List of Ohio - class submarines Named after its lead boat , the of nuclear - powered submarine s is , as of October 2013 , serving with its sole operator , the United States Navy . Fourteen of the eighteen boats are ballistic missile submarine s ( SSBN ) , which , along with U . S . Air Force strategic bomber s and intercontinental ballistic missiles , constitute the nuclear - deterrent triad of the U . S . The remaining four have been converted from their initial roles as SSBNs to cruise - missile carriers ( SSGN ) . The " Ohio " - class boats , each displacing 18 , 750 tons submerged , are the third largest submarines in the world , behind the 48 , 000 - ton Typhoon class and 24 , 000 - ton " Borei " class of the Russian Navy . The " Ohio " class replaced the " Benjamin Franklin " - and " Lafayette " - class SSBNs . The " Ohio " class was designed in the 1970s to carry the concurrently - designed Trident submarine - launched ballistic missile . Both variants of the Tridents — the UGM - 96 Trident I and the UGM - 133 Trident II — are propelled by three - stage solid propellant rockets and are equipped with 8 – 14 nuclear warhead s . The 73 , 000 lb ( 33 , 100 kg ) UGM - 96 , with a range of 4 , 000 mi ( 6 , 400 km ) , served from October 1979 , starting with the " Benjamin Franklin " - class USS " Francis Scott Key " , until 2006 . The 130 , 000 lb ( 59 , 000 kg ) UGM - 133 , with a range of 6 , 000 mi ( 9 , 700 km ) , is in service as of 2013 , having been introduced in 1990 with USS " Tennessee " . The primary self - defense weapon of the class is the Mk 48 ADCAP torpedo . " Ohio " - class submarines that carry ballistic missiles receive orders from the United States Strategic Command based in Nebraska . In 1994 , the Nuclear Posture Review study determined that , of the 18 " Ohio " SSBNs the U . S . Navy would be operating in total , 14 would be sufficient for the strategic needs of the U . S . The decision was made to convert four " Ohio " - class boats into SSGNs capable of conducting conventional land attack and special operations . As a result , the four oldest boats of the class — " Ohio " , " Michigan " , " Florida " , and " Georgia " — progressively entered the conversion process in late 2002 and were returned to active service by 2008 . The boats could thereafter carry 154 Tomahawk cruise missile s and 66 special operations personnel , among other capabilities and upgrades . The cost to refit the four boats was around US $ 1 billion ( 2008 dollars ) per vessel . With the first retirement of an " Ohio " - class boat scheduled for 2029 , the U . S . Navy is currently , as of January 2013 , undertaking a program tentatively named SSBN - X to study the prospective replacement of the class . Boats . In July 1974 , General Dynamics Electric Boat was awarded the contract to construct the " Ohio " - class submarines . The first of the class , USS " Ohio " , was laid down in 1976 . Due to an unspecified " series of unfortunate problems in Washington D . C . " and manufacturing issues , " Ohio " did not initiate sea trials until June 1981 , setting back the boat ' s commissioning date to November that year , three years behind schedule . Originally , it was decided that 20 boats were to be built , but due to the 1991 START I agreement between the U . S . and Soviet Union , the U . S . agreed to reduce the number of nuclear warheads it could deploy , and thus rationalized its order to 18 boats . The last boat of the class , USS " Louisiana " , was commissioned in September 1997 , nearly 16 years after the class entered operational service . Originally designed for 30 - year service lives , it was later decided that " Ohio " - class submarines would each serve for 42 years , comprising two periods of 20 years of operations and a two - year mid - life nuclear refueling . " Note : The classification of the 18 boats into the two U . S . fleets is according to the latest updates of the Naval Vessel Register , and does not indicate previous boat transfers between the two fleets . "