Hose 'em off
I think there are some sail cleaning products on the market but I've heard the best thing to do is hose them off on a sunny day & let them dry thoroughly before taking them off. Using detergents, etc can remove the starches which keep the sails stiff so I'd be concerned about using any kind of soaps. The only way to remove mildew stains is bleach, a no-no as it's too damaging. But if you were desperate to have the cleanest sails possible, I suppose the stuff they sell at WM would *probably* work fine. LaDonna