USSO-1 (SS-62), lead ship of her class in dry dock at Portsmouth Navy 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	EB design: 520 long tons (528 t) surfaced 629 long tons (639 t) submerged Lake design: 485 long tons (493 t) surfaced 566 long tons (575 t) submerged
Length	EB design: 172 ft 4 in (52.53 m) Lake design: 175 ft (53 m)
Beam	EB design: 18 ft (5.5 m) Lake design: 16 ft 7 in (5.05 m)
Propulsion	EB design: 2 × 440 hp (328 kW)NELSECO 6-EB-14diesel engines 2 × 370 hp (276 kW)New York Navy Yard (O1-O5) orElectro Dynamic Co.electric motors 2 × 60-cellbatteries 2 × shafts Lake design: 2 × 500 hp (373 kW)Busch-Sulzer diesel engines 2 × 400 hp (298 kW)Diehl Manufacture Co. electric motors 1 × 120-cellbatteries 2 × shafts
Speed	EB design: 14knots (26 km/h; 16 mph) surfaced 10.5 knots (19.4 km/h; 12.1 mph) submerged Lake design: 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, 8torpedoes 1 ×3-inch (76 mm)/23-caliber gun (retractabledeck gun)[1]

TheUnited States Navy (USN)'s sixteen O-class coastal patrolsubmarines were built duringWorld War I and served the USN from 1918 through the end ofWorld War II.

Following the design trend of the day, these boats were scaled up versions of the precedingL class, reversing the fiscally created shrinkage in size of theN class.^[2] The O class were about 80 tons larger than the L class, with greater power and endurance for wider ranging patrols. Due to theAmerican entry into World War I the O class were built much more rapidly than previous classes, and were all commissioned in 1918.O-1 throughO-10 were designed byElectric Boat (EB),O-11 throughO-16 were designed by theLake Torpedo Boat Company and differed considerably from the EB design. All had the same military characteristics and performance and thus were considered by the Navy to be the same class. The EB design boats had a spindle shaped hull with an axially mountedrudder and twin lateral mountedpropeller shafts. The bowdiving planes controlled depth with the stern diving planes (mounted laterally behind the propellers) controlling the boat's angle while submerged. The Lake design also had a spindle shaped hull, but the rudder was ventrally mounted under the flat shovel-shaped stern with the propeller shafts also exiting the hull ventrally.^[3]

The EB design reverted to the semi-hemispherical rotating bow cap that covered the four 18-inch diametertorpedo tubes. Although a common feature on earlier EB submarines, this would prove to be the last of the EB designs with the cap.^[4] The Lake design used individual muzzle doors withhydro-dynamic shutters to seal the tubes, a feature that would become standard on all later USN submarines.^[5] These boats were big enough to have a semi-retractable3-inch/23-caliber gun on the deck forward of the conning towerfairwater. This gun partially retracted into a vertical watertight cylinder that penetrated the pressure hull into the forward battery compartment (EB design), or the control room (Lake design). When retracted the circular gun shield formed the top of the cylinder with only the barrel of the gun protruding above deck.^[6]

The Lake design retained Simon Lake's trademark amidships diving planes, theoretically used to enable zero-angle (a.k.a. even-keel) diving. This was a marked contrast to the angled-diving technique used by the EB design boats. Zero-angle diving proved to be unworkable and Lake used it here for the last time. His design for the follow-onR-class boats would abandon the method in favor of the EB angle-diving arrangement.^[7]

Unusually, the Navy obtained a legal license to build two of the EB design boats at government owned Navy Yards:O-1 byPortsmouth Navy Yard,Kittery, Maine, andO-2 byPuget Sound Navy Yard,Bremerton, Washington.O-3 throughO-10 of the EB design were built byFore River Shipyard,Quincy, Massachusetts.O-11 throughO-13 were Lake design built by theLake Torpedo Boat Company ofBridgeport, Connecticut. Once again desirous of having submarines built at a west coast yard, the Navy got Lake to build theO-14 throughO-16 at a sub-contractor named California Shipbuilding (formerlyCraig Shipbuilding),Long Beach, California.^[8][9] CALSHIP suffered from numerous management and production issues and all three boats assigned to them had to be towed up the coast to theMare Island Navy Yard north ofSan Francisco inVallejo, California for completion.^[10]

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

The Lake design boats (O-11 throughO-16), built by theLake Torpedo Boat Company andCraig Shipbuilding, suffered from electrical, structural, and mechanical problems.O-11 was immediately sent to thePhiladelphia Navy Yard for a five-month overhaul. In October 1918,O-13 sank the patrol boatMary Alice in a collision while she (O-13) was submerged.^[11]O-15 also underwent a refit but was sent into reserve soon after before she went into service atCoco Solo in thePanama Canal Zone. This also involved another overhaul.O-16 also underwent a refit soon after commissioning and later suffered a fire in her conning tower in December 1919. All six of the Lake design boats were decommissioned in July 1924, with five being scrapped in July 1930 under the terms of theLondon Naval Treaty. However, the decommissionedO-12 was leased back to Simon Lake for use in an Arctic expedition bySir Hubert Wilkins. Disarmed, she was rebuilt with specialized Arctic exploration equipment and renamedNautilus. After the conclusion of the expedition she was scuttled in a Norwegian fjord in November 1931 to keep within the provisions of the lease agreement, as the Navy no longer wanted her but didn't want the boat to fall into foreign hands.^[12]

The EB design boats served well althoughO-5 was rammed by a cargo ship and sunk near the Panama Canal on 28 October 1923 with the loss of three crew members. All nine of the surviving EB design boats were decommissioned into reserve status in 1931. The harsh economics of the Great Depression prevented proper pre-layup maintenance, and very little if any work was done on the boats during the nine years they laid in reserve at thePhiladelphia Navy Yard. Eight of the boats (O-1 had been scrapped in 1938) were refitted and recommissioned in 1941 to serve as training boats based at theNaval Submarine Base New London,Connecticut. The looming war emergency forced the work to be rushed, and many of the eight O-class still needed thorough maintenance after being recommissioned.O-9 sank during deep submergence trials in June 1941, likely due to her poor material condition. Thirty-three of her crew were lost.^[13]

In 1929–1930 the EB design O-class boats were modified for improved safety in the event of sinking. This was work prompted by the loss of theS-4 in 1927. Two marker buoys were added fore and aft. In the event the submarine was stranded on the bottom the buoys could be released to show the submarine's position. A motor room escape hatch was also added, the motor room being the after most compartment. The tapered after dorsal skeg became a step as a result of these modifications.^[14]

The 18-inch torpedo tubes of this class forced the Navy to retain the old Mk 7 torpedo, solely for the use by these boats. All other 18-inch torpedoes prior to the 21-inch Mk 8 were discarded before WWII as a cost saving measure.

During World War II, the seven remaining O boats were stationed at theNew London Submarine Base and served as training platforms for the Submarine School. The last O-boat,USS O-4, was decommissioned in September 1945.O-4 had served for 27 years and was, at that time, the longest serving submarine in the history of the US Navy.

The 16 submarines of the O class were:

Electric Boat (EB) design

Lake Torpedo Boat Company design

• List of lost United States submarines
• List of United States submarine classes

Wikimedia Commons has media related toO class submarines of the United States.

• Hutchinson, Robert (2001).Jane's Submarines : War Beneath the Waves From 1776 to the Present Day. London: HarperCollins.ISBN 9780007105588.
• Christley, Jim,US Submarines 1900-35 Osprey Publishing, 2011.ISBN 978-1-84908-185-6.
• Gardiner, Robert,Conway's All the World's Fighting Ships 1906–1921 Conway Maritime Press, 1985.ISBN 0-85177-245-5.
• Friedman, Norman "US Submarines through 1945: An Illustrated Design History", Naval Institute Press, Annapolis, 1995.ISBN 1-55750-263-3.
• NavSource early diesel submarines page
• PigBoats.COM O-class page
• DiGiulian, Tony Navweaps.com 3"/23 caliber gun
• ShipbuildingHistory.com Craig Shipbuilding page
•  This article incorporates text from thepublic domainDictionary of American Naval Fighting Ships.

• Submarine classes
• United States O-class submarines
• World War I submarines of the United States
• World War II submarines of the United States

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