Plexiglas window

[Palarran]

I have a very large 10' long plexiglas window on Palarran that due to flexing has come loose at the bottom edge. There is about a 3/4" gap for about 4' between the plexi and the fiberglass. The top, leading, and tailing edges are still affixed and seem to be in place. The window had kind of bowed out at the bottom creating the gap.

I've been kicking around ideas to repair this. One of them had been to remove the window completely and re-bed it. I guess they use a product similar to the stuff on auto windows to affix them back now. But, that seems risky due to the potential of it breaking while trying to remove it.

Another idea had been to drill a 1/2" round hole in the plexi, take a thick grommet and insert it, then go through the center of this and through-bolt it, using large fender washers on both sides, to the fiberglas. Over time I would tighten the bolt and pull the plexi back into place. I like this idea from the standpoint that it will also secure the window in place better. But it also risks breaking the glass.

My final idea is to just fill the crack with some type of flexible chalk. This would be easy to do and I could dress up the inside with a trim board so there wouldn't be a gap anymore.

A final note is that the plexi is not available from the factory anymore. So if it breaks, I'll have to probably have two custom made pieces as a new one won't match the opposite side. I don't want to imagine how much that would cost. The gap is at the curve of the window, not on a straight part.

Anybody have some advice?

[rebel heart]

I cracked the glass in one of my butterfly hatches (about 4'x2') and have one using plexiglass and another that uses the original safety glass. I just went to home depot and got some plexiglass, cut it to shape, and dropped it in. Wasn't too bad. In hindsight there are better types of plastic that resist "yellowing" better than others, and you want to make sure you don't crack the plexiglass when you screw it down.

Honestly I'd go with your "add more caulking" solution at least for the time being, or you just want to tackle the project for the hell of it. Maybe do the research now on where you'd get the replacement piece and what type you'd pick. If you source out some stuff online you'll probably have better results than just grabbing whatever home depot has laying around.

[Cotemar]

The adhesive FP uses is standard automotive window glass adhesive with one difference.
The windows are not glass, so a primer has to be used on just the window so the adhesive will bond.

Note:the outside of the plastic sheets are painted black for 2” around the periphery of the window so the UV light from the sun will not break down the adhesive.

On a car the adhesive is covered by metal or plastic trim, so the adhesive will not break down, but on our boat the edges are exposed to the suns UV light which is not good.

FP window info.

1) ACRYLITE GP acrylic sheet is a cell-cast acrylic sheet 3/8 thickness

2) Dow Automotive BETAMATE7120 Single-component, high-viscosity, atmospheric humidity-curing polyurethane bonding/sealing compound for high-strength, permanently elastic adhesive joints. Apply ½ thick and squeezed out to 3/8 when window is installed

3) Dow Automotive Betaprime 5404 Pinchweld and encapsulation Primer. Used only on the plastic window sheet. Lightly scotbright 2” around bounding edge and apply this primer onto the sanded 2” area around the outer edge

Mark