Vinyl Seat Cushion Cleaner?

[st68]

It looks to be a fungus of some sort bleeding through from behind as opposed to a stain on the outside. Just a theory from the looks of it. Good luck with it, may be try some good old direct sunlight.

That could be the case and makes sense when I read what you wrote. This the firs time in two years that I took the seat cushions home with me and the affected areas is the parts of the cushions that never see daylight because they are always tucked against the inside of the boat... I will try sunlight. Thanks!