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liveincolor 03-24-2012 01:47 AM

Replacing Leaky Windows
Apologies if this post has been made. I searched, but it seems as though it hasn't been covered in the manner I'd like to read. If it exists you may refer me to it.

My two priorites are eliminating leaks, and doing so as cheap as possible. Here is are my initial thoughts going into this project, I'm sure you guys will have some insight and opinions to help make this project more successful.

Through research I think I've narrowed down window material to either Lexan (polycarbonate) or Pexiglass (acrylic). Initally I was leaning towards polycarbonate because I was under the impression it would be easier to cut-to-shape with a fine tooth blade and a jigsaw. Is that the case ? I intend to do as much as possible myself, but would obviously conceed to the pro's if it otherwise means wasting material by chipping and breaking. But I also like the idea of a more scratch resistant material like acrylic if it's possible to cut myself. According to research it seems both can be cut by the DIYer. Can anyone recommend a supplier where I can get sheets of either material ?

Once making my mind on a material, I want to use the old windows as templates and make new oversized windows that I will lay in place and drill through the deck to secure using a silicone based compund to serve as a gasket. I'm aware of both materials tendancy to expand and contract so I was thinking I would oversize the drill holes for the screws to allow expansion and use rubber washers. I plan to use silicone compound as opposed to polyureathane to water seal the edges inside and out (I read in a Don Casey article, LifeSeal, a silicone/polyureathane mix, would work well for both seal and adhesion, but the permanence of Polyureathane makes me nervous even if mixed with silicone).

That's it. I'd love to have tinted glass, but feel like the darkness might add to the expansion problem. Do you agree ? Please share your wisdom.

Thanks all.

peterchech 03-24-2012 10:59 AM

Re: Replacing Leaky Windows
Try this article:


I did it following don Casey's excellent book this old boat. Came out great.

Acrylic is more scratch resistant, but far weaker and only a little cheaper. I used screwed in 1/4 inch acrylic because I couldn't find a local source for lexan, but if I were going offshore 1/2 inch through-bolted lexan would be my choice. Check out don Casey's book it gives the formula for hole spacing and distance from the edges. Just make sure you use a really dull drill bit for the holes, and a jigsaw blade that is meant for plastic, otherwise the stuff will crack. Drill the screw holes oversized to allow for expansion. Do not use silicone, use butyl. It is easier to use and lasts longer. A router with a rounding bit will round the edges just fine, then use 400-800 grit paper to get it shiny (if u even care about the edges being shiny).

My ports had been leaking like sives for years, the po never fixed the problem just put a bucket to catch all the rainwater. So the ply core had delaminates and begun to rot around the edges of the existing ports. I cut away most of the rotten parts, so I wound up with oversized ports.

Use tinted because it looks better and keeps the cabin cooler in the summer. It is easier to hide the cut out as well, because you just paint the acrylic black in all areas except where the ports themselves will be.

jrd22 03-24-2012 11:25 AM

Re: Replacing Leaky Windows
LifeSeal is good stuff, but Faster here on SN recommended Dow Corning 795 when I was re-sealing our windows and now I wouldn't use anything else. Fantastic stuff for sealing poly/acrylic to fg.

Faster 03-24-2012 11:30 AM

Re: Replacing Leaky Windows
I have done the paint thing...but more recently have spreading a layer of black DC795 to create the same effect and a better seal. Use the darkest acrylic for best effect. However you end up attaching the lens be careful not to overtighten.. Leave a "gasket" layer under the lense.
Good luck - and don't forget to mask everything inside and out to ease cleanup and for clean finished look.

liveincolor 03-24-2012 02:36 PM

Re: Replacing Leaky Windows
You guys are great ! Thanks, very helpful indeed. I'm happy the tinted acrylic came recommended. Can anyone suggest a supplier, or perhaps a store that might carry it locally, like a Home Depot of sort ?

ambianceack 03-24-2012 06:02 PM

Re: Replacing Leaky Windows
consider using butyl tape as the gasket. I would also recomend using 4200 for below the waterline. yse I know your portlights are above water but when it is blowing like **** ,raining and the decks are awash it might seem like you are under water. Also, Captain tulleys is also helpful once everything is in place since it helps to seal tiny gaps, if present. We rebedded our portlights about two years ago now and seem to be rock solid.

mitiempo 03-25-2012 01:40 PM

Re: Replacing Leaky Windows
Here's a link to a comparison between cast acrylic and polycarbonate by Select Plastics, the largest marine hatch restorer in the world. Acrylic -vs- Polycarbonate

Tony knows his business very well and recommends cast acrylic which all major hatch producers also use.

Dow 795 or Sika Flex 295 UV are the adhesives of choice.

Cast acrylic will outlast polycarbonate by a large margin.

JanetGroene 03-25-2012 01:43 PM

Re: Replacing Leaky Windows
Don't overlook the fact that water from previous leaks could have channeled long distances within the boat. When you get the old windows out, make sure there isn't rot in unexpected places. Good luck.

Sailormon6 03-25-2012 02:04 PM

Re: Replacing Leaky Windows
I had mine replaced professionally, but was thinking about doing it myself, and found that different types of plastic sheet goods can be bought at a substantial savings on Ebay, and some of them will even cut it for you, if you provide them a template.

liveincolor 03-26-2012 10:59 AM

Re: Replacing Leaky Windows
mitiempo, thanks for the article. Great info there.

JanetGroene, great point. I'll be on the lookout. My entire deck is solid fiberglass so I think that will be beneficial to me, but I'm not exactly sure how strong it will be against rot, I imagine more so than woodcore or similar construction. Guess I'll find out.

Another good tip, thanks sailormon.

Love these forums. I'll try to photograph and document the project in a post when I complete it. Hopefully will be able to start and finish before the end of April. Thanks again everyone.

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