Actually Syon most of the blue water type ports are made of very thick tempered glass.
New Found Metals,
Spartan Marine &
ABI are just a few of the high quality port manufacturers who use tempered glass and not plastic. I've even been on some serious off shore Sword fishng vessels that have large glass windows and even those are very, very thick tempered glass...
P.S. Most glass shops will also cut Lexan and Acrylic panels..
These ports are glass!!
