Fitting windows is messy, time consuming and expensive. They can easily take a full day each to fit. So I have long looked for a simple, clean, quick and cheap way to fit them. I knew that many vehicles use tape to fit their windows - so why not do so on boats?

So I did some basic research and then contacted 3M, and this is what they replied:

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Thank you for contacting 3M, the innovation company.  Our VHB tapes are suitable for bonding plexiglass windows to a fiberglass boat.  A similar application bonding windows in motor homes is currently utilizing VHB tape.

The VHB 5952 family may be a good choice, but we prefer tape 5962,which is the same product except thicker (62 mils thick). The extra thickness helps fill any gaps between the plexiglass (perspex) and the fiberglass to help insure a tight seal, plus the thicker tape will expand and contract more.  The VHB tapes will expand lengthwise three times the thickness of the tape.

Another tape that is an option is VHB 4979F.  This product is also 62mils thick. The core of the tape is gray, but the top and bottom surfaces are black (you can only see the gray at the edges).

With both products, it would be best to use Adhesion Promoter 111. Plexiglass can have a variety of coatings, such as anti-glare,anti-fog, or scratch resistant.  Some coatings are a bit slick.  AP111 helps insure the tape bonds well.

If the window has square corners, a small dab of sealant may be needed right at the corner seam to help make it water-tight.  Our 4000UV sealant is an option.

Regards,

John Dritsas
Inside IATD Product Specialist
651-575-4270
This email address is being protected from spambots. You need JavaScript enabled to view it.
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So we ordered a roll of 5962 and a small can of 111. We fitted the windows inside a shed with air temperature about 10C (50F). Our Skoota 28 is plywood with glass/epoxy sheathing which was well sanded.

We were amazed how quick the windows were to fit. One line of tape, pressed down, lift up the window and push into place. Maximum 10 minutes a window and no mess! With conventional "goo" you spend more time than that just putting masking tape on to try to contain the excess.

The day before launch it was snowing, then midway through our summer cruise the cabin temperature reached 40C (that's hot!). So a big temperature variation, yet no leaks so far in the first 12 months.

So I would strongly recommend that those of you fitting big windows investigate these 3M products. The only reason I say "big windows" is that the rolls are long - even after fitting 6 big windows on our Skoota 28 we have half a roll left. And I do not think the rolls come in shorter lengths

So we are using what left to fit wood trim etc inside. It doesn't move! (but of course it is relying on the interior paint/wood bond as we are retro fitting the parts onto a painted surface)

You can see the windows HERE