Registered users don't see ads


Discussion in 'Ask All Sailors' started by Plymouth Sailor, Feb 13, 2019. Add this thread to a FAQ

  1. Plymouth Sailor

    Plymouth Sailor

    Joined Dec 11, 2015
    167 posts, 30 likes
    Hunter 25
    US Plymouth
    Does anyone know what the thickness of plexi-glass should be for port windows on a 25' boat?

  2. Will Gilmore

    Will Gilmore

    Joined Oct 19, 2017
    4,489 posts, 2,440 likes
    O'Day 19
    US 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)

  3. Charlie Jones s/v Tehani

    Charlie Jones s/v Tehani

    Joined Mar 1, 2012
    1,699 posts, 654 likes
    1961 Rhodes Meridian 25
    us 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

  4. dLj


    Joined Mar 23, 2017
    333 posts, 137 likes
    Hunter 30
    US Snug Harbor, Lake Champlain
    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.


    Will Gilmore likes this.
  5. Gene Neill

    Gene Neill

    Joined Sep 30, 2013
    2,735 posts, 1,304 likes
    C-22, Albin Vega
    US central 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.

    Will Gilmore likes this.
  6. Plymouth Sailor

    Plymouth Sailor

    Joined Dec 11, 2015
    167 posts, 30 likes
    Hunter 25
    US Plymouth
    Thanks everyone for your input. Does anyone have a suggestion of the best place to purchase polycarbonate or similar materials?

  7. TomY

    TomY Alden Forum Moderator

    Joined Jun 22, 2004
    1,676 posts, 1,582 likes
    Alden 38' Challenger yawl
    US Rockport Harbor
    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

    Will Gilmore and jon hansen like this.
  8. Crazy Dave Condon

    Crazy Dave Condon

    Joined Jun 8, 2004
    7,204 posts, 768 likes
    -na -NA
    US 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

  9. Justin_NSA


    Joined Jul 7, 2004
    5,457 posts, 1,118 likes
    Hunter 30T
    US Cheney, KS

    Will Gilmore, Jackdaw and TomY like this.
  10. Joe Blizzard

    Joe Blizzard

    Joined Feb 5, 2009
    191 posts, 32 likes
    Gloucester 20
    US Kanawha River, Winfield, WV
    I bought some scrap pieces on eBay a few years ago to make my hatchboards.

  11. dLj


    Joined Mar 23, 2017
    333 posts, 137 likes
    Hunter 30
    US Snug Harbor, Lake Champlain
    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.


  12. Patience h33

    Patience h33

    Joined Feb 18, 2019
    1 posts, 0 likes
    Hunter 33
    Patience US 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!

    Last edited: Feb 18, 2019

NEW rigid hatch covers
Hatch protection like never before. Tough, secure, installs in seconds.
20% OFF innovative boat clips!
FixClip holds laundry, tools, anything to rails and life lines even in strong winds.
Flexible steel chafe pads
Innovative new product made of flexible, laser cut stainless steel. Must see!
Mainsail covers
Pre-patterned mainsail covers to fit your boat