The best thing I have found to restore the original sheen to the hull is the 
McGuire's three step process which is available thru WM. The first step 
removes the oxidation. The second step buffs it out and the third step restores the 
waxes that have been previously removed. Don't skip any of the steps. I used a 
1/2" drill and a wool buff pad. A little trial and error will show you the 
best method with the drill. It really will return the hull to the original 
condition without damaging the gel coat. Mine has been on for a year and only will 
require another coat of wax to bring it around this time.

Rummy