With their 10-meter sloop Sirius the Ahmansons of Los Angeles have sailed themselves to an enviable reputation as yachtsmen. Besides the thrill of competing in the biggest West Coast races, the Ahmansons have collected the handsome array of trophies shown here. This season they added the Los Angeles Yacht Club Whitney Trophy (silver ewer at far left), an award given at the finish of seven ocean races along the coast of southern California, and for the third year running they won the 128-mile Newport-to-Ensenada, Mexico race. The 11-man winning crew for Skipper Ahmanson includes his wife Dottie as first mate, and two nephews, William and Robert Ahmanson. A native of Omaha, Neb., Howard Ahmanson is president of the nation's biggest home savings and loan association and an insurance executive. He started sailing in earnest in 1948 and acquired the Sirius, built in Norway by Anker Jensen Asker, in 1953.