Out of all the costs in running a boat, I was amazed really at how reasonable a sail laundry was... let the pros have a go would be my first thought, you might be surprised.
Dettox whatever it's called now?
Vanish solution left on to soak for a short while.
Vanish got the mildew spots off my curtains, which I was impressed with. I do know it's a mild bleach but shouldn't be enough to do harm.
Call yr sail maker to confirm they're happy though.
Incidentally my sail maker (or rather they guy who made my sails) does not like those washing machine sail launders. He says too much rolly polly and scrunching! /forums/images/graemlins/smile.gif