Star Brite Hull Cleaner Gel Spray is the ideal solution for removing scum lines and tannic acid stains from boat hulls. The gel formula "sticks" where applied for maximum cling time and cleaning power. Completely covers stains to penetrate and dissolve them. Specifically formulated to remove the toughest stains, including rust, dried fish blood and leaf stains. Works on all fiberglass and painted surfaces. Not for use on anti-fouling bottom paints. * New Gel formula * Ideal for vertical surfaces * Does not contain harmful acids * safe and easy to use