How to Clean Exteriors
If your unit has an aluminum skin, it can be cleaned with a mild detergent and water. You can use a marine grade wax or polish as well.
If it is made of fiberglass, use a mild detergent and warm water to clean the exterior with a soft brush or rag. For tough stains, a special cleaner may be needed (ask your dealer, marine supplier, or auto parts store). You can polish it with a marine-grade wax to restore the gloss and color. Any plastic can also be maintained with a general wash and polish.
Avoid citrus-based cleaners, and try to avoid using polish or wax on any decals.