I have some intrest also for my Nacra 18SQ. Really I have thought about making Deeper, slightly more narrow rudders for the SQ meter, maybe even with with Ts on the bottom, like the Stealth. If you consider making some boards, I also would like to know. I do have extra Nacra blades that I could ship you if you need a template.
Steve Slagle
N5.5U - 18SQ