3M makes a great product. I have used it in aviation on floats and windshield. You can get it in black or white I have seen it at most marinas and home depot. put it on and smooth out with a latex glove on as it is difficult to get off. It is a great adhesive also.
3M 5200
Permatex Black Plastic Welder #84145 Use it a lot. I get it from my NAPA store. Stitch things together so there straight. Then fill in the voids after. Sets up in 5 minutes. Great stuff !! Use Krylon plastic paint after.