Michael Bushey wrote:
My 15 year old boat has black patches on the indoor outdoor carpet. It
appears to be old mildew. Vinegar and baking soda didn't touch it. Carpet
cleaner doesn't work. Any suggestions appreciated.


On a boat it is probably polypropylene and probably safe to bleach.
Blasting it with a hard stream of water will get a lot of it out, but
bleach is the only thing I know that will kill mildew.