Shamrock was one of the series of legendary racing yachts, each of the same name, built for Sir Thomas Lipton, the tea magnate and one of the greatest yachtsmen of its golden age. Each Shamrock was an improvement upon her predecessor and Lipton mounted five unsuccessful America's Cup challenges with them between 1899 and his final attempt in 1930.
Westward was a large American schooner of 338 tons built in 1910 and sold at the Kaiser's instigation to a syndicate of German merchants who renamed her Hamburg. In a brilliant start to her career she won all eleven races in which she competed, her most notable as well as frequent victim being Lipton's Shamrock. After the Great War, she was sold to the American Clarence Hatry who restored her original name and whose success with her in the 1920 season almost equalled that of ten years earlier. Sold again in 1924, she continued racing until the mid-thirties when she disappeared from international competition.