Advice please on glassing over fixed portlight openings

[rbhb2]

Hello everybody, I have searched previous posts but have not found anything describing techniques for glassing over large fixed portlight openings. For strength purposes I am considering glassing over the saloon fixed portlight openings and installing either NFM or Manship 7x14 opening ports. The original portlights consisted of the plexiglass sandwiched between two anodized frames that were screwed together. The cabin sides are constructed of an outer layer and an inner liner separated by about 5/8" (not cored). However, the outer and inner layers are pinched together between the frames, resulting in a rather vulnerable cabin side. I would appreciate suggestions, advice or war stories about glassing over the openings. Links and pictures would also be welcome.

[s/v Faith]

Here is a reply until a better one comes along.

I think that the stabilization of the cabin liner and the cabin top will be important. To this end I would be tempted to establish a standard 'gap' between them of something like 3/8" all the way around (you will see what will work best, if the liner is bulging too far make the gap smaller... Use something like slices of teflon kitchen implements... so you can keep the gap open ans still remove the wedges after the filler sets.

I would fill this gap with wet out kitty hair kitty hair, and pack it in there firmly. Once it kicks, I would grind the outer edge in at a significant taper, and then screw a light wooden panel over the opening and start my buildup with mat and cloth....

Ought to be good and strong.



Hope you will be happy with the new look, might want to cut the ports out of cardboard and tape them up to be sure before you start.

[Figment]

or buy some 1/4" G10, cut to fit, goo in place, proceed with a lot less laminating and subsequent fairing work.

S&S 35???? We need pics!

[Quetzalsailor]

Be sure that you'll be happy with the appearance. Mock it up with white cardboard and a cutout.

Boat lust is a very important emotion and it's best to have it satisfiable each time you row away, particularly after an engine failure or boiling hot flat calm day!

[Chris Campbell]

I have the same project to do, and similar construction details to work with, so I'm glad for this thread. I'm also glad for the suggestion to get a piece of G10 to glue behind the opening - that might just be the ticket. I had been planning to patch it the way you patch any hole - bevel the edges and lay cloth over it, but I have been somewhat concerned about it drooping, of course. I guess just doing it will tell if it'll be a problem...

I have the same liner, spaced away from the cabin side. I think there used to be a plywood spacer in there, since I found it around a couple of the windows, but not others. Obviously couldn't stay the course while the windows leaked on it... My plan for this is a bit more work, but I think will produce much nicer results: cut away the liner and replace with 3/8" plywood (or 1/2" if you're feeling really robust), epoxied to the cabin side. That'll be much stronger, and much nicer to mount windows in, and - you get to pick your choice of inner veneers, and after varnish dramatically improve the look of your interior (in my opinion, at any rate, I've never been a fan of overly plastic interiors).

Funnily enough, despite having been mulling this over for months (what else do you do when you can't work on your boat? Think about working on your boat!), it's only just occurred to me that if I epoxy the plywood in place first I'll have a much easier time glassing over the hole from the outside, since I'll have the plywood to lay it up against...

Good luck with your job - let us (especially me) know how you do it so we can benefit from your experience!

Cheers,

[tpl]

> S&S 35

known are S&S 33, 34, 36, 37 and 38--but 35? tell us more

[stone]

On my boat S&S 30 (1965 Chris Craft) I removed the inner liner on the inside and glued a piece of 1/2" thick marine ply to the side.(running the whole length and width of the cabin top) I used thickened epoxy held in place with screws on the outside . After the epoxy had kicked I removed the screws and glassed up on the outside with un-waxed resin and did my final fairing with microballons in waxed resin. My plans are for three small fixed ports on each side.

[Zach]

You may want to study the cabin sides to see what sort of curve they have. Most cabins have a light curve along their length as well over the height... making a stronger structure.

My two cents is to back fill the gap between the two skins with chopped glass, or cotton fiber and epoxy resin. When that has cured, grind it back to a bevel larger than 10:1 so there aren't any lumps where the glass starts.

Take a piece of 1/8th inch marine grade plywood and warp/bend it to the outside of the cabinsides holding it in place with some big fender washers and square drive self tapping screws. Glass it from the inside.

You can save youself some work by rolling a coat of kilz, or heavy enamel, or spraying some heavy epoxy paint on the plywood... then sanding it flat to 100+ grit. Spraying or rolling a coat of poly vinyl alcohol mold release over some meguires gold car wax, or some real mold release wax depending if you can get your hands on some. West marine carries PVA, but you can buy a gallon for the same price as their little bottle. Spray 6, 7, 8, 9... 10 coats waiting for each to tack up between. Brushing PVA sucks, as it sets up pretty quickly and a high spot on the form is a low spot on the glass. Spraying it is 10 times better... don't thin it, just shoot it at a fairly low pressure and a 4-6 inch spray pattern. If the portlight is smaller than a roll of aluminum foil is tall, you can spray contact cement 3m 77 in a real heavy coat and work any wrinkles out with a plastic body spreader... then following up with a coat of wax and PVA. The instructions say a light coat on both surfaces... but if you really hose it on it'll give some open time to work out the wrinkles. Saves time on painting and sanding. Lastly, you can stretch a piece of 2mil polyethylene plastic over the plywood... but it tends to wrinkle and stick to the epoxy in places.

Cheating, is to go get a sheet of white melamine faced hardboard from the hardware store and wax it... but it doesn't bend quite as fair as thin plywood.

Glassing it from the inside, with a plywood that has all the prep done to it saves a lot of time on sanding. Since the plywood is thin, it will warp to the shape of the cabin sides, where a thicker piece of plywood or premade fiberglass will not.

When you go to fair it in with the rest of the cabin top, grind the glass back into a slight low spot, then use a foot or two long sheet metal drywall taping knife to pull from the original gelcoat sides along the length of the boat with a fairing compound of your choice. That can mean cabosil and microballoons in epoxy, awlgrip awlfair, alexseal's grey fairing compound, or system three's silver tip... Any of them will work nicely.

From there long board from the edges in, lightly with 36 grit... any spots that show themselves at lows, add a touch of filler. Think about it like you would a clock... start out at noon, work in... then 1:00... This will leave a highspot in the middle. From there cant the board at a 45 degree angle to the length of the boat and work up and down along the cabin top until you can't see or feel anything.

From there roll or spray a primer, with a dusted coat of cheap black or blue enamel paint. If you are in a rush, use green food coloring in alcohol over the white primer... just wed down a rag with it and wipe the surface. Food coloring doesn't gum up the sandpaper near as much as cheap enamel. When you sand it with 80 grit or there abouts... the low spots will show themselves. From there either spray it with a cup gun or use a little hot dog foam roller and touch them up. Spray a coat or two, come back in a few minutes... spray or roll another coat. You are building out in mils of thickness. If you keep sanding to keep everything flat, you'll end up with a depression/low spot... So a reasonable level of perfection is what you want to shoot for. If you can't feel any swoops, loops, or lows through a piece of paper or a shop rag, spray it in primer and keep on moving!

Have fun... 90% of its prep work on the form that spans the gap... the rest is sanding. Don't be afraid to sand down below the surrounding surface and fill it back up. It's a lot easier to sand fairing compound than it is to sand fiberglass. Localized highspots in fiberglass show low spots in a donut shape around them when it comes time to paint... When in doubt... hit it with more primer, or skim it again in compound.

Zach