Our SeaRaider has a plywood centreboard, the heel (leading edge low tip) often got damaged through hitting stones and gravel. The same happened to the rudderblade heel. The damaged areas were always very small, just the lowest 1- 2 inches were ever affected.
First I just sanded and re-painted, but that repair only lasted until the next bang.
I finally epoxied on a few layers of glass over the heel, and that repair so far survived a few groundings without major damage. But the contour of the heel makes it diffcult to apply the glass without wrinkles, so it's not a very neat job.
Our BayRaider has a GRP board and rudderblade. Because I anticipated that there would be similar problems to the heels from hard groundings, I put on brass protectors. The little notch in the board heel had to go in the the process, but I think that it would not have lasted long anyway.