The N-class boats were authorized under naval appropriations for Fiscal Year 1915. In order to be able to afford a fleet submarine in the same appropriations (eventually to become the AA-1 or T-class submarines), the Navy reduced the amount of money allocated to coastal submarines significantly. This forced them to order a more austere and smaller design. The N-class would be over 100 tons smaller than the preceding L-class boats, and would be the smallest boats built for the USN until 1952.[1]
The boats were constructed by two companies to different specifications; N-1, N-2, and N-3 were designed by the Electric Boat Company of Groton, Connecticut and sub-contracted for construction to the Todd Dry Dock & Construction Company of Seattle, Washington, and N-4, N-5, N-6, and N-7 were designed and built by the Lake Torpedo Boat Company of Bridgeport, Connecticut. The N-boats built by Lake differ considerably from their EB brethren, but are of a similar size and have the same military characteristics and therefore are considered the same class.[2]
The Electric Boat submarines had a length of 147feet overall, a beam of 15feet and a mean draft of 12feet. They displaced 347LT on the surface and 414LT submerged. The N-class submarines had a crew of 2 officers and 23 enlisted men. They had a diving depth of 200feet.[3]
The Lake submarines had a length of 155feet overall, a beam of 14feet and a mean draft of 12feet. They displaced 331LT on the surface and 385LT submerged. The N-class submarines had a crew of 3 officers and 26 enlisted men. They also had a diving depth of 200feet.[3]
For surface running, the Electric Boat submarines were powered by two 2400NaN0 diesel engines, each driving one propeller shaft. When submerged each propeller was driven by a 280hp electric motor. The Lake boats had 300bhp diesels and 150hp motors. Regardless of designer, the N-class submarines could reach 13kn on the surface and underwater.[3] On the surface, the boats had a range of 3500nmi at and 30nmi at submerged.
The boats were armed with four 18-inch (450 mm) torpedo tubes in the bow. They carried four reloads, for a total of eight torpedoes. They were the last submarines to be designed without a deck gun until 1946.[4]
This class was the first US Navy submarine class completed with metal bridge shields. These had been omitted from previous classes to increase underwater speed. The previous classes used piping-and-canvas temporary bridges for extended surface runs; these were found to be inadequate on North Atlantic patrols in World War I. All forward-deployed submarines were back-fitted with metal "chariot" bridge shields during the war. The coastal patrol nature of the small N-class submarines was emphasized by their lack of a deck gun.
The seven submarines of the N-class were:
| Ship name and Hull no. | Builder | Laid Down | Launched | Commissioned | Decommissioned | Fate |
|---|---|---|---|---|---|---|
| (SS-53) | Seattle Construction and Drydock Company | 26 July 1915 | 30 December 1916 | 26 September 1917 | 30 April 1926 | Scrapped 1931 |
| (SS-54) | 29 July 1915 | 16 January 1917 | 26 September 1917 | 30 April 1926 | Scrapped 1931 | |
| (SS-55) | 31 July 1915 | 21 February 1917 | 26 September 1917 | 30 April 1926 | Scrapped 1931 | |
| (SS-56) | Lake Torpedo Boat Company | 24 March 1915 | 27 November 1916 | 15 June 1918 | 22 April 1922 | Scrapped 1922 |
| (SS-57) | 10 April 1915 | 22 March 1917 | 13 June 1918 | 19 April 1922 | Scrapped 1922 | |
| (SS-58) | 15 April 1915 | 21 April 1917 | 9 July 1918 | 16 February 1922 | Scrapped 1922 | |
| (SS-59) | 20 April 1915 | 19 May 1917 | 15 June 1918 | 7 February 1922 | Scrapped 1922 | |
Commissioned after the American entry into World War I, they were assigned to the 1st Naval District, primarily operating from Naval Submarine Base New London with some boats operating out of New York City at times, all patrolling the New England coast.
Built during a time in which USN submarine strategy and tactics were rapidly changing, the N-class coastal patrol submarines proved to be too small to be really useful to a Navy that was finding itself on the world stage. The Lake boats in particular were disliked for poor habitability and reliability. They served only an average of 3.5 years while the EB design boats averaged 8.5 years of service.[5]
By 1922 the Seattle boats were assigned to the Submarine School, New London, while the Lake boats were all scrapped in that year, their engines having been removed in 1921 to re-equip some of the L class. The Seattle boats were decommissioned in 1926 and scrapped in 1931 to comply with the limits of the London Naval Treaty.