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Sirzones · 01-09-2021, 03:58

I’m installing new acrylic windows on my 74 c$c 30
I’m upgrading from 1/8” to 1/4” acrylic and thinking of using automotive windshield urethane as a sealant instead of the white ouch in strip that the factory used to hold the window in
Has anyone tried this before?
Next time windows get replaced I will be changing complete assemblies to port hole style windows, so I’m not concerned about the urethane getting in the frames

Nicholson58 · 01-09-2021, 04:10

I see no reason the automotive window glue would not work. It is a single component moisture cure polyurethane. I’m pretty sure 3M 4000, 4200, 5200 are variations on the basic formula. Automotive uses a glass etch followed by a bonding layer that is also a UV barrier. For Lexan they might recommend a different system. Maybe there is a YouTube video that would help. I know others have had UV issues where the sun damaged the glue to Lexan bond.

BTW, butyl tape is often used for this depending on the structure needed. It’s not glue and never hardens.

**tkeithlu** · 01-09-2021, 04:31

As Nicholson58 mentions, butyl tape gets recommended frequently on the forum for this job. It's available in white if you prefer, tidy, easy to trim, and yes, stays elastic.

flee27 · 01-09-2021, 04:59

Do your windows have any type of mechanical fasteners? From pictures is doesn't look like it.

I replaced my windows about 6 months ago. They are not held in with any mechanical fasteners. I used 3M VHB tape to hold the window in and Dow 795 to fill in the gap/seal the windows in place. If you clean and prime(special primer) the surface before using the VHB tape it will not fail. I use VHB tape for applications in my line of work (not marine) and in many cases it is stronger than mechanical fasteners. Normally the substrate will fail before the VHB tape.

If you back paint your windows to create a clean edge the weakness is the bond between the paint and the lexan/acrylic.

Good luck with you new windows. Huge improvement and a worth while boat project.

Foster