Kauffman was assigned to the destroyer USS "Hopkins" under Lieutenant Harold G. Bowen, stationed at Mare Island Navy Yard following a Boiler explosion. He was commissioned Ensign on 6 June 1910, after completing two years of service at sea then required by law. After a period of "Hopkins" repairs and service with the Reserve Fleet, he was appointed commanding officer of the "Hopkins" in November 1912. Kauffman was promoted to Lieutenant (junior grade) on 6 June 1913 and commanded his ship until January 1914, when he was relieved by new commanding officer more senior in rank and transferred to the capacity of ship's executive officer. He participated with the "Hopkins" in the naval operations in Mexican waters during Veracruz Expedition in summer 1914 and was detached in November that year.