In the 15 years before I bought her, Red Wing had covered more miles and cruising grounds than most boats twice her size. She had been hard used, and it showed in a few places like this.
Looking down from the deck, it appears that about 2" of fiberglass was structurally damaged. Around the structurally damaged section, the fiberglass flexed under the impact, creating spider cracks in the gelcoat. The spider cracks radiate out 9" to either side of the impact area, but the fiberglass is sound.
The "quick and dirty" way to fix it would be to just slop some sealant on the cracks to prevent leaking, but that wouldn't be as strong as it was new. To do a proper repair, I need to grind out the damaged glass and replace it. If we ever took a hit like that again, I'd want her just as strong as before.