It sounds like you may have old Lexan(polycarbonate) for the fixed ports.
Lexan is stronger (i.e. bullet proof) so often the lens thickness is less than what would be used for acrylic. Lexan is easier to work with and will flex better around curved cabin tops. It also does not chip or crack as easily as acrylic, but it is softer so it will scratch up easier. Basic Lexan also degrades from UV more so that acrylic, but recent manufactures are now adding UV stabilizers and scratch resistant coating to polycarbonate (for example: Bayer Makrolon polycarbonate). The price for polycarbonate has also dropped significantly in recent years. But acrylic still has better UV longevity. Most all acrylic these days purchased at local glass shops are manufactured with both UV stabilizers and absorbers(the later blocking the transmission of UV light). A quick search at McMaster-Carr shows many flavors of acrylic: Antistatic, Scratch-resistant, UV-Resistant, Strengthened UV-Resistant, and even Mirrored. Here is the link: http://www.mcmaster.com/#acrylic/=11kwa0t - Paul E. 1981 C&C 38 Landfall S/V Johanna Rose Carrabelle, FL http://svjohannarose.blogspot.com/ > On Mar 17, 2016, at 12:00 PM, cnc-list-requ...@cnc-list.com wrote: > > Message: 8 > Date: Thu, 17 Mar 2016 11:15:35 -0400 > From: cenel...@aol.com <mailto:cenel...@aol.com> > To: cnc-list@cnc-list.com <mailto:cnc-list@cnc-list.com> > Subject: Stus-List Windows again > Message-ID: <15385256a6c-79e9-5...@webprd-m70.mail.aol.com > <mailto:15385256a6c-79e9-5...@webprd-m70.mail.aol.com>> > Content-Type: text/plain; charset="utf-8" > > > I have begun the process of replacing the ~ 15 year old fixed windows on > Water Phantom. They have been leaking for awhile and are severely crazed--so > much as to be opaque. > > Interestingly, when they were replaced I also replaced all the Lewmar opening > ports and none of these ports show any crazing--the acrylic/lexan (not sure > which is used in Lewmar's stuff) looks like new. > > I'd like to avoid a repeat of this crazing on my new windows and wonder if > the list has some advice on the specific kind of acrylic or lexan to use for > the windows to minimize this in the future. > > I am going with 3/8" bronzed acrylic but wonder if there is a specific type > that is recommended since there appear to be several different grades of > acrylic with different inhibitors, etc. > > Thanks, > > Charlie Nelson > Water Phantom > C&C 36 XL/kcb >
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