Plexiglas vs lam Glass

[poopdeckpappy]

I'm rehabbing my windows and I was wondering what others have used when replacing the windows.

I was leanning towards the 1/8" laminated which is what is there now, but, I'm hearing Plaxiglas is the way to go, stronger and lighter than lam glass, which is fine but, I'm worried about discoloration and scatches.

Anybody gone with plexiglas ?? and how does it hold up ??

Thanks

Poop

[hellosailor]

For what kind of glass?

There's no contest, in that laminated glass will be nice and clear and unscratched compared to plexi. And if the plexi part of it is the same thickness, it will have at least as much strength--but a higher price.

There's probably glass laminated to polycarbonate to give you the best of both worlds but I'd hate to guess the price.

Ordinary good plexi, or lexan, when properly mounted (so it doesn't craze from stresses) and when properly cared for (no petroleum products allowed to contact it) does a good enough job for many applications, but I wouldn't use it on the picture windows on Sequioa.

Remember that "plexiglass" is about as specific as saying "wood" or "metal". It comes in all grades, and the cheap stuff at the hardware store won't be the most UV-resistant, the hardest, or the best in any other way--besides cheap.

[sailingdog]

Depends on the boat and whether you intend to go offshore at all. If you're going to go offshore at all, you would probably want to get heavier material than 1/8".

Laminated glass is fairly strong, but impacts, like dropping a winch handle on them, or getting hit by a flogging shackle will generally crack the glass, and leave nasty splinters.

Personally, I would go with Plexiglass (acrylic) or if you want more strength ABS (polycarbonate or Lexan).

Both materials come in different grades and with different coatings on them. The acrylic is slightly better in terms of resisting UV, but the ABS is stronger. Both can come with UV-protective finishes as well as scratch resistant coatings.

If you're going to do the work yourself... a good source for it, that will probably be less expensive than many others is to find an industrial sign supply company. That's where I got my ABS for new drop boards at about 40% off of what the glass companies would have charged me, and about 66% off of what it would have cost in the marine chandlery...

[poopdeckpappy]

Thanks Guys, I just returned from a glass Co. that does work for us and you're both spot on, Lexan or Ultra High Molecular Weight Polyethylene is the material to use, both are being used in boat windows and hatches with the UHMW being a little better in abrasion resistants

I'm stuck with the 1/8" thickness as I'm refinishing the orginal frames, but even 1/8" lexan is a strong as and maybe stronger than 1/8" lam glass

And yes Saildog, we will be offshore, so if you all think that 1/8" lex is good, then that's what Im going with.

Windows range from 6x19 to 4x16

[hellosailor]

Pappy, there are grades of Lexan like GE's "MR-10" which have a scratch-resistant film on the exterior facing side. That will bump up your cost, but add scratch resistance.

For plastic glazings, one way to keep them looking good is by using a fine grade plastic polish (like Novus "fine" grade) on some regular basis, before you notice any change to the surface. And resist the temptation to mount them "extra secure" in the frames, the plastic must be allowed room to expand/contract per the maker's specifications--or it will develop stress crazing, too.

[SmartCaptain]

Hi Pappy,
One more thing to consider - saltwater intrusion around the edges of laminated glass can cause it to "fog". I have a 1988 Island Packet with several fogged portholes. I decided to go with 1/4" Lexan as the replacement material.

I must admit that one big factor in the decision to go with Lexan was the deal I made with the local glass shop to trade a case of beer for pieces of scrap Lexan - a lot cheaper than paying for the laminated glass! I also have spare pieces should one become scratched.

If you use Lexan, pay attention to the paper cover. Mine indicated that one side of the Lexan was the "exterior" side that faces the sun. Guess it has some sort of UV protectant on that side of the Lexan.

Hope this helps,

Jeff

[sailingdog]

Yes, the exterior side is the one that is usually coated for UV and Scratch resistance.

[hellosailor]

Jeff-
If you have an "architectural grade" Lexan like GE's MR-10, yes, there is in fact a laminate applied to one side only which provides extra scratch and UV protection.
I guess laminated glass should have the edges epoxy-sealed before marine installation, I didn't know the laminate was susceptible to breaking down.

[Freesail99]

A friend of mine swears by the gasket material used by the auto wind shield people. It remains semi soft. I don't recall the name. He says it makes a great bed and has been 100% water proof .....

[sailingdog]

Freesail-

It is probably a butyl rubber based sealant, which is pretty common for auto windshields. It usually comes in tape form, and is pretty straightforward to apply. I don't know how well it resists salt though..