Use a fine 1000-grit sandpaper to scuff the surface and making it dull. Use a coarser paper on areas of heavier damage. Corners of the section need careful attention. For final scuffing use a foam sanding block. This will help in flattening any of the rough edges around the chips. After scuffing with sandpaper fill in the chips with body putty and smooth the surface. If you feel indentation on the surface sand some more. Take immense care that you do not remove the actual paint of the Boat.
Here is a site on boat hull repair 101.hope you like it . Www.boatbuilding.net/article.pl?Sid=05/10/07/1343256