CGS Margaret was the first vessel to be built specifically for the Canadian Customs Preventive Service. Delivered in 1914, she was transferred to the Royal Canadian Navy and served as HMCS Margaret during the First World War. Following the war, Margaret was returned to the Customs Preventive Service spending most of the 1920s intercepting smugglers during American Prohibition. In 1932 the ship was transferred to the Royal Canadian Mounted Police. The ship was sold shortly thereafter, and was subsequently acquired by the Brazilian Navy and renamed Rio Branco, utilized as a hydrographic survey vessel. Rio Branco was discarded in 1958.