BAMA Ratings Discussion
Objective of the Discussion
• Discuss the various rating methodologies and
gain a mutual understanding of their pros and
• Determine if we want to have one ratings
methodology or multiple ratings methodologies
(depending on the class of boat)
• Write-up final decision and apply ratings based
on the written guidance to provide consistent
– “Consistent” does not equal “Fair”
Fundamental Issues
• How a rating is determined is different from the
overall process regarding applying for a rating,
appealing a rating, and challenging a rating.
• Ratings can be applied in a Time on Time manner
or a Time on Distance manner
• There are two fundamental ways of determining
– Predictive
– Observational
Overall Rating Process
• The YRA has a well defined process describing
how one applies for a rating, the appeal
process, and challenging a rating.
• BAMA’s process currently mirrors the YRA
• However, how is the rating determined in the
first place? And how is it updated?
Ratings Rules can be Grouped into 2
Main Categories
• Predictive Rule:
– You take a lot of measurements of the boat and then
use a complex algorithm to predict the boat’s speed
– Examples of this type of rule are Texel and IRC
• Performance Rule:
– You use a boat as the base boat and then rate the
other boats as plus or minus to that base boat based
on observed performance
– Examples of this type of rule are PHRF and
Time on Time vs. Time on Distance
TOD is how PHRF is calculated
– It assumes that it takes a boat a fixed number of seconds to cover a mile – regardless of wind
– Therefore, if a boat that rates 0 takes is assumed to take 560 seconds, a boat that rates 40 is
assumed to take 600 seconds to cover the same mile
– The problem is that with high performance boats, unlike displacement monohulls, the rate at
which they cover a mile greatly varies
– The problem is that very fast boats can not continue to accelerate indefinitely as the wind
speed increases, but they remain very fast in light winds
In light winds the high performance boats will almost always win
In high winds the slow boats will almost always win
This is what BAMA has historically observed – dominance of the maxi beach cats in light wind races
such as the Great Pumpkin vs. the results of boats like Aotea in heavy wind DHFs where they placed at
the back of the pack as they would have needed to average over 30 knots to win on corrected time
TOT is how Texel and Portsmouth are calculated
– It is assumed that the ratio of boatspeed between boats is constant
So, if a fast boat is 50% faster than a slow boat in light winds, it should be about 50% faster than a
slow boat in high winds
This ratio holds up much better than TOD
Ratings Methods
• Predictive:
– Texel
• Observed Performance:
– Portsmouth
– Golf
Predictive Rule:
– Depends on many measurements of the boat to then utilizes a formula to determine
predicted speed
– Utilizes Time on Time to score races
– It is the way that most multihulls around the world are raced, so easier to compare our ratings
to boats around the world
– Percentage differences of speed between boats are somewhat constant over relatively large
variations of boat and wind speed, and thus can produce a more accurate first-order
approximation for race scoring
– Non-political: formula generates the rating
– Can be converted in PHRF using a conversion method
– Not rated the same way as the monohulls in the Bay Area so need to ensure that Multihulls
are not racing against monohulls directly (SSS, beercan races)
– Utilizes Time on Time so PHRF race committees might have difficulty/resistance to
– Great difficulty in slotting into pursuit races (i.e. Three Bridge Fiasco, Great Pumpkin)
– No flexibility if observed performance greatly differs from predicted performance
• Observed performance system that provides a single handicap number
that adds or subtracts a fixed number of seconds per mile from a “0” boat.
– The boat is assumed to be raced to its full potential
• Pluses:
– YRA uses this system so we are in line with the monohulls
– All race committees on the bay know how to calculate results using the system
• Minuses:
– Multihulls have a wide performance envelope that a single number handicap
does not effectively capture
– Determining how fast the boat will be when sailed “optimally” can be difficult
– Can be discouraging for new sailors as they have limited opportunity to
– Difficult to determine ratings for “one-off boats” or boats with limited
observed perfomance
• Observed performance system – performance
relative to a “base” boat
• 3 different numbers depending on wind strength
• Issues
– Which number do you choose if you move from one
section of the bay to another?
– What do you do about boats not on the Portsmouth
list? What do you use as your first rating?
– Time on Time calculation is not utilized by most race
committees in the bay
• The race results are analyzed and the size of each boat’s handicap is
computed to allow everyone an even chance of winning based on the
actual race performance of their boat
– So, a fast F-27 might have a rating of 38 and someone who has just joined the
fleet with an F-27 and has not had success might have a rating of 150
• Pluses
– All boats have a chance of wining
– Decreases arguments regarding what is the “right” rating for a boat as it is just
a calculation dependent on actual results
• Minuses
– Competitive racers can become frustrated if people who are not racing well
win a lot
– Not rated the same way as the monohulls in the Bay Area so need to ensure
that Multihulls are not racing against monohulls directly (SSS, beercan races)
– Great difficulty in slotting into pursuit races (i.e. Three Bridge Fiasco, Great
Dash 750 – Example of Challenges
• National Rating – PHRF 36
• Texel Rating without spinnaker (Gary Helms’ application) –
– What do you use for measurements for Texel rating rule?
• Need to measure sails and weigh boat, takes time and money
• Bigger floats than Sprint 750, so should be faster in heavier
air theoretically – PHRF 30-33
• BAMA currently rates to “Central Bay Conditions”, i.e. heavy
– F-24’s are rated significantly lower than the national number (69
vs. 84) and are quite competitive
– Should the Dash 750 also be rated below the national number?
• Observed performance to date says “no”
• But it is a close relative of the F-24 so why not?
Rainbow – Example of Challenges
Old “Smoky Room” PHRF was 90
First Texel based rating was 180
Auto-calculation Texel Rule PHRF is 320
“Raced-to” PHRF is in the low to mid 400s
Current rating is 261
Texel challenges
– Not easy to weigh boat
– Sails are from design specs only
Ratings Options for BAMA
• Two big issues:
– How do you generate the initial rating?
– How do you deal with re-rating boats?
– The answers to both issues don’t need to be the
• For example, you could use one rating rule for the
initial rating and then another for the re-rating and
convert both to PHRF numbers
General Issues
• Do we want to be able to race directly vs. monohulls
like in SSS?
• Do we want a non-spinnaker credit? If so, how big?
• Do we want “one-design” ratings or each boat rated on
its own?
– Example: large weight differences amongst the F-27s and
• Can you change your sail inventory and hence your
rating mid-season?
• Should the committee re-rate mid-season?
• Other?
Proposed Process
Proposed Ratings Process
• BAMA will continue to rate boats under PHRF to enable
widest possible participation of our members in Bay Area
• Initial Rating for all boats will be based on Texel but
converted in PHRF numbers
– Utilizes established prediction rule to generate initial number
– Committee will utilize:
• Direct measurements if member wants to provide them
• If member is not interested in providing direct measurements then
committee will utilize either:
– Most disadvantageous measurements from a sister-ship that has had direct
– Design specs if no measured sister-ship
– Rating will be provisional
Proposed Ratings Process
• Provisional Ratings can be:
– Changed by the committee
– Appealed by the racer
– Challenged by competitors
• The committee will review actual race data including:
– Finish data
– Skipper interviews
– GPS tracks
• The committee will generate “sailed – to” ratings for races the boat has
raced in and evaluate whether the boat is actually performing as the Texel
prediction program indicated it should be
• If the committee determines that a ratings change is warranted it will
provide a written explanation of its rational
– The ratings changes will be dependent upon the committee members best
judgments, but they will be based upon actual results for the boat in question
– Committee’s goal will be to base rating upon boat performance capability, not
skipper capability
• Interviews with racers (including the skipper of the boat) about how well the boat is racing
• GPS tracks

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