During World War I, the U.S. Navy put seven coastal defence submarines into service, which together became known as the US N-class submarines. The boats were split into two separate groups, each built to somewhat different specifications by several companies. The first three, N-1, N-2, and N-3, were designed by Groton, Connecticut’s Electric Boat Company and built in Seattle, Washington, by the Seattle Construction and Drydock Company.
On the other hand, the Bridgeport, Connecticut-based Lake Torpedo Boat Company designed and constructed the N-4, N-5, N-6, and N-7 submarines that made up the second batch. Although the seven submarines are all classified as N-class, the boats built by Lake Torpedo Boat Company are occasionally regarded as belonging to a different class because of their distinctive design and place of manufacture.
The division in construction represents the cooperative endeavours of various enterprises to support the navy operations during wartime, with each contributing their specialised knowledge to the creation of these coastal defence submarines. The N-class submarines were built by the precise specifications provided by their separate design and build teams, which helped to augment the capabilities of the U.S. Navy in World War I.
The diesel-electric N-class submarines built by the United States were intended for use in naval operations. They included the N-1 through N-7 models. The submarines had a range of differences in their specifications.
When N-1 to N-3 submarines surfaced, they moved 348 long tonnes (354 t) and 414 long tonnes (421 t) underwater. On the other hand, N-4 to N-7 had a displacement of 415 long tonnes (422 t) when underwater and 340 long tonnes (345 t) when on the surface. The length of these submarines ranged from 147 feet 3 inches (44.88 metres) for N-1 to N-3 to 155 feet (47 metres) for N-4 to N-7. The draft varied correspondingly with the beam’s range of 15 ft 9 in (4.80 m) for N-1 to N-3 and 14 ft 6 in (4.42 m) for N-4 to N-7.
N-1 through N-3 were diesel-electric systems that drove two shafts with a power source from two sets of 60-cell batteries. The NELSECO Diesel engines had a combined output of 600 horsepower (450 kW), while the Electro Dynamic electric motors produced 300 horsepower (220 kW). In contrast, Diehl electric motors, Busch-Sulzer Diesel engines, and comparable battery arrangements were found in N-4 to N-7.
Operating speeds for the submarines were 11 knots (20 km/h; 13 mph) when submerged and 13 knots (24 km/h; 15 mph) when they were over the surface. Able to accommodate a crew complement of 25 officers and men for N-1 to N-3 and 29 officers and men for N-4 to N-7, these submarines had a test depth capacity of 200 feet (61 metres). Four eight-inch (450 mm) torpedo tubes with a capacity of eight torpedoes each were part of the armament.
After the United States entered World War I, the N-class submarines were put into service and were vital to the naval endeavours. The 1st Naval District was the primary operating base for these submarines, with occasional operations conducted out of New York City. They served as part of the maritime defence plan during the war, their main task being to patrol the coast of New England.
As a result of a reassignment in 1922, the Seattle boats of the N-class submarines were assigned to the Submarine School located in New London. A different destiny struck the Lake boats, also referred to as the N-4 class. The Lake boats came to an end in 1922 when they were all disassembled and scrapped. A significant change in naval capabilities was evident in 1921 when their engines were removed and used to re-equip certain L-class submarines.
The Seattle boats remained in operation until they were taken out of service in 1926. They were dismantled in 1931, just like the Lake boats. The choice to decommission these submarines was made by the restrictions imposed by the London Naval Treaty, a global accord designed to restrain the naval armaments race and stop the escalation of military hostilities. As international accords and geopolitical realities influenced the fate of these vessels during the interwar period, the N-class submarines’ destruction signalled the end of an era.