I have a boat that I recently baught it's a 2000 four winns with an open bow good boat but it was stored without a cover and was stored under a tree after cleaning with basic soap and water there is still a brownish stain on the top surfaces of most of the white vinyl interior. It seems to come off somewhat with some serious scrubbing. I am wondering if anyone has a suggestion for some heavy duty vinyl cleaner and any kind of method of cleaning white vinyl without damaging and any percautions on what type of cleaning agents NOT to use????