Cruising on both the Pacific and Caribbean coasts of Mexico, Central America, and South America for the last eight years, we have a higher regard for the lowly cabbage. Available in many of the most remote and modest pueblos, it can survive for two or three weeks in the tropics without refrigeration, long after the refrigerated lettuces and other green vegetables have withered. But no praise of its practicality for cruising sailors (or even of its healthful benefits) is more compelling than its versatility. We eat cabbage cooked and raw, for lunches and for dinners. (We haven't hit upon the breakfast recipe yet.) Usually I make one of the plentiful variations of cabbage salad, many of which have been born of that mother of invention - necessity. Cabbage Waldorf Salad, its genesis inspired by an old standard from childhood, is one of our favorites. It's one over which our guests rave. If kept refrigerated, it's even better the second or third day.