You can try a Good Wax, other wise be sure what ever you use won't hurt the finish or the Gel Coat.
Can you take a picture of the Hinges? Are they Piano Hinges? those you can find in any well stocked Hardware store. Go stainless you'll never have to replace them .
1982 Pace Arrow P30 454
KarKaddy SS, Toad: 2009 Genesis
Tim, Joe and Lilly too. Mpls Minn.