just wash 'em
Not sure about your specific material, but after reviewing the posts in archives, a washing machine worked for me. I have a '84 31' with the original woven gray, mauve and beige fabric. I took the covers off (mine were filthy when I bought the boat), soaked them for several hours in everything I could find and then ran them through 2 cycles. (Note: 2 or so covers per load, and Warning: they are a bear to get back on the foam.)I tried a small cover first to make sure there was no bleading, etc, but given the number of previous posts I had some comfort level and it seemed to work. I have to say this was the most successful improvement I have made to my Hunter. They look like brand new.Also, Fabrize is a terriffic product.