It's time to add a stripe or other custom design to your boat and you don't want it to look like you were attacked by amateur graffiti artists. Like any painting project, preparation is the key and, in this case you will be painting over the slick, shiny surface of gelcoat. Not only do you want the paint job to look good, you want to preserve that shiny gelcoat-like surface. With a bit of work and a fair amount of care, you can achieve your goal.