O-Class legacy: a dive into the general characteristics and service history of the U.S. Navy’s versatile submarine fleet

The O-class submarines of the U.S. Navy were divided into two classes by Electric Boat and Lake Torpedo Boat Company, as a result of the lessons learned from World War I. They were essential to naval operations even in the face of difficulties.

In direct response to the lessons gained from the previous L class, the United States Navy developed a class of sixteen submarines known as the O-class. The 1918 commissioning of these submarines, which were around 80 tonnes heavier than their predecessors and built with more power and endurance to conduct prolonged ocean patrols, was a major advancement. America’s entry into World War I spurred the O class’s rapid construction, which resulted in a faster production process than earlier submarine classes.

The O-class submarines were divided into two groups: group 1 consisted of O-1 through O-10, which were designed by Electric Boat, and group 2 consisted of O-11 through O-16, which were designed by the Lake Torpedo Boat Company. The latter is occasionally regarded as a separate class. Despite their premature entry into service, the group 2 submarines participated in naval operations before the end of World War I. Remarkably, eight of the group 1 boats from Electric Boat were recommissioned as training vessels in 1941 and went on to serve in World War II.

Five shipyards shared the task of building the O-class submarines. Built-in Kittery, Maine’s Portsmouth Navy Yard, Bremerton, Washington’s Puget Sound Navy Yard, and Quincy, Massachusetts’s Fore River Shipyard produced O-1, O-2, and O-10. However, the Lake Torpedo Boat Company in Bridgeport, Connecticut manufactured O-11 through O-13, and California Shipbuilding (previously Craig Shipbuilding) in Long Beach, California built O-14 through O-16. The prompt completion and deployment of the O-class submarines during a pivotal period in naval history was made possible by the cooperative efforts of various shipyards.

General Characteristics:

A class of submarines built for the U.S. Navy was known as the O-class United States submarines. Different specifications were used for the construction of the two groups of O-class submarines. In terms of displacement, Group 2 had a somewhat lower displacement of 491 long tonnes (499 t) surfaced and 565 long tonnes (574 t) submerged, compared to Group 1’s weight of 520.6 long tonnes (529 t) when surfaced and 625 long tonnes (635 t) when submerged.

The two groups’ O-class submarines were different in size. The Group 1 submarines were equipped with 2 × 440 hp (328 kW) NELSECO diesel engines and measured 173 ft 4 in (52.83 m) in length and 18 ft (5.5 m) in beam. Conversely, the Group 2 submarines measured 175 feet (53 metres) in length and 16 feet 7 inches (5.05 metres) in beam. They were powered by two Busch-Sulzer diesel engines, each producing 500 horsepower (373 kW).

Additionally, the O-class submarines’ propulsion systems varied between the two groups. Group 1 submarines had electric motors with a displacement of 2 370 hp (276 kW) from the New York Navy Yard (O1–O5) or Electro Dynamic Co., whereas Group 2 submarines had a displacement of 2 400 hp (298 kW) from Diehl Manufacture Co. There were two × shafts and two × 60-cell batteries in each group.

When surfaced, both classes of O-class submarines were capable of reaching 14 knots (26 km/h; 16 mph). Submarines from Group 1 were able to attain 10 knots (19 km/h; 12 mph) whereas those from Group 2 were able to reach 11 knots (20 km/h; 13 mph). When surfaced, the submarines could cover a distance of 5,500 nautical miles (10,200 km) at 11.5 knots (21.3 km/h; 13.2 mph) and 250 nautical miles (460 km) at 5 knots (9.3 km/h; 5.8 mph) while submerged.

The O-class submarines had a test depth of 200 feet (61 metres), and each one could have a complement of 29 crew members. Equipped with a retractable deck gun and four × 18-inch (450 mm) torpedo tubes that could fire eight torpedoes, the vessel was equipped with an armament of one × 3-inch (76 mm)/23 calibre.

Service History:

The history of the US O-class submarines’ operations was varied. O-1 through O-10 were part of the first group, which mostly operated in the anti-submarine mission off the US East Coast. On July 24, 1918, a British merchantman opened fire on two of the boats, O-4 and O-6, resulting in a noteworthy event. O-4 took six hits on its conning tower and pressure hull, resulting in minor damage. In November 1918, the O-3 to O-10 boats were also part of a submarine force deployed to the Azores; however, they were brought back once the Armistice was signed.

The second set of O-class vessels, O-11 through O-16, encountered difficulties, mostly related to electrical issues. O-13 was involved in an unfortunate mishap that caused the patrol boat Mary Alice to sink, while O-11 spent five months at the Philadelphia Navy Yard for an overhaul. Under the stipulations of the London Naval Treaty, all six Group 2 boats were decommissioned in July 1924 notwithstanding refits and overhauls. Notably, in November 1931, O-12 was abandoned in a Norwegian fjord after being disarmed, renamed Nautilus, and used in an Arctic expedition by Sir Hubert Wilkins.

The first batch of O-class submarines operated successfully, with the loss of three crew members when O-5 was rammed and sunk by a cargo ship in October 1923 close to the Panama Canal. The remaining Group 1 boats were retired in 1931 but were recommissioned in 1941 as training boats at the Naval Submarine Base New London, Connecticut, except O-1. Thirty-three crew members perished when O-9, one of them, fell during deep submergence tests in June 1941.

The O-class submarines were modified in the interwar period to improve their safety in the case of sinking. To identify the submarine’s location if it became trapped on the bottom, marker buoys were installed fore and aft. Additionally, a motor room opening was added, and a step was created by tapering the after casing. The seven surviving O boats were used as training platforms for the Submarine School at the New London Submarine Base during World War II. After a remarkable 27-year service, the last O-class submarine, USS O-4, was decommissioned in September 1945, making it the longest-serving submarine in U.S. Navy history.