We used something called Sail Wash, purchased from Wash-Safe.com.
(It's a mylar layered jib)
We put it in our hot tub and ran the jets on high for 12 hours.
The sail came out a lot cleaner and the
water was bright green when we got done.
We laid out the sail on the driveway and rinsed it really good.
It's a lot better, but still has some mildew between the layers.
If I had it to do again, I'd probably use some
laundry soap and Oxalic acid.