In 2017 we simplified the core formula to:
1.111 x W0.3
L0.325 x A0.41
where W is all up sailing weight, L is length and A is sail area. This has had little effect on the ratings but makes the formula easier to manage, the details are explained further in the paper here.
The 2016 review includes a major overhaul of the data. Wherever possible it is now in line with class rules. It also includes some minor changes to the formula which are explained in the paper here.
Inclusion of a Downloads page, replacing the original "Calculator" link and page. This now inlcudes the latest Calculator, Individual rating request form and the latest World Council review paper.
The SCHRS ratings have been reviewed for 2015. A full description of the changes are given in the attached paper, see the paper here... further information is available from William Sunnucks.
The appointment of Jean-Claude Rouves as Chairman of SCHRS has been approved.
Nick Dewhirst Chairman of the World Council of SCHRS sadly died in July 2013. This was a great loss to the world of catamarans where his experience and his persuasive quality were appreciated by all.
Following extensive discussions the Committee has appoint M. Jean-Claude Rouves as its new Chairman. According to the constitution we have applied for ratification from the World Sailing Equipment Committee, something that we expect to receive shortly.
The SCHRS ratings have been reviewed for 2014. A full description of the changes are given in the attached paper, see the paper here... further information is available from William Sunnucks. Included are some provisional ratings for some foiling boats. So far data on the performance of these boats is scarce, and it may be necessary to review the figures during the season.
Amended ratings for Nacra 16 and Nacra 17 following receipt of measurement data for production boats. Previous ratings were based on measurements on the prototypes.
Correction to Sprint 15 DX, re-instatement of the application of the Rated Length adjustment.
Additional data for Formula 16 classes added at the request of the International Formula 16 Association.
2013 Formula updates
Minor changes to the formula approved by the World Council for the 2013 sailing season including:
- adjustment to the crew weight assumption to recognise that smaller catamarans can be sailed by lighter people
- softening of the board correction penalty for long boards
- introduction of a formula for gennakers - headsails that can't be used upwind, but breach the 75% SMG/SF limit
- minor adjustment to the power factor calculation
- Jib area diagram changed to conform with the method used by Texel
A full description of the changes are given in the attached paper, see the paper here... further information is available from William Sunnucks.
Hurricane 5.9 update
Review of Hurricane variants in the UK, incorporating up to date weights and the square top mains on the Hurricane SX.
2012 Formula updates
Formula changed to address anomalies raised by the FFV, the Texel rating team and the F16 class. A full description of the issues and changes are given in the attached paper. Click here to see the paper...
Introduction of revised Board Correction Formula
A new board correction (BC) formulation has been created to fix an anomaly in the previous formula, which has only become a problem now that very high aspect ratio boards are being used on some boats. The previous BC correction started reducing again for a board aspect ratio greater than 5, due to its quadratic nature. The new formulation is asymptotic such that it continues to increase and tend toward a final value for very high aspect ratio boards. The new formulation has very little effect except for boards with aspect ratios of 5 or more. The proposed formula is BC=15-15/(XB^0.1045)+2. XB is the aspect ratio of the board, there is no penalty for larger boards, just for the aspect ratio, which reflects efficiency.
A new method for measuring the length of the board (VLB) has been created this will give a very small penalty for curved boards, where depth will be measured around the circumference. It will also give a small penalty for T foils, as the length of the horizontal section will be included in VLB. This is an interim measure. A full review will be needed when and if curved boards and T foils start to show a significant and consistent advantage.