Best to leave em alone. If you cant live with them sand them out with 220 grit wet sandpaper then 400 grit then 1000 grit and buff with rubbing compound and a buffer. Ive done fiberglass for a living all my life and I would just leave em. If you cant see the laminate at the bottom of the scratches they are harmless. It looks good from the bank!!! :dance:
The bottom of the boat is only seen when the boat is on the trailer, by the fishies in the water or if you make a really bad mistake on the sticks. Pretty isn't a requirement for the bottom of the boat.
Now, if you can see fiberglass fibers exposed through the scratches or if you see cracking on the inside where the scratches are, repair is in order. Flip the boat over and grind the whole bottom. Get System3 epoxy and glass microspheres. Mix it up and fill in all the scratches. Then sand it smooth and lay a whole new coat of fiberglass over the bottom and up the sides a couple of inches. Once that's done, go back with the epoxy/microsphere mix and fair up the edges where the new fiberglass lays over the old so you can't make out the new edge. Sand again then paint or gelcoat.
So, you're out several hundred bucks and probably more than a few months of valuable fishing time. Do you really think those scratches need to be fixed?
Or you could commision an artist to paint a nice picture of a shapely hen steelhead delicately colored in seductive silver and pink, and maybe the big bucks will follow your boat around.
As far as the scratches, I've been told by some glass driftboat nuts that if you can see light passing through the hull, then you have a problem. If not, don't stress it. I would agree with these posts though, if you see fibers sticking out, you might want to patch it up. I like to chew a whole pack of watermelon Hubba Bubba and stick that in the hole. Works good on aluminum as well, and wood.
painting herring on the borrom of your boat might not be a good idea... Ever seen "Jaws" If you feel a few thumps row very fast to the take out!!! or pull over and start casting a chrome little cleo :grin: