I remember testing half a dozen adhesives suggested by expert marine store salespersons. The labels all said they could be used with "plastic" but all also warned to test first, which I did. I have broken too many mountain bike helmets to tell you for sure that I gave the 3M5200 a fair test, but I think I did.

Yes, plastic was roughed up with #60 and scored with a knife as well.

Since there is some amount of grip and the cutout to lid joint is cosmetic and not structural it might be fine, I would not trust it to glue the lip to deck joint which affects the watertight integrity.

I cannot remember where it was but I was reading an article on a website about how this (profesional) guy patches HDPP boats with fiberglass and epoxy. He said the secret was hitting the plastic with a blow torch just enough to temporarilly change the plastic's molecular structure so the epoxy would adhere. He said he heated the plastic to just before it would begin to discolor. He then had a short amount of time to get the first layer of the patch on.

As a side note, in my current indenture I work a bit with polypropelene and injection molding machines and this stuff does not even adhere to itself well, even at 600 degrees and under pressure. Parts, when they break, always break at seams.

Not even the 5200? plastic roughed up well?

: I had planned to use a screw-in Beckson for a day hatch, and wanted to glue
: the cutout "cover" to the lid with 5200.

: Shawn