Bath tub, Bleach, Simple Green
I just cleaned the most horrid mess I have ever seen on a set of sails. The jib was totally green, except teh thread, which was black. The mainsail was even worse. I soaked them over night in a full bath tub with a couple cups of bleach. Rotating them eveery hour or so, so I would not miss anything. The following day I laid out a worn out C-Scow sail on the ground, put the sails out and scrubbed them with a brush and simple green. Rinsed them off and hung them to dry. The result was very good.