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Old 13-04-2016, 11:15   #1
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Polycarbonate or Acrylic for Windows

I have a new to me Manta 40 with front windows that are approx 36" x 36". They are 3/8" acrylic. One side is cracked the other is leaking and needs to be rebedded.

During the buying process, it was suggested they should be replaced with polycarbonate.

Is there an advantage to staying with acrylic?

Thanks,

Steve
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Old 13-04-2016, 15:58   #2
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Re: Polycarbonate or Acrylic for Windows

Acrylic is UV STABLIZED, not sure about polycarbonate.
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Old 13-04-2016, 16:22   #3
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Polycarbonate or Acrylic for Windows

There are certain polycarbonate qualities with a UV-protection surface layer. I bought a pane of that some time ago but still haven't got to replace the previous, non-UVprotected polycarbonate windows that after about eight summers are quite milky in appearance. The UV damage came even quicker for the non-protected polycarbonate than for acrylic but at least they don't craze the way the acrylic did so it supposedly does not affect the strength, which is nothing short of amazing compared to acrylic.


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Old 13-04-2016, 16:33   #4
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Polycarbonate or Acrylic for Windows

By the way - I was told that even polyurethane construction glue, which clings tenaciously to most materials, gets just a weak grip on the protective layer so the dealer who sold the sheet recommended me to sand the layer off from the areas where I need Sikaflex to bind to the polycarbonate. Perhaps he even mentioned a solvent that also could take it away but I can't really remember what now. Also seems more of a difficult to control what surfaces should be untouched.


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Old 14-04-2016, 09:02   #5
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Re: Polycarbonate or Acrylic for Windows

Have had experience with both. Next time it will be glass.
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Old 14-04-2016, 09:25   #6
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Re: Polycarbonate or Acrylic for Windows

I agree with the glass option - replaced our poly-carbonate with a mar resistant surface which delaminated in the tropics and then crazed badly with 1/4" tempered glass 17 years ago and are happy with the choice. We did put a security film on the inside to contain broken bits but even direct impact from a wildly thrashing reaching pole had no effect on the glass.
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Old 14-04-2016, 09:32   #7
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Re: Polycarbonate or Acrylic for Windows

If have used both and believe polycarbonate is worth the extra price. It resist sunlight much longer.

Mine is not glued but fastened with screws. It can be easily removed and reinstalled. I of course drill holes a bit larger than the screw and use hypalon washers I make myself. The rubber seal should be protected from the sun by painting a surface of the clear panel.
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Old 14-04-2016, 09:56   #8
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Re: Polycarbonate or Acrylic for Windows

Polycarbonate is much, much stronger and resistant to cracking. Well worth the extra money over acrylic.
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Old 14-04-2016, 10:14   #9
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Re: Polycarbonate or Acrylic for Windows

Our shop uses sheets of all three materials, glass, acrylic and polycarbonate on a regular basis.
Given the use as a large front window of 36" x 36", glass is subject to damage as it breaks easily unless you use a custom laminated glass which can be quite a few dollars. Even with laminated safety glass, I would not feel safe for two reasons, one has to do with the constant impacts that the glass goes through. The other is that today thieves are in every nook and corner. Short story, glass breaks to easy.
The same with Acrylic. In our shop we generalize the strength factor of acrylic as being seven times stronger than ordinary plate glass. With the impact problems, the material is more liable to crack at the fasteners unless installed by someone who is knowledgeable about the property of acrylic.
So that leaves polycarbonate. Its almost bulletproof and by far a more superior material, but it is also flexible, ( which can be unnerving when you see a large sheet flexing and bowing under severe impact.) Poly is also not so UV tolerant as it will cloud and turn yellow after a few years if not treated.
If you go the poly route, go to a plastic supply shop. You will get a much better price and many shops will cut and finish the work for you for a minimal fee.( )
If you take a piece of glass, a piece of plexi and a piece of poly and use a ball peen hammer on them, you gonna have a tired arm before the poly goes.....
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Old 14-04-2016, 10:43   #10
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Re: Polycarbonate or Acrylic for Windows

Quote:
Originally Posted by akkebeng View Post
There are certain polycarbonate qualities with a UV-protection surface layer. I bought a pane of that some time ago but still haven't got to replace the previous, non-UVprotected polycarbonate windows that after about eight summers are quite milky in appearance. The UV damage came even quicker for the non-protected polycarbonate than for acrylic but at least they don't craze the way the acrylic did so it supposedly does not affect the strength, which is nothing short of amazing compared to acrylic.


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so I don't have to write the same thing.
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Old 14-04-2016, 14:34   #11
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Re: Polycarbonate or Acrylic for Windows

Quote:
Originally Posted by waterdog View Post
I have a new to me Manta 40 with front windows that are approx 36" x 36". They are 3/8" acrylic. One side is cracked the other is leaking and needs to be rebedded.

During the buying process, it was suggested they should be replaced with polycarbonate.

Is there an advantage to staying with acrylic?

Thanks,

Steve
Go with glass if you can Steve.
The glass in my boat still looks good after 30 yrs.
Polycarbonate scratches very easily , acrylic crazes .
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Old 14-04-2016, 15:06   #12
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Re: Polycarbonate or Acrylic for Windows

Thanks for the replies.

Much as I would love glass, these windows have a bend in them and a camber spar, which if carelessly dropped, would be more or less the same as hitting the window with a hammer.

I think polycarbonate is the winner here.
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Old 14-04-2016, 15:12   #13
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Re: Polycarbonate or Acrylic for Windows

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Originally Posted by waterdog View Post
Thanks for the replies.

Much as I would love glass, these windows have a bend in them and a camber spar, which if carelessly dropped, would be more or less the same as hitting the window with a hammer.

I think polycarbonate is the winner here.
Is it a bend or a curve ,Steve ?
Tempered glass does curve quite a lot and does take a lot of knocks.
Does your camber spar hit the windows on a regular basis ?
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Old 14-04-2016, 15:41   #14
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Re: Polycarbonate or Acrylic for Windows

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Is it a bend or a curve ,Steve ?
Tempered glass does curve quite a lot and does take a lot of knocks.
Does your camber spar hit the windows on a regular basis ?
I think you mean safety glass with the membrane. Tempered glass checks and shatters, used in auto back windows. If one goes finding the shards is almost impossible.
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Old 14-04-2016, 15:58   #15
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Re: Polycarbonate or Acrylic for Windows

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I think you mean safety glass with the membrane. Tempered glass checks and shatters, used in auto back windows. If one goes finding the shards is almost impossible.
I stand corrected.
Even so, after thirty years and still looking as good as new I know which material i would use .
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