I had an older boat with stained hulls and used Soft Scrub with really good success. Comet is pretty abraisive and can leave nasty scratches. Soft Scrub has very mild abraisve backed up with bleach. For particularly tough areas I used a random-orbit sander with soft scrub and went very, VERY easy on the pressure. Once everything was clean and well rinsed I applied a fiberglass sealer then a wax. The result was pretty good considering the boat was 10 years old and had traveled a lot of road and water miles. The one precausion is to go easy on repaired areas or anyplace the gelcoat might be thin. Abraisive cleaners, even mild ones, take off a microscopic layer of material each time you use them and can remove a thin layer of gelcoat over time. Also, wear something you don't mind getting bleach on. Your favorite regatta T-shirt could get wrecked in this cleaning process.



H-20 #896