With reference to Claus response, it seem that there is a big imbalance between what is happening on the water ( PY ratings) and what can be predicted using simple formula. I think this is why a lot of clubs/ sailors are reluctant to jump into measurement rules if they know they will be at a disadvantage before the gun goes. This may come from a number of areas: One design sails, old hull design, basic deck gear, too light, too narrow etc. How do you address this problem in a formula rule? Don't get me wrong I believe in the formula route but obliviously it needs constant adjustment to even the playing field and still holding on to the single number rating. This is a tough nut to crack.

Maybe the best solution is to have both systems in one, so you have the information from Colin sailwave program and it pumps out an PY adjustment (fudge value) number that's added to the SCHRS or Texel rules and you should have a more precise rating system, the best of both wolds. Each system keeping the other in check. what should happen is with all the returns to the sailwave system the fudge factor will get tighter and tighter. Okay Wouter and Simon I'm ready to get flamed.

On a different tack which is giving better results on the water between Texel and SCHRS, with both being formula rules they should be coming out close, from Claus attachment you get big difference the further you go away from the F18 base line ratios, the Hobie 16 is old and a OD and the A-Class too light. What you are seeing is type forming, it happens in every formula rule, it's the nature of the beast.