoring
methods (ToD, ToT and PLS) you should get a fair number of clubs to
use Sailwave.
It would also be a good lobbying point with the ORC to release some
of their calculations for Performance Curve scoring.
I came across a good quote from Rob Humphreys on the IMS
rule: "...unlike the IOR, the IMS is not really a rule at all, it is
a system composed of three discrete parts one the measurement
process, two the performance-prediction number-cruncher, and three
the almost mystical handicap veil."
The "secret" calculations that are at the heart of the IMS rule
center around the VPP (Velocity Prediction Program),
Rod's "performance-prediction number-cruncher". This program
takes the boat measurements (right side of IMS certificate as well as
the hull offset file) and then calculates the Time Allowances you see
on the middle left of the IMS certificate. They keep it secret so
that designers find it hard to optimise their designs for IMS. This
was in direct response to some of the more dangerously unstable
designs that came out of the old IOR rule.
However, I see no reason why they can't release the method for
converting their Performance Curves to a formula for use in scoring
applications. Rod rightly referrred to this as IMS' "mystical
handicap veil" which is counter-productive to the take-up of IMS in
my opinion.
Sorry - bit of personal bugbear, this one.
Anyway, hope this clears up the IMS Simplified Scoring Options.
Regards
Mike Gill
www.orcv.org.au
Thanks Mike, that was an extremely useful and informative message.
If you have the time could you clarify the formula or formulas that
can be used for corrected time using ILC and GPH; I just want to
make
sure I've read things right. I'll hardwire them into the rating
list
--- In sailwave@yahoogroups.com, "Sailwave" <colin@s...> wrote:
when I can.
Regards,
Colin J
www.sailwave.com
Sorry,
The a full stop got attached to the URL. Use...
http://www.orc.org/parvir02.pdf
Regards
Mike Gill
www.orcv.org.au