Design of a harbor defense submarine began in May 1914 with a submerged displacement of 400 tons and good submerged speed and endurance; no deck gun was necessary, surfaced endurance would be 2500 miles at 11 knots, 12 days of supplies were needed. Test depth requirement was 200 feet. Seven "N" boats were approved on 29 October 1914; their keels were laid March to July 1915 at Seattle Drydock & Construction and Lake Torpedo Boat Co. and were commissioned 1917-18.
Early submarine classes such as E, H, K, L, M, N, O, and R, known as "pig boats" or "boats" because of their unusual hull shape and foul living conditions, ranged in displacement from 287 to 510 tons. The fastest "boats" achieved top surface speeds of 14 knots under diesel power. During World War I, US submarines were divided into two groups according to mission. Boats of the N and O classes, as well as some of the E type, patrolled American coasts and harbors in a defensive role. Some K, L, O, and E class boats conducted offensive, open-sea operations from the Azores and Bantry Bay in Ireland. They supported the Allied effort to maintain open sea lanes along the European coast and in the approaches to the British Isles.
Used for coastal patrol duties during World War One, they filled training roles after the war. The Lake built boats (N-4 thru 7) were decommissioned in 1922 and scrapped. The Seattle built boats (N-1, N-2, and N-3) were decommissioned in April 1926 and scrapped in accordance with the London Naval Treaty in 1930-31.
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