I bought an old Hobie too. The Pylons were so worn, they were like beer cans themselves, and the bolt holes were elongated. I made little plugs from some sheet plastic and then filled the top 6" or so of the pylons with epoxy and dense filler. I put new aluminum tubes in the pylons to form the bolt holes. Before I put the cross bars on (I had already cleaned, riveted and epoxied the corner castings to the cross bars) I greased the inside of the corner casting with a good quality bicycle grease, kind of like greasing a cake tin. Then I put epoxy mixed with dense filler on the plyon, and put Saran Wrap over that. Finally I tapped the corner castings down over the pylons, squeezing out some of the epoxy. This created a perfect fit but also broke the bond between the epoxy and the corner casting, so some day someone can remove a hull when the need arises. I'm still learing how to sail this thing, but structurally, she's solid. I, too was careful to square up the hulls before the epoxy set.