Hmm...

I've seen the Murray's catalog before. Several months ago when I last started thinking about this project, I called Performance Cat. Indeed they did say there is a bushing or sleeve to fit inside the beam, into which the wing tubing would fit. But I also remember them saying something about it not working because of the bolts. I've just looked at the online nacra manual dated 1991, which shows straps holding the beam to the hull of whatever model they used. But a later catalog online shows a newer version of whatever to have the same type of through-the-beam bolts I have. So it's probably a good time to have a chat with them again.

I imagine it would be hard to make a sleeve with my bolts going through the middle of the beam. Do you have any suggestions?

Also, with the wing tubing on top of the beam, how would this cause stress to crack the deck? Downward force would be spread along the beam. Upward force on the inboard fitting would be taken by the beam, since it's connected only to the beam. Upward force on the 2 outboard bolts would be transferred likewise to the beam.

Cheers,
Danno