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voxxmd · 13-06-2013, 14:26

We recently acquired a sailboat from 1977, and I'm willing to bet that the extremely crazed and leaking acrylic portlights are the originals....

Okay, so I've read a gazillion threads on replacing surface-mounted (frameless) lights, and I'm pretty much set. I'll be copying the existing acrylic size (7.5"H x 24"W) and bolt-hole pattern. The windows have been/will be attached to the cabin with binder posts. The cabin trunk in this area is simply fiberglass (not cored) about 1/4" thick. One thing I WON'T be re-using is the L-shaped gasket/trim (vinyl, I think) that trims the rough edge of the opening and also extends about an inch beyond the opening on the cabin exterior to form sort of a spacer/gasket between the cabin exterior and the lens. I'm going with the Dow 795 sealant, and "floating" the acrylic lens by putting O-rings on the screws between the lens and the cabin exterior (and oversize screw holes in the lens).

Questions:

1. I'm planning to use gray-tinted plexi, and for aesthetics, thought I might try having the screw heads on the exterior either black or covered with black. Instead of S.S. Oval-head screws with finishing washers, how about using black anodized aluminum screws with pan heads w/black nylon washers? I know, I know, aluminum is half the tensile strength of SS, but hey - we're just snugging these screws up, not putting any high torque on these! Another option might be to use pan heads (aluminum or SS) with those little black plastic hinged pan-head screw covers. It would seem to me that either of these options would allow for more "float" than using SS finishing washers - they might have more "grip" on the plexi and inhibit movement rather than acommodate it.

2. I'd like to have a beveled edge on the plexi. Is this something better done at a plastics shop, or is it relatively easy as a DIY job?

3. Any thoughts on grey tinted vs clear?

4. I'm removing one of the existing windows to use as a template. Got a piece of clear plexi from Home Depot to temporarily replace the removed piece, and try out my hand at cutting plexi. Since I'm hoping to be back with all the final lenses the following weekend, can someone recommend a "temporary" caulking material that will come off easily after a week or two, yet seal out the rain?

Roy M · 13-06-2013, 15:50

Before you go too far, contact Mark Plastics (www.markplastics.com/‎), 951 735 7707. They supply the complete package for many boats. They bought the company that used to supply many of us our replacements. Good folks.

I've built my own windows, and replaced them about every fifteen years, on my third set now after 35 years. I use the darkest acrylic possible because of the glare and UV. It's a lot of work to make them clean and leak proof. I cut with special blades, then flame polish the edges, then seal them with 3M 4000UV, and sandwich them between mating finish rings (hand made). Did I say they take a lot of time to fabricate?