Worked on fixing the scratch today. I didn't finish, but I'd say today was mostly a success, being that I should be good enough to get the boat on the water the rest of the weekend.
Here's the gouge before I started. I pulled the bow eye off for the repair.
I used a 1/2" sanding drum on a pencil grinder to knock down the jagged chipped areas.
I mixed up some polyester resin, chopped fibers, and glass bubbles, and filled the deep parts of the gouge.
I knocked it down with sand paper and made sure it was lower than the final surface, and blended the repair area into the surrounding area some.
I followed Scott Danforth's recommendation and taped off the black/white line with fine-line tape, then masking tape. I bought natural gelcoat and the US Composites sample pack of tints. I made some black gelcoat, thickened it with cabosil, then rolled and brushed it on.
I pulled the tape as it was kicking and got a pretty crisp line.
Next I tried mixing up some white gelcoat to match. I threw my first batch out because it was way off. I went with my 2nd batch, thickened it, and applied it.
After sanding with 150, 220, and 320, I'm calling it good for today. There are some low spots in both black and white I'm going to have to fill again, so I didn't keep progressing with sand paper grits. Also, my white is way off. I'm probably going to sand it down and try again in the next couple of weeks, as I want it to match. I put the bow eye back on (crawling up into the bow under the dash sucks!) and put 4200 around it to seal it. All-in-all, I'm pleased enough with how my first gelcoat repair went, but I need to figure out the color matching thing.