First. Kudos for attempting the job. It actually is a good job, so don't fret. As others have said, it's virtually impossible to make the gelcoat match without super human effort that IMO isn't worth it. Gelcoat repair
was my job at a couple of marinas so I know your problem. A couple of tips:
1. Stop trying for a perfect repair
, it won't happen.
2. It's not a structural repair
so IMO there is no need for beveling the repair
. That slope makes the underlying color bleed through your thin repair, as you've seen
3. I like rough holes with vertical sides. Much easier to sand flush and the repair won't pop out. Honest.
4. I use making tape instead of plastic. You can get a more fair result because the tape is stiffer and won't wrinkle. You're sanding it anyway, so the smoothness that the plastic imparts is lost when you start sanding.
. Yup. If you absolutely insist on a color match, a thin dab of paint
feathered into the surrounding gelcoat works. BUT it must be an exterior paint
. I really don't recommend this action because you can make a passable job a mess in a hurry. But we did it with IMRON and it worked. I've done it a few times since, but it's just not worth the effort.