Mostly on the hull but also in general, most boats are covered with them. I've tried multiple pad/compound combinations to using different RPMs and pressure etc... Is the only way to wet sand or machine sand them. For wet sanding detailed instructions on grit,pressure,direction backing pad etc would be great. My boss wet sands (to remove oxidation)using 2000 grit but aways ends up being more work because he uses just his hand and it comes out all uneven with more scratches and finger marks. It's enough trouble to try to remove his mistakes and the scratches that where already there