DIY sail cleaning ....
If you dont have bare teak (decks or 'brightwork'), you can clean the sail ON the boat:This is for WOVEN WHITE DACRON ONLY ... not for laminated sails or colored dacron.Materials needed:Sodium Silicate detergent Oxalic acid (hardware store stuffGarden hosesoft bristle brush on long (5 ft.) handleplastic tarpOn a cloudy windless day -----Slowly raise sails as you spritz on sodium silicate plus a little water mist from the hose, lightly scrub as you raise. Do one side at a time. Then lower to deck and cover with plastic tarp. Let soak at least one hour. Object is to totallly saturate the sail material with detergent and water. Tarp prevent detergent mix from drying. Remove tarp, slowly raise as you scrub with soft brush, spritz with more detergent and water as needed dto keep sial wet. lower to deck and cover and let soak for another hour. Raise and scrub another time. Then drop to deck and raise again while 'blasting' with gardfen hose to remove all dissolved crud and detergent. Raise/sinse several times until NO soap bubbles are evident. This should dissolve all growth (mildew, air pollution, oil, etc.). By now there will onoly be 'shadows' of stains and dirt. Be SURE sail is well rinsed before proceding to the next step. Mix up a strong solution of oxalic acid and warm water, and apply as you did with detergent (apply oxalic with brush). Oxalic will bleach out all iron stains including tannin stains. Oxalic will almost immediately remove all the brown and rust, etc. Caution: wear gloves, foul weather gear, goggles as oxalic acid rapidly becomes absorbed through your skin and reforms as very sharp crystals in the nephrons of your kidneys. Thoroughly RINSE sail when fully bleached. Let hang to dry or go sailing. Should remove MOST of the dirt and debris, most 'fungus', most 'air pollution' and most tannin/iron stains.