United States O-class submarine

USS O-1, lead ship of her class in dry dock at Portsmouth Nary Yard in September 1918
Class overview
Name:	O class
Operators:	United States Navy
Preceded by:	N class
Succeeded by:	R class
Built:	1916-1918
In commission:	1918-1931, 1941-1946
Completed:	16
Lost:	2
Retired:	14
General characteristics
Type:	Submarine
Displacement:	Group 1: 520.6 long tons (529 t) surfaced 625 long tons (635 t) submerged Group 2: 491 long tons (499 t) surfaced 565 long tons (574 t) submerged
Length:	Group 1: 173 ft 4 in (52.83 m) Group 2: 175 ft (53 m)
Beam:	Group 1: 18 ft (5.5 m) Group 2: 16 ft 7 in (5.05 m)
Propulsion:	Group 1: 2 × 440 hp (328 kW) NELSECO diesel engines 2 × 370 hp (276 kW) New York Navy Yard (O1-O5) or Electro Dynamic Co. electric motors 2 × 60-cell batteries 2 × shafts Group 2: 2 × 500 hp (373 kW) Busch-Sulzer diesel engines 2 × 400 hp (298 kW) Diehl Manufacture Co. electric motors 2 × 60-cell batteries 2 × shafts
Speed:	Group 1: 14 knots (26 km/h; 16 mph) surfaced 10 knots (19 km/h; 12 mph) submerged Group 2: 14 knots (26 km/h; 16 mph) surfaced 11 knots (20 km/h; 13 mph) submerged
Range:	5,500 nmi (10,200 km) at 11.5 kn (21.3 km/h; 13.2 mph) surfaced 250 nmi (460 km) at 5 kn (9.3 km/h; 5.8 mph) submerged
Test depth:	200 ft (61 m)
Complement:	29
Armament:	4 × 18 inch (450 mm) torpedo tubes, 8 torpedoes 1 × 3 inch (76 mm)/23 caliber gun (retractable deck gun)

The United States Navy's sixteen O-class submarines were created out of the lessons learned from the L class. The O class were about 80 tons larger than the L class, with greater power and endurance for ocean patrols. Due to the American entry into World War I the O class were built much more rapidly than previous classes, and were all commissioned in 1918. O-1 through O-10 were group 1, designed by Electric Boat, O-11 through O-16 were group 2, designed by the Lake Torpedo Boat Company and sometimes considered a separate class. The group 2 boats entered service just before the end of World War I. Eight of the group 1 boats survived to serve in World War II as training boats when they were recommissioned in 1941.

The O class were built by five shipyards: O-1 by Portsmouth Navy Yard, Kittery, Maine, O-2 by Puget Sound Navy Yard, Bremerton, Washington, O-3 through O-10 by Fore River Shipyard, Quincy, Massachusetts, O-11 through O-13 by Lake Torpedo Boat Company, Bridgeport, Connecticut, and O-14 through O-16 by California Shipbuilding (formerly Craig Shipbuilding), Long Beach, California.

The class originally operated in the anti-submarine role off the United States's East Coast. Two of the boats, O-4 and O-6, came under fire from a British merchantman in the Atlantic on 24 July 1918. The steamer scored six hits on O-4's conning tower and pressure hull before her identity was discovered. O-4 suffered minor damage caused by shell splinters. O-3 to O-10 boats formed part of the twenty-strong submarine force that left Newport, Rhode Island on 2 November 1918 for the Azores, but the task force was recalled after the Armistice was signed nine days later.