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
US Navy (USN) 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 smaller than the preceding
L-class boats, and would be the smallest boats built for the USN until 1952. The boats were constructed by two companies to different specifications; , , and , were designed by the
Electric Boat Company (EB), of
Groton, Connecticut, and sub-contracted for construction to the
Todd Dry Dock & Construction Company, in
Seattle, Washington, and , , , and , 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. The Electric Boat submarines, referred to as the
N-1-class, had a length of
overall, a
beam of , and a mean
draft of . They
displaced , on the surface, and , submerged. The
N-1-class had a crew of 2 officers and 23 enlisted men. They had a diving depth of . The Lake submarines, referred to as the
N-4-class, had a length of overall, a beam of , and a mean draft of . They displaced , on the surface, and , submerged. The
N-4-class had a crew of 3 officers and 26 enlisted men. They also had a diving depth of 200 ft. For surface running, the Electric Boat submarines were powered by two
NELSECO 240V8FS
diesel engines, each driving one
propeller shaft. When submerged each
propeller was driven by an
Electro Dynamic electric motor. The Lake boats had two
Busch-Sulzer 6M50 diesels, and two
Diehl electric motors. Regardless of designer, the N-class submarines could reach on the surface, and underwater. On the surface, the boats had a range of at 11 kn, and 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. These boats retained the individual muzzle (outer) torpedo tube doors of the preceding L and
M-classes. 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. ==Service==