Plexiglass into fiberglass frames??

[qm]

My daughter asks me about the remedy for leaking windows on their centercockpit ketch(she has two little ones). She thinks they couldn't clean up the fiberglass(?) frames enough for the silkaflex to work and three windows still leak(they had to put a tarp over). So Dad the old boat carpenter, trying to be as helpfull as possible when a half a world a way and long out of the center of action, tells them to go for using 3m5200 even though he remembers removing that stuff from window frames, when it didn't work. What should they do is the obvious question?? Will it all work? Or should they try to clean up better and use silkaflex again?

[Bob Cleek]

If the plexiglass is set into fibreglass frames, I assume the boat is fibreglass. Given that, the proper repair is to remove the trim and windows, clean out the old bedding (caulking) and rebed the plexiglas with a suitable sealant. Then replace the trim rings.

5200 will be extremely difficult to replace. If there is a trim ring that will protect the seam from the sun's UV rays, a good clear silicone sealant should work well.

Essentially, it is an exercise in disassembly, and reassembly with new sealant. Just smearing more good where one thinks the leak is coming from isn't likely to solve the problem.

[ 08-29-2005, 08:55 PM: Message edited by: Bob Cleek ]

[J. Blazy]

What Bob said - ditto. Its no problem to bond to roughened fiberglass with any good sealant, but bonding to the plex requires roughing up the plex and solvent priming the surface. Use PVC cement on the Plex (acrylic sheet) immediately prior to bedding it in sealant or polyurethane adhesives (like 5200 or PL Premium). This is a wet-on-wet process that works like a dream - full solvent weld to the glue due to the PVC cement temporarily melting the acrylic surface.