Glassing over large ports.

[Geoff16659]

Pearson 323; plan to glass in the long fixed ports (2 openings, apprx. 7x28") and cut out for 3 new ports, (4x16 NewFound Metal) Need 1/2" or more of coach roof wall to mount new ports. presently have roof/side fiberglass 3/16" and inner liner about the same. Considering putting 1/4" plywood between the 3/16" coach roof and inner liner to make a sandwich. I could slide the plywood between the coach roof and liner for the entire length of the coach side wall, thus closing the openings and giving a base to apply the fiberglass to and then glass over it. Would this work OK? Is it too complicated for a neophyte? ThanksGeoff

 

[ex-admin]

Modifying cabin top port openings

This should be a relatively easy modification using the technique described as long as you have access to the entire area where the plywood will be bonded in. Assuming so, once the old ports are removed and the liner out of the way you should sand the inside cabin top surface where the plywood will be bonded. Also sand a bevel (about 8:1) on the outside around the circumference of the ports. It would be a good idea to coat the plywood with 2-3 coats of epoxy, allow it to cure, and sand the surface that will go against the cabin top. Mix some 105 resin and 206 hardener and brush some on the cabin top surface, add some 406 colloidal silica until you have a mixture like mayonnaise, spread this paste on the bonding surface of the coated plywood and clamp/secure in place until cured. Clean up any squeeze out from the beveled surface. Laminate in fiberglass patches using our recommended techniques, which it sounds like you know. If not, refer to the letter in this forum about repairing machined holes for a more detailed explanation, or reply to this submission.

 

[Geoff16659]

I don't have access to the inner side of the coach

roof unless I cut out a great deal of the head liner. I can slide plywood into it but I can not get a hand in there and sand. I don't know how even i can keep the epoxy on the plywood surface but can not apply it at all to the cabintop surface except for an inch or so inside the present ports. Will it still work? Perhaps only as a support for the fill in patches? The patch openings are 28" long.Thanks for your time and help.Geoff

 

[Bruce Niederer]

Another option

Since you can't get to the inside bonding surfaces you will have to create a backer that you can insert from the outside. First, grind an 8:1 bevel around the circumference of the existing port openings on the outside. Reach inside the edge of the openings and sand as best you can. Then wet out a piece of fiberglass on a sheet of polyethylene plastic and allow it to cure. Make it large enough so you can cut 2 backer plates about an inch larger than each port opening. Once cured, use sissors to cut the backers to shape, sand a bit around the outside edge of each. Drill a couple small holes side by side centered along the length of the backer. You'll probably need 2 or 3 pairs of these holes. Run a long twist tie or pipe cleaner through each pair of holes so the loose ends are equal and facing out to give you something to pull the backer against the inside surface with. Then use our 5 minute epoxy G-5 and put some all around the sanded edge of the backer and put it through the port opening and secure it against the inside surface. It will be flexible enough to bend it so it will fit through the port opening. Use the twist ties like handles to pull the backers tight to the inside surface. You can use a stick or scrap to twist the ties to and hold the backer in place until the glue cures - about 10 minutes. Then laminate in the patches like I described in my original posting.