The outer surface of a fiberglass boat is normally a special resin called gelcoat. Gelcoat has little structural value-the underlying laminates of resin-saturated glass fabric provide that-but gelcoat protects the hull and gives it its color and shine.
Time and exposure eventually erode the relatively soft surface of gelcoat, leaving it dull and chalky. Fortunately, the gloss usually can be restored.
The first step in restoring the gloss to dull gelcoat is always a thorough cleaning.
For dependable results from wax or polish, the gelcoat surface must be completely free of oil and grease. Detergents often fail to fully remove these contaminants from porous gelcoat.
Keeping gelcoat coated with wax-starting when the boat is new-is the best way to prolong its life. Regularly waxed gelcoat can retain its gloss for 15 years or more. The real purpose of a coat of wax is to protect, but wax also has restorative properties if the gelcoat is not too badly weathered.
Polish is not a coating, but rather an abrasive-like extremely fine sandpaper. Polishing removes the pitted surface rather than coating it.
After polishing, you should apply a coat of wax to protect the surface and improve the gloss. If the gelcoat is weathered so badly that polish fails to restore its shine, you will need the stronger abrasives rubbing compound contains. Wax on the surface can cause the compound to cut unevenly.