What About Plastic?

Plain tempered glass is great for looking through, but unless it’s laminated, it’s too susceptible to damage for my liking, especially for hull windows in a yacht that’s designed to, as they say, “go to sea.” Even minor damage can occasionally lead to shattering, as has happened in high-rise buildings in Chicago, Toronto and Austin. (Experts opine these events resulted from edge damage to windows that went unnoticed during installation.) Tempered glass, however, is used for hull windows in thousands of yachts these days, and unless I’m missing something, not many are going to the bottom from glass failure. Nevertheless, I’d choose stronger polycarbonate for my hull windows and deal with its disadvantages.

Polycarbonate, of course, is nearly indestructible and many times more impactresistant than tempered glass—anywhere from 20 to 50 times as resistant, depending on whose numbers you use. You can beat it with a sledgehammer and it won’t break. It’s half the weight of glass of comparable thickness, which makes it easier to install and puts less stress on the adhesive, and maybe saves a bit of fuel, too, if you have lots of windows on board. It can be cold-formed—many hullside windows are curved—and is resistant to cracking. Only thing is, it’s not as clear as glass, it’s much easier to scratch and it can turn yellow after years under UV rays.

But on the other hand, polycarbonate is less expensive and can be worked with normal tools, so replacement is easier if the window gets too yellow for your taste. I lived in crew’s quarters under a polycarbonate hatch on a sailboat for four years, and I never saw any yellowing—so in my book, yellowing’s not a concern. I never managed to scratch the thing, either, even though I dropped stuff on it with some frequency.

What about acrylic? It’s not as strong as polycarbonate, but it’s still stronger than tempered glass. It’s clearer, too, almost as clear as glass, more abrasion-resistant and stands up better under UV light. Moreover, small scratches and abrasions can be polished out. And while it’s stiffer than polycarbonate and therefore more apt to crack or chip, it can be a good choice overall for ports in the hulls of smaller boats not meant to go to sea. Plenty of deck hatches are made with acrylic, too, and they seem to hold up fine.