Last Fall I used a product called Zing(boat hull cleaner), amazing stuff and pretty simple to use, wipe on and wash off and it is spotless Follow the directions/recomendations(it should be diluted) but here’s a couple warnings they didn’t mention or I didn’t see. This stuff dis-colors Chrome and Rubber, the chrome simply turns black and the rubber white. In my situation the chrome was the Tongue Jack where this stuff dipped and the rubber was the outlets for the livewell on the side of the boat. You should be able to find this stuff or something similar at your local boat dealer or Fleet farm.
I hope that helps
Willnot
Willnot = no matter what I do that knot will not come out