Plastic Port Light Replacement ... SNAFU

[catalanc]

Hi Guys,
I had a portlight broken during knockdown and am replacing it (Catalina 22 MKII). I removed the old one and all the "goo" from he gelcoat. I cut the blank from 1/2" plexiglass and beveled the inside edge just like the old one; fits just fine. I applied 3M VHB tape (3/4") and put the window in place but the top/front corner does not hold. Removed and replaced tape and window two times with the same result. I think that the cabin is curved and the tape is not sticky enough to hold it in place. I was thinking of heating up the plastic with a heating gun to hopefully bend it a bit to match the cabin curvature. Thoughts?
cec

 

[agprice22]

Was the old one screwed down?
Portlights are often screwed to hold them in place while the adhesive cures.
I would be very careful with a heat gun. Plexi boils easily. You will still need to hold it in place while it cools.
I have always wanted to try a lead weight bags and hot water.

 

[kloudie1]

Residue (invisible but imbedded into the fiberglass) from previous goo is probably a problem... the area on the boat and the area on the glass should be rubbed with isopropyl alcohol then the area sanded lightly with something like 200 grit or finer.. then rubbed with alcohol and clean rags again.. Is the tape pulling off the plexi or pulling from the boat? whichever one it is pulling from is the one that needs more cleaning.. The tape takes a day or so to come to full strength so a brace or clamp may have to be improvised to secure the glass for a day or so..

 

[catalanc]

Andrew, old one not screwed down. Interesting idea anout hot water.
Claude, sanded and cleaned fiberglass with acetone. Tape sticking to fiberglass fine but not to plexiglass. Perhaps a wipe of the plastic with alcohol a good idea. Not sure how to clamp the window, though.

Thanks, guys.

 

[rgranger]

..... Not sure how to clamp the window, though.

Thanks, guys.

You need to make a brace to wedge against the plexi while the glue cures. A few dry runs will get the process right. I’m thinking you could get a broom handle and a c-clamp. Loosely clamp the handle to a stanchion post nearest the port and then wedge it against the plexi with enough force to hold the plexi in place... then clamp the pole in place while the glue cures

 

[catalanc]

Well, I woke up at 4 am this morning and thought .... d'OH! I could have used a block of wood and tightly taped down with gorilla tape. The broom handle approach sounds good as well. Won't get back to the boat until this weekend, but will keep you posted.
Thanks.
cec

 

[kloudie1]

It is important to lightly sand the plexi where the tape will be touching.. before rubbing clean.. Just making sure there is no miscommunication.. your post says you did that for the fiberglass.. but doesn't say the plexi was done as well. Not picking at ya, just clarifying..

 

[rgranger]

Well, I woke up at 4 am this morning and thought .... d'OH! I could have used a block of wood and tightly taped down with gorilla tape. The broom handle approach sounds good as well. Won't get back to the boat until this weekend, but will keep you posted.
Thanks.
cec

View attachment 150999

It is all about leverage