Bill and all,
Ok,.here are some number.
Took them off the Performance site

TOTAL Sail Area ( s.f.)

I17normal ( not R) 160
I18 227
I20 247

As a percentage increase sail area, using the I17 as a basis

I 17 100%
I 18 141% ( main and jib)
I 20 153% ( main and jib)

Correct me if I am wrong, but wasn't the I-18 the first in this family of design?
And all the I series use the same rudders and d-boards.
Therefore, the I-18 has the rudders and boards that came off the designers computer as THE correct configuration.

So, if we now switch the basis to the I-18, for this is the correct design boards/rudders;

I 18 100%
I 17 ( 160/227) x 100 = 70.46 of the size needed, so current I17 rudders/boards are 30% ish too big.

I 18 100%
I 20 ( 246/227) x 100 = 108.37 of the size needed, so the I 20 current rudders/boards are 9%ish too small.


Someone check these ratios and see if these numbers are good.

I will be honest, and as Tom stated also,. the I 17 rudders do not fail.

I also know from a local I20 racer, that the stock I20 rudders do not do the job.....which is probaly why the retro rudder is now available.

....ok, enough of this stuff, lets just go sailing..

Bill, congrats on the RC30 cleaning up in the Caribbean. Tell the owner to come to St. Croix in Feb 2005.

regards,

Bruce