A few years ago, I scraped my bottom down to gel coat, rolled on 6 coats of Interprotect 2000e, and a couple coats of WM ablative bottom paint. I am not happy with the ablative, and have decided to go back to VC17. I am sanding the bottom with a 5" random orbital sander and vacuum, and have no problem removing the bottom paint, but when I hit the Interprotect with it's slightly orange peel surface, my discs dull almost immediately. I would like to get the Interprotect smooth, and eliminate all the ablative that is in the orange peel crevices. I am using 60 grit discs, which seems to be a good grit, but they just dull too fast. Any suggestions as to what type of abrasive I need that will stand up to the epoxy for a longer time? I know there are 4 1/2" grinder options, but I would prefer to be able to stay with the random orbital sander - especially since I need to keep a vacuum attached. I am also not confident in my ability to keep a grinder from gouging the surface, where the flexible pad on the sander follow the hull contour well. I do have access to a 6" random orbital as well.