A bit of history that your club CRAM and mine CRAC experienced back in the day. Our clubs used the NAMSA catamaran rating system administered by Herb Malm. US Sailing took over the Dixie portsmouth system and with Darline Hobock taking the volunteer lead made a commitment to support the multihull racing scene. Both clubs vigorously debated a move from NAMSA to US Sailing Portsmouth. I have a vague memory of speaking with Roger Cochran at the time. The core principals remain the same and are:

Accuracy How close are the ratings to the true rating of the class.
Transparency Do the rank and file racers KNOW what data and methods are used to generate changes in the ratings and do they think this process is fair.
Authority The yacht clubs and catamaran clubs want to know that they have the support and approval of regional and national bodies that can settle all disputes.
Robustness. Can the ratings quickly get to a fair rating for all of the boats that want to go racing. Recalculating last seasons results using the New... better more accurate ratings (not saying I did this....errrr ahem...) is just nuts.

Concurrently, the kind donation of the Hoyt Jolley endowment to support a multihull championship within US Sailing Adult Championship programs was a powerful incentive for most clubs to switch from NAMSA to US Sailing Portsmouth. The idea was that sailors would use one handicap system to go racing. The Authority of US Sailing was a big factor in CRAC's decision to change to USPN.

The Robustness of the Dixie portsmouth system was limited because it is founded on the premise that fleets of one design class boats are being rated. Catsailors of course are constantly trying out modifications to their one design class. This presents a unique challenge to rating systems that presume a fleet of boats. One offs, or changes in rigs, sail areas, boards, etc etc etc are, by definition, not a fleet of boats. The solution of course was to modify the Dixie portsmouth system that was founded on statistical data collection of class data by creating a table of flat percentage modifications. Presto... the statistical system was now robust!

In 2018, the criteria are the same.. Accuracy, Transparency, Authority and Robustness.

Analysis of the SCHRS 2017 measurement rating table was compared to race results from the French racing scene for these classes.

Summary chart for C1 AHPC Viper Double Nacra 20 carbone F18 A Class classic Nacra 17 old Olympic

The SCHRS annual review states. (I can get permission to forward you a copy if you need)

2.4 All these differences are below 2% and most are as expected. There is nothing here to compel us to make any changes to the formula.
Summary SCHRS is accurate

SCHRS is transparent. Its a measurement rule and ALL of the class OD measurements are published as is the formula used to calculate the ratings. The web site has the data and calculators. Measurement is provided by World Sailing certified individuals.

SCHRS has the authority of World Sailing and US Sailing will be including SCHRS information in the handicap systems that US Sailing supports. (All handicap sailing administration has been moved under the off shore committee.)

SCHRS is Robust. A modification to a one design class is measured and the rating for the specific boat is calculated. A one off design can be measured and a final rating for that boat determined. For the owner.... his rating is by definition "accurate" and independently determined and reproducible since approved measure's use the same techniques. For the fleet, The modified boat is rated using the same methods used for their rating.

Final point, the UK RYA portsmouth system is a statistical system as well but fundamentally different in design then the US system. The UK system rates 10 catamaran classes because those are the active UK fleets that can generate yearly returns. They use a hybrid system for anyone with a boat in the dead boat society.

Will Rottering (Houston Area) is the US representative replacing me going forward. I and another volunteer serve on his US committee.

We would be delighted to answer any questions you have and World Sailing has been extremely responsive in getting final answers to any concerns we have raised.

Last edited by Mark Schneider; 01/26/18 03:49 AM.