If someone with a Roman numeral in his name asks you to go sailing with several dozen of his closest friends on his yacht, chances are good that the boat is a powerboat, not a sailboat, and you should wear a blue blazer. Other than that, you're rarely expected to wear the traditional blue blazer on the water. These days, the only times you're truly likely to see blazers or cocktail party attire on the water are for a wedding, a boat christening, or some other really formal party. Some top sailors don't even own a blue blazer, anymore.

But before you head off to lunch at the New York Yacht Club (which, by the way, is in midtown Manhattan, not on the water), throw on a coat and tie.

Even at formal parties on large yachts, wear soft-soled shoes and leave the spike heels at home. If someone invites you to go sailing on a fancy yacht, especially an antique wooden boat, be forewarned that you may be asked to take off your shoes to prevent damage to the wooden decks. So make sure that you have trimmed your toenails and that your socks are presentable.