Can water get trough the crack inside the hull ?
As for repairing small gouges like that, just rough up the gouge with a dremel tool, clean with acetone, fill with gelcoat(just enough to fill it), cover with masking tape, once it cures remove the tape,if you notice that you didn't apply enough gelcoat, repeat that step. Sand with 120,220,400,600 grit and finish it with rubbing compound
Marc..