Emotionally, I can’t take this anymore. (Windows)

[Chotu]

Originally Posted by delmarrey

Go to my blog and see what I did. It worked out really good. The outer sealant, I did have to touch up while it was in the San Diego sun.

And make sure to use the proper sealant.

I’m not seeing a link to your blog. Definitely looking for it.

[belizesailor]

Originally Posted by Chotu

It’s bending in this Fn heat.



The old stuff is right next to it in the pics. It expands and contracts like crazy but doesn’t bend in half.

Most plastics have big thermal expansion factors. You can screw and glue it, but you must oversize the screw holes to account for thermal expansion.

Ive redone the deckhouse windows twice on my current boat...thats over a 20 year period. They are glued & screwed.

BTW the first redo was in Texas and the second in Guatemala. Both as hot or hotter than Florida. These plastic windows have spent thier entire life in hot humid weather and have done quite well. Redo's were due to material getting old and hazy not due to thermal expansion issues.

As others have already posted, research the right adhesive for the plastic you are using.

Shipping in some better quality material may be worthwhile, but it wont eliminate the thermal expansion. Use flexible adhesive and oversized screw holes to deal with that.

Hint: if the seller cant provide full data sheets on the material then move on.

[belizesailor]

Originally Posted by Woodland Hills

This is why you do not see plastic windows on production boats. The expansion is too great for effective sealing. You need to bite the bullet and pony up for high strength glass.

There are plenty of production boats w plastic windows.

[delmarrey]

Originally Posted by Chotu

I’m not seeing a link to your blog. Definitely looking for it.

Sorry! It use to be in my signature.

http://choate-40.blogspot.com/2013_0...chive.html?m=1

[Chotu]

Originally Posted by belizesailor

Most plastics have big thermal expansion factors. You can screw and glue it, but you must oversize the screw holes to account for thermal expansion.

Ive redone the deckhouse windows twice on my current boat...thats over a 20 year period. They are glued & screwed.

BTW the first redo was in Texas and the second in Guatemala. Both as hot or hotter than Florida. These plastic windows have spent thier entire life in hot humid weather and have done quite well. Redo's were due to material getting old and hazy not due to thermal expansion issues.

As others have already posted, research the right adhesive for the plastic you are using.

Shipping in some better quality material may be worthwhile, but it wont eliminate the thermal expansion. Use flexible adhesive and oversized screw holes to deal with that.

Hint: if the seller cant provide full data sheets on the material then move on.

Can you tell me exactly what plastic you used, exactly what adhesive and how big your windows are?

[belizesailor]

Originally Posted by Chotu

Can you tell me exactly what plastic you used, exactly what adhesive and how big your windows are?

First replacement was Lexan with a MARGARD coating. The MARGARD is supposed to provide enhanced UV resistance, but in my case it didnt work so well (there are a bunch of products w MARGARD coatings so YMMV). Within a few years I needed to replace due to greying. Otherwise it was fine, no structural issues.

The second time was with a generic acrylic product. It has held up fine, but is starting to show wear/crazing as acrylic is prone to do.

The windows are large (rear about 2x2', fwd about 3x2'). The forward window also bends around a curve...not enough to need thermoforming, but a slight very wide radius curve.

Its been many years since I did the jobs and I dont recall the specific adhesives used.

You can see the deck house window arrangement in this image:

https://www.dropbox.com/s/tyibymkj61..._1410.JPG?dl=0

The visible fittings around the windows are for the sun screens, which are normally attached. The screws are less visible, but each has a small rubber backed washer to form a seal. Screw hole diameter thru the sheet material is nearly 2x the diameter of the screws.

[s/v Jedi]

It looks like the cut edges of your windows are exposed (as are mine in a similar setup). This greatly accelerates UV degradation because UV rays entering the material from the edges is angled such that it keeps reflecting back into the material from the surfaces rather than pass through.

The solution is to prevent light entering the cut edges by covering them, easily done with a product like black 1-part polyurethane paint.

Originally Posted by belizesailor

First replacement was Lexan with a MARGARD coating. The MARGARD is supposed to provide enhanced UV resistance, but in my case it didnt work so well (there are a bunch of products w MARGARD coatings so YMMV). Within a few years I needed to replace due to greying. Otherwise it was fine, no structural issues.

The second time was with a generic acrylic product. It has held up fine, but is starting to show wear/crazing as acrylic is prone to do.

The windows are large (rear about 2x2', fwd about 3x2'). The forward window also bends around a curve...not enough to need thermoforming, but a slight very wide radius curve.

Its been many years since I did the jobs and I dont recall the specific adhesives used.

You can see the deck house window arrangement in this image:

https://www.dropbox.com/s/tyibymkj61..._1410.JPG?dl=0

The visible fittings around the windows are for the sun screens, which are normally attached. The screws are less visible, but each has a small rubber backed washer to form a seal. Screw hole diameter thru the sheet material is nearly 2x the diameter of the screws.

[belizesailor]

Originally Posted by s/v Jedi

It looks like the cut edges of your windows are exposed (as are mine in a similar setup). This greatly accelerates UV degradation because UV rays entering the material from the edges is angled such that it keeps reflecting back into the material from the surfaces rather than pass through.



The solution is to prevent light entering the cut edges by covering them, easily done with a product like black 1-part polyurethane paint.

They are mostly (except the midships edges).

Hypothetically I suppose, but I last redid these almost 10 years ago. They are acrylic, so the scratches/crazing will get em before the UV does anyway.

[s/v Jedi]

Originally Posted by belizesailor

They are mostly (except the midships edges).

Hypothetically I suppose, but I last redid these almost 10 years ago. They are acrylic, so the scratches/crazing will get em before the UV does anyway.

I read here https://aristechsurfaces.com/pdfs/te...lletin_186.pdf that for crazing to occur, both tensile stress and aggressive liquid is required... not just one of those but both...

[belizesailor]

Originally Posted by s/v Jedi

I read here https://aristechsurfaces.com/pdfs/te...lletin_186.pdf that for crazing to occur, both tensile stress and aggressive liquid is required... not just one of those but both...

Of course on a boat the odds are good to have both...maybe their study is a bit biased toward static land based installation. They refer to the effect as rare, but if you look at acrylic hatches on older boats that doesnt seem to be the case aboard a boat. Its common to see older Lewmar hatch lens crazed...mine certain are.

My windows are still in pretty good shape, not crazing really, just micro scratches from the sun screens (usually in place) and the occassional boat cleaner hitting them with stiff brush before I catch them.

[Desert Dawdler]

What an utterly miserable and frustrating thing to deal with, I wish I had helpful advice but I can only offer sympathy. If it’s any consolation I’ve learned a surprising amount about windows and their construction reading the thread, something I hadn’t previously given much thought to, and will likely find useful in the future (when I get a boat that actually has some).

Please keep us apprised, I’m curious to see how you end up solving this.

[Chotu]

Originally Posted by Desert Dawdler

What an utterly miserable and frustrating thing to deal with, I wish I had helpful advice but I can only offer sympathy. If it’s any consolation I’ve learned a surprising amount about windows and their construction reading the thread, something I hadn’t previously given much thought to, and will likely find useful in the future (when I get a boat that actually has some).

Please keep us apprised, I’m curious to see how you end up solving this.

I will definitely update.

Currently I’m just realizing we don’t have a good material for windows. That’s the issue.

I picked up a sheet of 1/4” tempered safety glass about half the size of just one square is my windows at Home Depot yesterday. Lifted it up. It’s typically used for a shower install. It was so heavy I almost couldn’t believe it.

Then we have polycarbonate and acrylic. Both are awful I’m terms of thermal expansion.

Polycarbonate clouds and scratches easily.

Acrylic crazes.

That’s it. Those are the choices.

Pick your poison and live with it.

It’s awful.

Question: What does the Gunboat 55 or 57 use??

[s/v Jedi]

See how the roof overhangs the windows... 99% of UV damage prevented right there. Can’t see if the edges on the sides are protected though... I wonder if polishing the side edges is enough protection as incoming UV rays under that angle should reflect away I think... unless the sun is close to the horizon but I guess there’s much less UV in that case.

[Chotu]

Originally Posted by s/v Jedi

See how the roof overhangs the windows... 99% of UV damage prevented right there. Can’t see if the edges on the sides are protected though... I wonder if polishing the side edges is enough protection as incoming UV rays under that angle should reflect away I think... unless the sun is close to the horizon but I guess there’s much less UV in that case.

Sorry for not being more detailed. That’s not my concern at all. I’ve had zero issues with UV coming in the sides.

My issues were with heat expansion and contraction and using VHB tape as the adhesive and 795 as the sealant.

It MIGHT work to use 795 as the adhesive, but I don’t want to test this out. No one here has windows as large as I do.

The gunboat pictured does.

So I’d like to know what material the windows are made from and what they use to hold them in place. I can just copy that if I can find out.

[Lake-Effect]

Originally Posted by Chotu

The gunboat pictured does.

So I’d like to know what material the windows are made from and what they use to hold them in place. I can just copy that if I can find out.

.. contact the manufacturer? Contact a dealer?