Scooby,

You are not entirely correct in your argument. While you make proper points in relation to the A-cats, you are wrong to carry these points over to the Formula classes. Indeed the A-cats can differ significantly in their setup but formula boats can not. That is with one exception and that is daggerboards, but this daggerboard rule in SCHRS has long been regarded as a problem point for SCHRS, not because of the new designs but as a direct result of the Hobie 17. I will explain.

SCHR rates a boat in the following inputs :

-1- Number of crew
-2- miniumum boat weight
-3- Overall length
-4- Water line length
-5- Max mainsail area
-6- Vertical luff of mainsail
-7- Max jib area
-8- vertical luff of jib sail
-9- Spi area
-10- Board area
-11- board depth

None of these input change from boat to boat when looking at formula boats,expect the last two. In the way of A-cats however it can be different.

Most of these points are ruled upon directly by formula class rules; the other points which are not are effectively limited by the other rules. Example F16 directly limits mainsail luff length while F18 does not but all F18 mainsail lufflengths end up between 8.5 mtr and 8.6 mtr. any because of the limit on mast height and the fact that a low boom is a serious disadvantage in racing. This difference of 0.1 mtr. does not change the rating in any significant way, that is unless the basic rating is right on the rounding off boundery and this change may just push it over. With respect to differences in waterline length and overall length. The measurements based rating systems often equate the two to the maximum value possible to either one, so their is no way any real life boat can get an advantage on that aspect no matter how weird the bows are.

So what I'm saying here is that no F18 modern or old will end up at a rating faster then listed, they can only arrive at slower ratings. Under Texel this is the case. Under SCHRS there is one exception. The daggerboards calculations (not present in such a form in Texel)

SCHRS has a rather crude formula behind their daggerboard calculations. In effect it only looks at the aspect ratio of the boards and not the real area, even while the last is indeed an input value ! In effect a Hobie 17 with miniscule boards gets a large hit because of it, one that is not realistic. I think SCHRS even tweaked the H17 rating to correct this somewhat. The F18's however are still rated with 0.23 sq.mtr x 1 mtr daggerboard.

This is nonsense on todays F18's and I think it was nonsense even when the rating was calculated for the first time. Example :

Go to the SCHRS site and download the rating calculation sheet. Now change the board dimensions form 0.23x1 to 0.0144x0.25 (both sets have the same aspect ratio) ; The last set of numbers is the size of a windsurfer fin. The rating for the F18 doesn't change AT ALL, not even in the 6th decimal.

Of course the 0.23x1 board has alot better windward performance then the 0.0144x0.25 fin ! This is where SCHRS can go wrong. But I must say that the danger is pretty small as not many designers will fit their F18 boats with fins over properly designed daggerboards, you won't sell much F18's that way.

So in all honesty there is no way that a Capricorn F18 can end up at schrs 0.98 ! It may just end up at 1.00 over 1.01 because the basic F18 rating is indeed very close to the rounding off threshold, as it is 1.006197. So any change has only the change the basic rating by 0.0012 (= 0.1 %) to have it round off downward instead of upwards.

Even if I maximize the SCHRS rating for the F18 (basic rating = 1.006197) by maximize all parameters that I can think of :

8.65 mtr. luff over 8.5 mtr.
5.5 mtr jib luff over 5.2 mtr.
Keeping board dimensions as changing those will only make the rating slower.

I then only arrive at 1.002647 = ONLY 0.0035 slower then the basic rating = 0.37 % slower. This is very negligiable.

The cases for the F16 and F20 are very much the same. So I direct the 0.98 capricorn to the world of unfounded rumours, because if it truly had that number then it would definately NOT measure in as an F18.

Like I said A-cats can be different because they have no limits on mastheight etc.

Wouter