Here are some tips to restore fiberglass.
First of all, if the gel coat is cracked or deeply gouged, it will need to be repaired, refaired and then repainted with a two-part polyurethane.
However, if it hasn't gone that far and isn't damaged, but just needs that shine back, here's what I would try.
1. Buy or borrow a good 10" random orbital waxer / polisher with about 3 extra bonnet kits. DO NOT, I repeat, DO NOT use an electric drill.
2. Get half a dozen terry cloth rags to use as applicators.
3. Get some good Rubbing Compound.
4. After a thorough rub out with the rubbing compound, follow up with Finesse-It, Paste Compound. Take your time and do the best you can.
5. Next, apply a coat of Perfect-It Glaze. WARNING: Don't assume you know exactly how to do this job. Read and follow the directions.
By the way, before you start this project you should wash the entire hull, removing as much dirt, grime and sea critters as possible.