Treehugger
I am not sure. Also, best add some masking tape around the hull, so you don't scratch the paint elsewhere. As I commented before, I am assuming that you will add a gloss coat, else, probably not a good idea, sanding plain paint tend to look, bad.

Marc Schnitzler
Later i saw these Edges comes from the Hull Part, maybe the mark to cut the Hull for a waterline model.