Windsurfer mast for Hobie AI project...

I got a cheap (sub-$200) windsurfer mast that is in great shape and is exactly the same length as my AI mast. I bought the mast base and collar from Hobie, and installed the base (a little Goop and a couple of rivets did the trick).

All that remains is to glue the collar to the mast. However, the windsurfer mast seems to be slightly skinnier in diameter (1mm or less) than the official Hobie mast.

On the Hobie forum, they say to use West Systems G/flex epoxy (which I've got) and not to rivet it, as it could create a weak point. The collar is subject to a lot of turning force, due to the roto-furling sail (and even more so with my mast topper and 2nd sail). The slight difference in diameter means that the collar is ever-so-slightly loose and wobbly, and I think this might make it more likely to break free when attempting to furl the sail (this happens on rare occasion with the standard mast, as reported on the Hobie forum).

I'm wondering if anybody has any suggestions on how to get the collar perfectly centered and how to glue it so that it's less likely to break free. I was thinking that adding strips of fiberglass might help, but also worried that it might just bunch up when trying to slide the collar over the wetted-out cloth...

Just brainstorming here... but I'd find a piece of pvc that's just smaller inside diameter than the outside diameter of the mast.  I'd chuck it up on a drill (for pvc I usually make a quick jam chuck from a dowel with a lag screw in it) and sand a taper on the end.  Then split the pvc down the length on the table saw.  Now you have a sleeve that will fit over the mast and can be used as a centering jig. work some epoxy in the open end, but just enough to lock it in place (maybe a dab here and there).  Remove the centering jig and epoxy the entire void.

Why not lay up a band of fiberglass with resin where the collar will go, let it set up and then sand down to the diameter you need? The band will add a little strength to the area around the collar and you should be able to get a nice, tight fit. Just a thought.

Cheers,
Brad

However, the windsurfer mast seems to be slightly skinnier in diameter (1mm or less) than the official Hobie mast.

Windsurf mast are design to flex at the tip of the mast, to create a foil in the sail....

Why not lay up a band of fiberglass with resin where the collar will go, let it set up and then sand down to the diameter you need? The band will add a little strength to the area around the collar and you should be able to get a nice, tight fit. Just a thought.

Cheers,
Brad

After thinking about it more, this seems the simplest. The only difficulty might be keeping it even all the way around, so that the collar stays centered. Gotta think about it a bit more...

Seems a combo of the 2 suggestions would yield good results. Lay up your fiberglass band where you need it and if you can manage to chuck the mast up, sand the fiberglass/epoxy down in a rotary fashion like its on a lathe. A little redneck engineering to stabilize the length of the mast while it rotates on the drill and I think you'd get a pretty good fit.