Well,...you could head to West Marine and pay 25% more for a "boating" product...or,...
Head to your local auto parts store and get some McGuire's Cleaner/Wax.
In one step you remove the oxidation that results in that chalky look and get a bit of wax protection.
If the oxidation is heavy, step up to McGuire's Rubbing Compound. Be careful using that with your power buffer though... you could "polish" right through your gel coat...and don't ask me how I learned that...
Whichever route you go, make sure to finish the job with a quality wax. You'll enjoy watching the water beading up on the hull of your ride, oxidation will be greatly reduced and you'll enjoy quicker clean-ups after using your boat as well!
Good luck and happy "WAX ON, WAX OFF-ing!!!"