Hey guys - we are always using some degree of surface prep prior to ceramic coating. This Pathfinder is a new boat, but even still, has swirl marks and micro-scratches from the factory. In most cases, even on a new boat or vehicle, a single step buff prior to coating is a good idea. As you guys know, we recommend using a Glossmeter for Professional detailers so that you have a number to shoot for. If the GU reading is less than 85, you should be doing some buffing. For DIY, most people don't have access to a glossmeter. You ultimately want to be happy with the surface before applying a coating. If you put a coating over top of imperfections, it will lock it in, making it harder to remove. In some cases it will make the scratch or oxidization stand out even more. That said, older boats with thin spots in the gelcoat, or older cars with single stage paint, you have to be careful and may require other steps beyond buffing. You guys are the Pros though, when do you use surface prep?