Thickness/Width/Gauge

Oct 19, 2017
7,732
O'Day 19 Littleton, NH
I'm sorry Plymouth Sailor, I can't answer that question except to suggest it is the wrong way of looking at it. How big is the window? The appropriate thickness for plexiglass should be based on the kind of stress it will experience. A larger opening needs more support from the material that fills it against a perpendicular force such as a wave hitting it. The numerous portlights in my family's 56' schooner were not nearly as large as the one deadport per side in my 19' Mariner. It would take a smaller wave to damage the Mariner's deadport if materials were equal. Of course, I'm far less likely to encounter a big enough wave to crack the window on my Mariner, than on our old schooner.

I can't get to my Mariner under the snow right now, so I can't even give you that comparison.

-Will (Dragonfly)
 
Mar 1, 2012
2,182
1961 Rhodes Meridian 25 Texas coast
My small port in my 25, which is often sailed offshore- are 3/8ths
The Vanguard 32 I rebuilt for a customer had 1/2.

Both lexan, not plexi glass
 

dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
Lexan is a trade name for polycarbonate. Some other trade names are Hyzod, Tuffak, Makrolon, IIRC. If you use polycarbonate, look for UV resistant types. 3/8 and 1/2 inch stuff is mighty tough stuff.

I am also a fan of UV resistant polycarbonate for Windows and such on boats. You could also use cast acrylic, while not as tough as polycarbonate it is inherently more UV resistant. At the thicknesses mentioned, either would be fine in a normal window sizes found on most 25 footers I'm familiar with.

dj
 
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Sep 30, 2013
3,538
1988 Catalina 22 North Florida
The toughness of acrylic and the toughness of polycarbonate are two different kinds of toughness. Polycarb is resistant to sharp impacts such as bullets, where acrylic is more flexible and therefor more resistant to a massive shove like a wave hitting it. And of course UV.

This is just my understanding, do your own homework. I personally went with 1/4" acrylic, but now wish I had gone 3/8" on the larger openings. May redo them at some point. I'm still comfortable with 1/4" on the small openings.

https://forums.sailboatowners.com/index.php?threads/plexiglass-window-thickness.182638/
 
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Dec 11, 2015
291
Hunter 25 Plymouth
Thanks everyone for your input. Does anyone have a suggestion of the best place to purchase polycarbonate or similar materials?
 

TomY

Alden Forum Moderator
Jun 22, 2004
2,758
Alden 38' Challenger yawl Rockport Harbor
Thanks everyone for your input. Does anyone have a suggestion of the best place to purchase polycarbonate or similar materials?
I buy polycarbonate at my local glass biz. I've bought 4X8' sheets of 1/4" and smaller pieces of thicker stock. The last time I needed some 1/2" thick polycarb. , they were able to find some cut offs to work. It saved me about 1/2 $.

I needed it for dorade box tops.

Dorade boxes close (1 of 1).jpg
 
Jun 8, 2004
10,024
-na -NA Anywhere USA
It would help to know the year either the original or the later one in the 2000 model years. Is there a local boat repair yard near you to see if they have any scrap material that they will sell cheap to you. Try the forum store as well.

If you do try to cut out a window go at a slow speed using very fine teeth and please do not use acetone as it will craze the material
 

dLj

.
Mar 23, 2017
3,373
Belliure 41 Sailing back to the Chesapeake
I have to say, polycarbonate vs acrylic is another one of those subjects like what's the best anchor that can lead to long drawn out pro's and con's with discussions of differences in thermal expansion and contraction to whatever level you want to go.

I've had both on my boats at different times. Had one boat with both at the same time. They are both excellent. The only caveat I will reiterate is if you go with polycarbonate, get the UV resistant types. If you can't get it, go with cast acrylic.

dj
 
Feb 18, 2019
1
Hunter 33 Monument Beach
Check J. Freeman in Dorchester Ma. I've got product from them before. Very knowledgable, huge selections and options and will even make some cuts for you. They aren't too far from Plymouth.
Best of luck!
Ron
 
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