Industrial pollution
A few years back I purchased my C 27 on the Delaware River near Philadelphia. The hull had a sticky film of pollution all over it. Auto exhaust, factory emissions, jet planes, etc. Simple washing wouldn't remove it, so I resorted to my old standy-by: Meguiar's Cleaner Wax for fiberglass. A thorough application by hand with clean cotton towels removed the pollution film, and brightened up the fiberglass. I normally wax my topsides (not non-skid) once per year with the Meguiars, and it keeps the boat looking sharp. Once the wax has been applied, the boat is much easier to keep clean, as dirt washes off readily.Randy