Use an ammonia-based glass cleaner and a Scotch Brite pad to remove dirt, sunscreen, and wax. sweat, etc. Clean thoroughly and let it dry completely.
If the boat is new, it is necessary to repeat the process several times. New boats have wax residues on their surfaces used as a release agent from the production mold, and if not completely removed, it can hinder the adhesion of Cer-Deck.