History of Ohio-class submarine in Timeline

By Popular Timelines Editorial Team · Updated: May 11, 2026

The Ohio-class submarine is the largest submarine ever built for the US Navy, displacing 18,750 tons submerged. There are 18 total, with 14 configured as ballistic missile submarines (SSBNs) capable of carrying 24 Trident II missiles and 4 configured as cruise missile submarines (SSGNs) carrying 22 tubes with 7 Tomahawk cruise missiles apiece. It is the third-largest submarine ever constructed, behind the retired Soviet-era Typhoon class and the Borei class.

1982: Sea Trials of Ohio

In 1982, the Ohio submarine completed her sea trials and was virtually undetectable, which gave the U.S. Navy extremely advanced flexibility.

1994: Nuclear Posture Review Study

In 1994, the Nuclear Posture Review study determined that 14 Ohio SSBNs would be sufficient for the strategic needs of the U.S.

2000: Conversion to D5 Missiles begins

In 2000, the Navy began converting its remaining ballistic missile submarines armed with C4 missiles to carry D5 missiles, starting with Alaska.

September 2002: Contract Awarded for SSGN Conversion Program

On 26 September 2002, the Navy awarded General Dynamics Electric Boat a US$442.9 million contract to begin the first phase of the SSGN submarine conversion program.

November 2002: Ohio Enters Dry-Dock

In November 2002, the Ohio submarine entered a dry-dock, beginning her 36-month refueling and missile-conversion overhaul.

2002: Ohio-class boats enter conversion process

In late 2002, the four oldest Ohio-class boats—Ohio, Michigan, Florida, and Georgia—progressively entered the conversion process to SSGNs.

2003: SSGN Conversion Advance Procurement Funding

In fiscal year 2003, $825 million was budgeted for advance procurement for the SSGN conversion program.

2004: SSGN Conversion Advance Procurement Funding

In fiscal year 2004, $936 million was budgeted for advance procurement for the SSGN conversion program.

2005: SSGN Conversion Advance Procurement Funding

In fiscal year 2005, $505 million was budgeted for advance procurement for the SSGN conversion program.

January 2006: Conversion of Ohio Completed

On 9 January 2006, Electric Boat announced that the conversion of the Ohio submarine had been completed.

February 2006: Ohio Rejoined Fleet

In February 2006, the converted Ohio submarine rejoined the fleet.

April 2006: Florida Rejoined Fleet

In April 2006, the converted Florida submarine rejoined the fleet.

November 2006: Michigan Delivered

In November 2006, the converted Michigan submarine was delivered.

2006: SSGN Conversion Advance Procurement Funding

In fiscal year 2006, $170 million was budgeted for advance procurement for the SSGN conversion program.

October 2007: Ohio Goes to Sea

In October 2007, the converted Ohio submarine went to sea for the first time.

2007: Cost-Control Study

In 2007, the U.S. Navy began a cost-control study with the cooperation of both Electric Boat and Newport News Shipbuilding.

March 2008: Georgia Returned to Fleet

In March 2008, the Georgia submarine returned to the fleet at Kings Bay.

December 2008: Contract for Missile Compartment Design

In December 2008, the U.S. Navy awarded Electric Boat a contract for the missile compartment design of the Ohio-class replacement, worth up to $592 million.

2008: Ohio-class boats return to active service

By 2008, the four oldest Ohio-class boats—Ohio, Michigan, Florida, and Georgia—were returned to active service after conversion to SSGNs.

2008: Conversion to D5 Missiles Completed

In mid-2008, the Navy completed the conversion of its remaining ballistic missile submarines armed with C4 missiles to carry D5 missiles.

April 2009: Program Initiation

In April 2009, U.S. Defense Secretary Robert M. Gates stated that the U.S. Navy was expected to begin a program for the Ohio-class replacement in 2010.

2010: Expected Program Start

In 2010, the U.S. Navy was expected to begin a program for the Ohio-class replacement.

2011: Deterrent Patrols

In 2011, Ohio-class submarines carried out 28 deterrent patrols.

June 2014: Longest Patrol

From January to June 2014, the Pennsylvania submarine carried out a 140-day-long patrol, the longest to date.

2014: Scheduled Design Phase

By 2014, the new vessel for the Ohio-class replacement was scheduled to enter the design phase.

December 2016: Columbia Class Designation

On 14 December 2016, the Columbia class was officially designated by Secretary of the Navy Ray Mabus, and the lead submarine will be USS District of Columbia (SSBN-826).

2016: Initiation Deadline

If a new hull design was to be used for the Ohio-class replacement, the program needed to be initiated by 2016 to meet the 2029 deadline.

2017: Deactivation of Missile Tubes

In 2017, as part of the New START treaty, four missile tubes on each SSBN were deactivated, reducing the number of missiles to 20 per boat.

2020: Discussion of Ohio-class Life Extension

In 2020, Navy officials first publicly discussed the idea of extending the lives of select Ohio-class boats at the Naval Submarine League's 2020 conference.

2022: Further Discussion of Ohio-class Life Extension

During the 2022 Naval Submarine League conference, officials discussed the Columbia-class program and the possibility of extending the lives of Ohio-class boats with sufficient remaining nuclear fuel and in good material state.

2023: Retirement of Typhoon class submarine

In 2023, the Russian Navy retired the last of its Soviet era 48,000-ton Typhoon class submarines, which were the largest submarines ever built, surpassing the Ohio-class in size.

2023: Expected End of Service for SSGNs

The four SSGNs are expected to remain in service until about 2023–2026, after which their capabilities will be replaced with Virginia Payload Module-equipped Virginia-class submarines.

2026: Expected End of Service for SSGNs

The four SSGNs are expected to remain in service until about 2023–2026, after which their capabilities will be replaced with Virginia Payload Module-equipped Virginia-class submarines.