When I called up the company that makes the Jim Black hatches used by General boats, they said that the outer flange was impossible to repair. I tried 5200 long dry (the devil's glue) and it worked! Goop was used to secure the gasket. A piece of 1/4" 16.75x16.75 white translucent plexiglass was glued to the flange with West epoxy G-10 and voila a like new hatch.

Best Regards
Jeff Smith
www.http://JeffSmithPhoto.Net
732-236-1368