Remember how shiny your boat’s gelcoat looked in the showroom? Chances are its luster has faded a bit, but it can be brought back before your next launch.
First give the boat a thorough rinsing from the top down. This will remove surface dirt and dust particles that would abrade the finish if you simply hit the surface with a soapy brush. After the initial rinsing, then it’s time to perform a thorough wash with a cleaning product approved for fiberglass gelcoats, such as West Marine’s WM Boat Soap or Star Brite’s Sea Safe Boat Wash. (Many household soaps and general cleaners may contain chemicals or abrasives that are too harsh for gelcoated surfaces.) Finish with another full rinse.
Now you can assess the true condition of the finish. Gelcoat shines because it’s a smooth surface that reflects light. Even microscopic irregularities can diminish that shine, but those same irregularities may be restored with just a sealing compound, or a very mild polish such as Star Brite’s Premium Marine Polish with PTEF. Pick an area to test. If two or three passes with the polish don’t yield the desired results, move to a mild abrasive polish like Meguiar’s Premium Cleaner/ Wax or Color Restorer. If oxidation is heavier, and cleaner doesn’t do the trick, only then should you consider a cutting compound. Again, start with a less aggressive formula like 3M’s Marine Rubbing Compound, and move to a more aggressive compound such as 3M’s Marine Super Duty Rubbing Compound only as a last resort.
Tip: Single out areas that need additional attention, possibly circling them with a grease pencil. This allows you to use a milder polish on the remainder of the boat then carefully perform more aggressive refinishing on select areas.