Hi, new member here.

I recently purchased a Nacra 18 sq. and have noticed on some videos that there are people running set-ups without link arms between the cross-beams. I am wondering how it is possible to run a set-up such as this, given that the front cross-beam, it seems, would be free to rotate.

Also, I would like to make my own fins and was curious to know if there are some models available that I could use as a guideline. I'm sorry if some of the terms I used aren't quite clear, I am from Quebec and there doesn't seem to be a good translator available for technical terms.

Thanks in advance to anyone who can provide help.

Hi, for the "link arms" I recall that the NACRA guys used to put rivets in to hold the beams and straps to stop the rotation. (it was one per corner, but I think you would be better off with two per corner.)

And yes you should consider new boards, after the mast those centerboards are the heaviest parts on that boat
I'm sailing an A now and use CB that are 130 X 15 cm so if you subtract what's in the hull they are 90 X 15 cm (in the water) with an aspect ratio of 6:1 .
Any thing with an A/R of more then about 6:1 and you might run into torsional stiffness issues.
you should consider a little larger boards seeing as you have another 43 feet of sail area.

Also think about a modern square top sail some time in the future.

good luck

Les