US Navy Ballistic Missile Ohio Class Submarines (SSBN)
The Ohio class is a class of nuclear-powered submarines used by the United States Navy. The United States has 18 Ohio-class submarines:
- 14 nuclear-powered SSBNs (ballistic missile submarines), each armed with up to 24 Trident II SLBMs; they are also known as "Trident" submarines, and provide the sea-based leg of the nuclear triad of the United States strategic nuclear weapons arsenal
- 4 nuclear-powered SSGNs (cruise missile submarines), each capable of carrying 154 Tomahawk cruise missiles with either conventional or nuclear warheads
The Ohio class is named after the lead submarine of this class, the USS Ohio (SSGN-726) formerly designated SSBN-726. The 14 Trident II SSBNs together carry approximately fifty percent of the total US strategic warhead inventory. The exact number varies in an unpredictable and classified manner, at or below a maximum set by various strategic arms limitation treaties. Although the missiles have no pre-set targets when the submarine goes on patrol, the platform, when required, is capable of rapid targeting using secure and constant at-sea communications links. The Ohio class is the largest type of submarine ever constructed for the U.S. Navy. Two Russian classes of submarines have larger total displacements: the Soviet-designed Typhoon class, which has more than twice the total displacement, and the Russian Federation's newest class of ballistic missile submarines, the highly advanced Borei class, which has roughly a 25% greater total displacement, but is shorter by 3 feet.
Ohios were specifically designed for extended deterrence patrols. Each submarine is complemented by two crews, Blue and Gold (standard practice for US FBMs), with each crew typically serving 70-90 day patrols. To decrease the time in port for crew turnover and replenishment, three large logistics hatches are fitted to provide large diameter resupply and repair openings. These hatches allow sailors to rapidly transfer supply pallets, equipment replacement modules, and machinery components, significantly reducing the time required for replenishment and maintenance. The class design allows the vessel to operate for over fifteen years between major overhauls. The boats are purported to be as quiet at their cruising speed of 20 knots (37 km/h; 23 mph) or more as previous subs were at a dead crawl of 6 knots (11 km/h; 6.9 mph), although exact information remains classified.
Ohios were constructed from sections of hull, each 42 ft (13 m) in diameter, each divided into four decks. The sections were produced at Quonset Point, Rhode Island, and assembled by Electric Boat at Groton. Fire control for the Mark 48 torpedoes is by Mark 118 Mod 2 system, while the Missile Fire Control (MFC) system is a Mark 98.
Except for USS Henry M. Jackson (SSBN-730), the Ohio class submarines are named after states in the United States.
- Overall Length: 560' - 0"
- Waterline Length: 560' - 0"
- Extreme Beam: 42' - 0"
- Waterline Beam: 42' - 0"
- Max. Navigational Draft: 38' - 0"
- Light Displacement: 15,275 tons
- Full Displacement: 16,802 tons
- Structural Composition: Steel
- Number of Propellers 1
- Propulsion Type: 1 General Electric S8G Reactor powering 2 Steam Turbines
- Total Shaft Horsepower: UNAVAILABLE
- Speed: 20+ knots submerged
- Crew (typ.): Officers: 13; Enlisted: 141
The first eight Ohio class submarines were originally equipped with up to 24 Trident I (C4) submarine-launched ballistic missiles. Beginning with the ninth Trident submarine, USS Tennessee (SSBN-734), the remaining boats were equipped with the upgraded Trident II (D5). The Trident II missile carries eight multiple independently targetable reentry vehicles (MIRVs), in sum delivering more deterrence than the Trident I and with much greater accuracy. Starting with USS Alaska (SSBN-732) in 2000, the Navy began converting the remaining C4-equipped submarines to D5 missiles; this was completed in mid-2008.
The first eight boats were homeported in Bangor, Washington to replace the Polaris (A3) carrying submarines that were then being decommissioned. The remaining ten boats were originally homeported in Kings Bay, Georgia, replacing the Atlantic-based Poseidon and Trident Backfit submarines. During the conversion of the first four hulls to SSGNs (see below), five boats, Pennsylvania, Kentucky, Nebraska, Maine and Louisiana, were shifted from Kings Bay to Bangor. Further shifts are occurring as the United States' strategic needs change.
Ohio SSGN conversion
After the end of the Cold War, plans called for Ohio to be retired in 2002, followed by three of her sisters. However, Ohio, Michigan, Florida and Georgia instead were slated for modification, to remain in service carrying conventionally-armed guided missiles, and were designated SSGNs.
Beginning in 2002 through 2010, 22 of the 24 88-inch (2.2 m) diameter Trident missile tubes were modified to contain large vertical launch systems (VLS), one configuration of which may be a cluster of seven Tomahawk cruise missiles. In this configuration, the number of cruise missiles carried could be a maximum of 154, the equivalent of what is typically deployed in a surface battle group. Other payload possibilities include new generations of supersonic and hypersonic cruise missiles, and Submarine Launched Intermediate Range Ballistic Missiles (SLIRBM), unmanned air vehicles (UAVs), the ADM-160 MALD, sensors for anti-submarine warfare or intelligence, surveillance and reconnaissance missions, counter-mine warfare payloads such as the AN/BLQ-11 Long Term Mine Reconnaissance System (LMRS), and the broaching universal buoyant launcher (BUBL) and stealthy affordable capsule system (SACS) specialized payload canisters.
The missile tubes also have room for stowage canisters that can extend the forward deployment time for special forces. The other two Trident tubes are converted to swimmer lockout chambers. For special operations, the Advanced SEAL Delivery System and the Dry Deck Shelter can be mounted on the lockout chamber and the boat will be able to host up to 66 special operations sailors or Marines, such as Navy SEALs. Improved communications equipment installed during the upgrade allows the SSGNs to serve as a forward-deployed, clandestine Small Combatant Joint Command Center.
On 26 September 2002, the Navy awarded the Electric Boat company a $442.9 million contract to begin the first phase of the SSGN submarine conversion program. Those funds covered only the initial phase of conversion for the first two boats on the schedule. Advanced procurement was funded at $355 million in fiscal year 2002, $825 million in the FY 2003 budget and, through the five-year defense budget plan, at $936 million in FY 2004, $505 million in FY 2005, and $170 million in FY 2006. Thus, the total cost to refit the four boats is just under $700 million per vessel.
In November 2002, the USS Ohio entered drydock, beginning her 36-month refueling and missile conversion overhaul. Electric Boat announced on 9 January 2006 that the conversion had been completed. The converted Ohio rejoined the fleet in February 2006, followed by the USS Florida in April 2006. The converted USS Michigan was delivered in November 2006. The converted Ohio went to sea for the first time in October 2007. The Georgia returned to the fleet in March 2008 at Kings Bay. These four SSGNs are expected to remain in service until about 2023-2026.
The Department of Defense anticipates a continued need for a sea-based strategic nuclear force. The first of the current Ohio SSBNs are expected to be retired by 2029, meaning that a platform must already be seaworthy by that time. A replacement may cost over $4 billion per unit compared to Ohio's $2 billion. The Navy is exploring two options. The first is a variant of the Virginia-class nuclear attack submarines. The second is a dedicated SSBN, either with a new hull or based on an overhaul of the current Ohio.
With the cooperation of both Electric Boat and Newport News Shipbuilding, in 2007 the Navy had already begun a cost control study. Then in December 2008 the Navy awarded Electric Boat a contract for the missile compartment design of the Ohio class replacement, worth up to $592 million. Newport News is expected to receive close to 4% of that project. Though the Navy has yet to confirm an Ohio class replacement program, Defense Secretary Robert M. Gates, as of April 2009, confirms that the Navy should begin such a program in 2010. The new vessel is scheduled to enter the design phase by 2014. It is anticipated that if a new hull design is used the program must be initiated by 2016 in order to meet the 2029 deadline.
Rep. Gene Taylor of Mississippi had threatened to block the project unless the Navy shares with the Congress an internal Analysis of Alternatives.