What is 954 feet long, carries 2,200 passengers, plus two ballroom dance teachers from Smith Valley? The Carnival Cruise ship, Spirit. "Would you be available to give ballroom dance classes on a cruise to Hawaii?" the telephone voice inquires. Available? "Absolutely," would be a better word.On the five-day passage to Hawaii, our job is to give a dance class each morning and afternoon. Once in Hawaii, the ship makes calls on the four major islands, and we become regular passengers. To add to the sweetness of our good fortune, our stateroom and all meals are cost free.Life aboard a ship …