Originally Posted by Sanduskysailor
Having sailed far offshore on a pilothouse with large port/windows in the pilothouse here is my take- Lexan- expensive, strong, scratches easily, especially hard to see out of at night. Plexiglass- relatively inexpensive- really not suited for larger expanses since it will flex and blow out when hit by a big wave. Tempered safety glass, stiff, optically good, heavy, will break with hard impact. The boat i sailed extensively on had forward window in Lexan(because of hatch in window) and the side windows were 3/4"" tempered glass which withstood several days of waves crashing over the pilothouse. Good luck with your choices.
While i am not a world sailor but i can tell you a few things about polly carb and plexy, lexan etc..
Lexan is the best choice out of all of them but it is flexible which make it bullet proof has the best uv and scratch resistance and does not crack easy like all the others that WILL shatter.
Would i mount it in my boat? nope.. My track cars? yes..
A pain of double laminated glass will hold far more stress,pressure,and impact than comparable Lexan. On A large impact, the lamination will hold the glass together and still remain mostly water tight "as long as the fiberglass around it also could take the pressure". IE The front windshield of every passenger car is built the same.
You can get them in a tint,green for uv only and will not scratch expand,contract with heat. You can see through them after a year of sun and fun. They are cheaper and can be redone anywhere on the planet as long as you still have the frame.
Even the best polly carb leak due to expansion,and heat. After time the plastic will contract and cause a leak sooner or later. And as with any modification to any thing... it will only be as good as the mounting you use to hold it on.
Through bolting seems the be the most used but the polly will expand and contract so you must notch for such,in doing so you make weak spots all over the place. Which is where cheaper polly windows always fail. Small cracks form and soon a large crack will run out.
Polly carbs must be cleaned with soft water " not salt water" and a VERY soft towel or they scratch terribly.
Its your boat and this is just my experience.
Here are pics of 40 year old glass out of my boat and new triple laminated glass that went in to replace all 4... Cost $ 240 us for all 4..
One good Lexan window in 3/8" will cost you damn near that.
When i carried my new windows down to my boat one fell and bounced down a flight of concrete steps "5 to 6' " while smashed over and over i picked it up and took it back to the glass shop and used it as a template for another one. it was still together and in the same shape/size although busted to hell.
Good luck on your boat.