Applying gelcoat to a fiberglass surface is not really necessary, as gelcoat is a fiberglass resin itself. Most people think that the best way to prepare a fiberglass boat for a gelcoat application is to have it done in a local car repair shop, where they handle similar coats everyday. You can add a gelcoat surface to your fiberglass boat if you wish to change its color, if you have damaged the outside of the boat somehow, or there are other reasons for replacing the fiberglass shell which the boat came with using a gelcoat resin. If you plan to do this, following a few simple tips can help you to prepare your fiberglass for the application of this coat.