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SSBN-726 Ohio-Class FBM Submarines

Strategic deterrence has been the sole mission of the fleet ballistic missile submarine (SSBN) since its inception in 1960. The SSBN provides the nation's most survivable and enduring nuclear strike capability. The Ohio class submarine replaced aging fleet ballistic missile submarines built in the 1960s and is far more capable.

Naval Submarine Base Kings Bay hosted the commissioning of USS LOUISIANA (SSBN 743) 06 September 1997 at the TRIDENT Refit Facility Drydock. The commissioning of LOUISIANA completed the Navy's fleet of 18 fleet ballistic missile submarines. The ten Trident submarines in the Atlantic fleet were initially equipped with the D-5 Trident II missile. The eight submarines in the Pacific were initially equipped with the C-4 Trident I missile. In 1996 the Navy started to backfit the eight submarines in the Pacific to carry the D-5 missile.

Features

A streamlined (fish-shaped) outer hull permits the ship to move quietly through the water at high speeds. This outer hull surrounds the forward and aft end of the pressure hull and is not built to withstand deep submergence pressure. It is normally considered as the main ballast tanks. The superstructure is any part of the ship that is above the pressure hull. This would include the sail or fairwater area, and the area above the missile tubes. The streamlined hull was designed specifically for efficient cruising underwater; the Skipjack was the first nuclear-powered ship to adopt this hull form.

The larger hulls accommodate more weapons of larger size and greater range, as well as sophisticated computerized electronic equipment for improved weapon guidance and sonar performance. Improved silencing techniques reduce the chances of detection.

The Ohio-class submarines are specifically designed for extended deterrent patrols. To increase 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 and modern main concepts allow the submarines to operate for 15+ years between overhauls. Each SSBN is at sea at least 66 percent of the time, including major overhaul periods of twelve months every nine years. One SSBN combat employment cycle includes a 70-day patrol and 25-day period of transfer of the submarine to the other crew, between-deployment maintenance, and reloading of munitions.

Like all submarines in use by the U.S. Navy today, the Ohio class submarine is powered by a pressurized water reactor (PWR) driving steam turbines to a single propeller shaft. It can attain depths in excess of 800 feet at speeds in excess of 25 knots.

Background

The Navy (SSPO) commenced studies of a new Undersea Long-range Missile System (ULMS), which culminated in the Deputy SECDEF approving a Decision Coordinating Paper (DCP) No. 67 on 14 September 1971 for the ULMS. The ULMS program was a long-term modernization plan which proposed development of a new, longer-range missile and a new, larger submarine, while preserving a nearer-term option to develop an extended range POSEIDON. In addition to the new ULMS (extended-range POSEIDON) missile, which was to achieve a range twice that of POSEIDON, the SECDEF decision described an even longer-range missile to be required for a new submarine, whose parameters it would, in part, determine. This second missile, subsequently termed ULMS II, was to be a larger, higher-performance missile than the extended-range POSEIDON and to have a range capability of approximately 6000 nm. The term TRIDENT (C4) replaced the extended-range missile (Advanced POSEIDON) nomenclature in May 1972, and the name TRIDENT II was used to designate the new longer range missile.

On 14 September 1971 the Deputy SECDEF had approved the Navy's DCP No. 67, which authorized both a new, large, higher-speed submarine and the TRIDENT (C4) Missile System. It was also constrained to fit in the circular SSBN cylinder launch tube which just contained the C3 so that the new missile could be used in then-existing POLARIS submarines.

A Navy decision was made in November 1971 to accelerate the ULMS program with increased funding for the ULMS SSBN. The SECDEF Program Budget Decision (PBD) of 23 December 1971 authorized the accelerated schedule with a projected deployment of the ship in 1978.

The President signed the FY74 Appropriations Authorization Act providing funds for the first TRIDENT submarine on 15 November 1973, and on 25 July 1974 the Navy awarded a fixed-price incentive contract to General Dynamics, Electric Boat Division, for construction of this first TRIDENT SSBN.

In 1974 the initial Ohio program was projecte to consist of 10 submarines deployed at Bangor Washington carrying the Trident-1 C-4 missile. By 1981 the program had been modified to include 15 boats, and at least 20 boats were planned by 1985. In 1989 the Navy anticipated a total fleet of at least 21 boats, while plans the following year envisioning a total of 24 boats, 21 of which would carry strategic missiles with the remaining three supporting other missions, such as special forces. However, in 1991 Congress directed the termination of the program with the 18th boat, citing anticipated force limits under the START-1 arms control agreement and the results of the Bush Administration's Major Warship Review, which endorsed capping the program at 18 boats.

The first eight Ohio class submarines (Tridents) were originally equipped with 24 Trident I C-4 ballistic missiles. Beginning with the ninth Trident submarine, USS Tennessee (SSBN 734), all new ships are equipped with the Trident II D-5 missile system as they were built, and the earlier ships are being retrofitted to Trident II. Trident II can deliver significantly more payload than Trident I C-4 and more accurately. All 24 missiles can be launched in less than one minute.

Ohio-class/Trident ballistic missile submarines provide the sea-based "leg" of the triad of U.S. strategic offensive forces. By the turn of the century, the 18 Trident SSBNs (each carrying 24 missiles), will carry 50 percent of the total U.S. strategic warheads. Although the missiles have no pre-set targets when the submarine goes on patrol, the SSBNs are capable of rapidly targeting their missiles should the need arise, using secure and constant at-sea communications links.

The Clinton Administration's Nuclear Posture Review was chartered in October 1993, and the President approved the recommendations of the NPR on September 18, 1994. As a result of the NPR, US strategic nuclear force structure will be adjusted to 14 Trident submarines -- four fewer than previously planned -- carrying 24 D-5 missiles, each with five warheads, per submarine. This will require backfitting four Trident SSBNs, currently carrying the Trident I (C- 4) missile, with the more modern and capable D-5 missile system. Under current plans, following START II's entry into force, the other four SSBNs will either be converted into special-purpose submarines or be retired.

SSBN 726 Class Submarine shipboard equipment which requires significant maintenance during the planned operating cycle, industrial level maintenance, which is beyond the capability of Ship's Force, and which cannot be accomplished during the refit period (without unacceptable impact on other refit requirements), is supported by TRIDENT Planned Equipment Repair (TRIPER) program. TRIPER equipment is removed from the ship for refurbishment ashore, replaced with pre-tested, Ready for Issue units and the affected system restored to full operational condition prior to completion of the refit period. Replacement is accomplished on a planned basis at intervals designed to preclude the failure of the equipment or significant degradation of its associated system.

Recent Developments

As of 1995 the Navy was studying an extension from 30 to 40 years for the SSBN-726 class submarines. While 30 years was long the standard number for submarine operating lifetime, the SSBNs would seem to have a rather more benign operating history than the SSNs. They typically operate at somewhat shallower depths, they do not experience nearly as many excursions from their normal operating depth, and they would not operate below their test depth with any degree of freqency. Consequently, it would be expected that they could have a longer operating life than attack submarines [just as fighters wear out so much faster than bombers or transports]. As of late 1998 Navy cost and planning factors assumed that the Ohio-class submarines would have an expected operating lifetime of at least 42 years: two 20-year operating cycles separated by a two-year refueling overhaul.

As part of its long-term plan to divide the Trident fleet equally between the Atlantic and Pacific fleets, beginning in 2002 the Navy will transfer three of the 10 Trident subs now based at King's Bay to Bangor. Of the eight Trident submarines assigned to Bangor -- USS Alaska, USS Nevada, USS Henry M. Jackson and USS Alabama -- will convert from the older Trident I (C-4) missile to the more powerful Trident II (D-5) missile. The Nevada is scheduled to enter the Bremerton shipyard in early 2001 to begin its conversion, and the final pair are scheduled for the refitting in 2005 and 2006.

Sources and Resources

• FY1996 Ships Class Average Report Navy Visibility and Management of Operating and Support Costs (VAMOSC)
• Fleet Ballistic Missile Submarines SSBN - Navy FactFile
• United States Navy Ballistic Missile Submarines
• Commander Submarine Group 9 Naval Submarine Base, Bangor, Washington
• Naval Submarine Base, Kings Bay, Georgia
• TRIDENT Planned Equipment Replacement (TRIPER) Program

• SSBN 726 OHIO CLASS Sturgeon Submarine Journal
• Ohio Class Submarine - Paul A. Larkin
• USS Wyoming (SSBN 742)

• REFITTING TRIDENT SUBS FOR CONVENTIONAL WARFARE Mr. PELL - Congressional Record (Senate - January 29, 1991)
• BUMPERS AMENDMENT NO. 2398 -- DEPARTMENT OF DEFENSE APPROPRIATIONS ACT, 1996 (Senate - August 11, 1995)
• AMENDMENT NO. 6 OFFERED BY MR. LUTHER - TERMINATION OF NEW PRODUCTION OF TRIDENT II (D-5) MISSILES - NATIONAL DEFENSE AUTHORIZATION ACT FOR FISCAL YEAR 1998 (House of Representatives - June 20, 1997)
• TRIDENT Hull and Missile Life Extensions Approved Undersea Warfare Fall 1998 Vol. 1, No. 1

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