Mrs. Loel Guinness spends most of her time in the sun on her husband's 130-foot yacht, the Calisto. In the summer they cruise the waters of the Mediterranean, and in the winter the Caribbean and the Florida coastline. As an international traveler, Mrs. Guinness is also an international fashion pacesetter, known especially for her taste in play clothes. She puts her particular stamp of approval on clothes which suit her dark, Latin beauty and her life in the sun and on the sea. This winter her favorite costume for sailing or poolside relaxing—as here in Palm Beach—is a trim, slim outfit of white sailcloth. She found it on Capri, and SI has seen the look of it from Jamaica to California this winter. Its taut slenderness differs significantly from the loose, top-heavy silhouette which has been popular in American play clothes. With a white costume, Mrs. Guinness wears white espadrilles embroidered with sea shells, from Lanvin at Cannes.