(SS-38: dp. 392 (surf.), 521 (subm.); l.153'7"; b. 16'8"; dr. 13'1"; s. 14 k. (surf.), 10.5 k. (subm.); cpl. 28; a. 4 18" tt.; cl. K-3)
K-7 (SS-38) was launched 20 June 1914 by the Union Iron Works, San Francisco, Calif., under a subcontract from Electric Boat Co., Groton, Conn.; sponsored by Mrs. Katie-Bel McGregor, daughter of the President of Union Iron Works; and commissioned at Mare Island 1 December, Lt. J. V. Ogan in command.
As a unit of the Pacific Torpedo Flotilla, K-7 sailed for San Diego 26 December, arriving the 28th to commence shakedown and training along the California coast. She returned to San Francisco 4 June 1915, then departed 3 October for experimental duty in the Hawaiian Islands. Arriving Pearl Harbor 14 October, she conducted torpedo and diving tests and participated in operations developing the tactics of submarine warfare. K-7 departed Pearl Harbor 31 October 1917, and sailed via the West Coast and the Panama Canal for antisubmarine patrol duty in the Gulf of Mexico.
Arriving Key West, Fla., 8 January 1918, K-7 patrolled the shipping lanes of the Gulf of Mexico from the Florida Keys to Galveston Bay. She returned to Key West from Galveston, Tex., 27 November and resumed training and development operations until departing for Philadelphia Navy Yard 14 April 1919. She received an overhaul from 21 April to 10 November, then resumed operations out of Key West in the Caribbean. Following additional overhaul during the latter half of 1921, K-7 resumed her training and development operations at the Naval Academy 19 January 1921. For more than 2 years she ranged the eastern seaboard from Hampton Roads, Va., to Provincetown, Mass., training submariners, conducting diving experiments, and practicing underwater warfare tactics. During April and May 1921 she visited the service academies at Annapolis and West Point. After conducting almost 7 months of submarine instructions at New London, Conn., she arrived Hampton Roads, 7 September 1922, for submarine flotilla operations in Chesapeake Bay. Subsequently, K-7 decommissioned at Hampton Roads 12 February 1923. She was towed to Philadelphia 23 August 1924; struck from the Navy List 18 December 1930; and sold for scrap 3 June 1931.