Together with her sistership , the destroyer tender was designed to provide service, supplies, and repairs for three divisions of destroyers for a two-month period under wartime conditions. Her facilities included storage for fuel and lubricating oil, fresh water, provisions, spare parts, and repair facilities such as optical and machine shops. Following her shakedown and trials, Whitney, initially based at Boston, Massachusetts, tended destroyers of the Atlantic Fleet and soon thereafter commenced a routine of following the fleet south for the winter, operating out of such ports as Gonaives, Haiti, and Guantanamo Bay, Cuba. She first visited the
Panama Canal Zone in February 1926 and returned to
Hampton Roads in the spring. During the more temperate months of the year, Whitney operated from ports along the eastern seaboard of the United States. She followed a steady routine of summer and winter fleet movements until February 1932, when she transited the Panama Canal for the first time, en route to the California ports of San Diego and San Francisco. After operating on the Pacific coast for the next two years, Whitney returned to the Caribbean in April 1934 and to Hampton Roads that June. However, her stay in the Atlantic was a brief one, for she was back on the Pacific coast that autumn, reflecting growing American concern about the naval challenge to the United States in the Pacific resulting from the expansionist aspirations of Japan. After repairs at
Mare Island Naval Shipyard in December 1934, Whitney visited
Port Angeles, Washington, in May 1935, supporting destroyers taking part in
Fleet Problem XVI, the fleet maneuvers conducted that year in the northern Pacific from the coast of Alaska to the vicinity of Hawaii. During
Fleet Problem XVI, Whitney also visited Dutch Harbor, Alaska, and made her first voyage to Pearl Harbor, Oahu. Back at San Diego in June, Whitney remained on the west coast for a year before heading for the east coast in June 1936, following Fleet Problem XVII. She subsequently tended the Battle Fleet's destroyers at Balboa, Canal Zone, in the autumn and returned to San Diego in November 1936. With Fleet Problem XVIII during the spring of 1937, Whitney joined the fleet train in voyaging directly to Pearl Harbor in April. She remained in Hawaiian waters only a month, though, before she returned to San Diego following the Battle Force vs. augmented Scouting Force exercises. The destroyer tender followed the same routine the following year, visiting Pearl Harbor in May 1938, as part of
Fleet Problem XIX. Whitney transited the Panama Canal again in January 1939 and operated briefly out of
Bahía Limón, Canal Zone. After participating in
Fleet Problem XX, Whitney returned through the canal to the west coast, reaching San Diego in May. Following the movement of the fleet to Hawaii that had begun upon conclusion of
Fleet Problem XXI in April 1940, Whitney made another trip there in the autumn of that year. The destroyer tender performed her vital but unglamorous duties at Pearl Harbor into the summer of 1941. She departed Hawaiian waters on 20 August, proceeded to the west coast, and touched at San Diego and Long Beach before returning to Oahu on 18 September. == Pearl Harbor attack==