On Mon, 27 Mar 2006 20:12:44 GMT, "Roger Long"
wrote:
Does anyone have any direct experience with how well 5200 sticks to
old but cleaned up fiberglass?

I have to put a new backing block in for a through hull in a very
awkward location. Since it’s a Signet Knotlog, it has to be flush and
there isn’t much back up in the taper for a direct hit on some
floating object. I’d like the back up block to be actually backing it
up.

Building up with fiberglass and epoxy working through a hand sized
opening is going to be tough. I’m wondering if a larger than normal
sized plywood backing block done with 5200 might not be nearly as
strong.

I had a pair of Signet transducers on my old Cal-34 with no backing
blocks at all. I'd estimate the fiberglass thickness at about 3/8 in
or perhaps slightly greater, taper was about half the thickness as I
recall. Never had any strength issues.

That said, 5200 is tough stuff and would probably be fine.