Lafayette (SSBN 616)

These 31 submarines were the definitive production launch platforms for the Polaris Submarine-Launched Ballistic Missile (SLBM) design. The program is nearly unique in its success in getting so many complex ships in service in so short a time.
These submarines are enlarged and improved versions of the previous Ethan Allen (SSBN 608) class. Their main armament upon completion was the Polaris A-2 and A-3 SLBMs. From 1970 to 1978, all 31 boats were converted to fire the Poseidon C3, which was fitted with Multiple Independently Targetable Reentry Vehicles (MIRV). James Madison (SSBN 627) deployed on the first Poseidon patrol in March 1971. In a second upgrade, 12 submarines were upgraded to fire the longer-range Trident C-4 missile from 1979 to 1982. Francis Scott Key (SSBN 657) was the first to deploy Tridents in October 1979, the George Bancroft (SSBN 643) the last of the 12 in June 1989.
As in the Ethan Allen class, the pressure hulls are constructed of HY-80 steel. The Lafayett&cl&ss operating depth is probably deeper than that of the later Ohio (SSBN 726) class. The last 12 submarines of this class had quieter machinery installations and other minor differences and were officially designated as the Benjamin Franklin class. (The Daniel Wfefeter/SSBN 626 had bow-mounted diving planes instead of sail planes as in all other US SSBNs; she was retrofitted with sail planes before her decommissioning.)
Lafayettes navigated through two Mk 2 Mod 6 Ship’s Inertial Navigation Systems (SINS), which were augmented by an Electrostatically Supported Gyro Monitor (ESGM) fitted first to the Trident boats and later to the 19 Poseidon craft.


An indication of the urgency with which they were procured is the furious building rale, with the first being ordered in July 1960 (completion in April 1963) and the 31st finishing up less than seven years later, in April 1967. Four shipyards participated in the program: General Dynamics’ Electric Boat in Groton, Connecticut (13 boats), Newport News Shipbuilding (10), Mare Island Navy Yard (six), and Portsmouth Navy Yard (two),
Designed originally for a 20-year service life, most of the class was retired well before their 30th birthday.
The Mariano Vallejo (SSBN 658) was credited with completing the 2,500th SSBN patrol on April 4, 1987. Decommissioning of this class began in 1986 with the Nathan Hale (SSBN 623) and
Nathanael Greene (SSBN 626). The last went into mothballs in 1994.


DISPLACEMENT surfaced 7,310-7,350
tons; submerged 8,260 tons (SSBN 616-626), 8,240 tons (627-639),
8,250 tons (640-659)
length 425 ft (129.6 m) overall beam 33ft (10.1 m)
draft 31 ft 6 in (9.6 m)
MACHINERY 1 Westinghouse S5W pressurized-water reactor, 2 steam turbines, 15,000 shp on 1 shaft=20 kts (surfaced), 25 kts (submerged)
CREW 140-146
16 tubes for Poseidon C-3/Trident
C-4 SLBM 4 21-in (533-mm) Mk 65 bow torpedo
tubes with Mk 48 torpedoes
BPS-11 /11A or BPS-15 surface-search radar
BQR-7 passive sonar BQR-15 towed-array sonar BQR-19 navigation sonar BQR-21 passive array sonar BQS-4 active/passive detection sonar WLR-8 passive intercept EW system

Ohio (SSBN 726)

These 18 launch platforms for Trident Submarine-Launched Ballistic Missiles (SLBM) are the largest submarines built in the United States, although the Soviet Typhoon SSBNs are almost half again as large. The Ohios have four more missile launch tubes than the Typhoons, but, unlike the Russian boats, are of an evolutionary, rather than radically new, design. For example, they retain the bow sonar dome and amidships torpedo tubes of later attack submarines (SSN).
The first eight Ohios are armed with the Trident C-4 missile, which was also deployed on 12 Lafayett&cl&ss SSBNs. The Tennessee (SSBN734) and laterboats have the Trident D-5 missile, which was to be fitted into the earlier craft during subsequent overhauls. Those refits were canceled due to the decline in the nuclear deterrent posture as well as the cessation of the D-5′s W88 warhead production because of safety problems at the Rocky Flats plant. In fact, only 400 W88 war-heads were completed, not enough to outfit all D-5s being built.
The first eight boats have two Mk 2 Mod 7 Ship’s Inertial Navigation Systems
(SINS) with the Electrostatically Supported Gyro Monitor (ESGM). Beginning with the Tennessee, the heart of the navigation system is the Electrostatically Supported Gyro Navigator (ESGN). The Navigation Sonar System (NSS), also fitted to these boats, has a better ability to measure velocity than earlier systems.
Reportedly, the Ohiois significantly quieter than the ship’s design goals for self-quieting. At low speeds, when using natural convection rather than pumps for the circulation of pressurized water in the primary loop, the Ohio may be the quietest nuclear submarine yet constructed. As the nuclear threat waned, this attribute, and the class’s relative youth, led to a suggestion that some of the earlier boats be retired or rearmed as Tomahawk cruise missile carriers.


A force of 20 Ohio-class Trident submarines was originally planned. Because of budget cuts and the uncertainty of SSBN force requirements in light of ongoing arms control talks, the number of submarines was cut to 18. The Ohio was ordered in January 1974 but wasn’t commissioned until April 1981 because of design changes, program mismanagement, and problems at the Electric Boat shipyard in Groton, Connecticut. A late-1980s Navy attempt to force competition between Electric Boat and Newport News Shipbuilding failed when EB’s edge as lead yard proved too great to overcome.
The first squadron of Ohios (Submarine Squadron 17) operates in the Pacific, based at Bangor, Washington, and established on January 5, 1981. The second 0/Mo-class submarine squadron was formed in the Atlantic, based at Kings Bay, Georgia; the Tennessee (SSBN 734) was the first submarine to be assigned there. These submarines conduct 70-day patrols interrupted by 25-day overhaul/ replenishment periods, during which time the blue/gold crews change over. Under this schedule the submarines undergo a lengthy overhaul and reactor refueling every 10 years.


DISPLACEMENT 16,764 tons standard, 18,750 tons submerged
length 560 ft (170.7 m) overall beam 42 ft (12.8 m)
draft 36 ft 5 in (ll.lm)
MACHINERY 1 General Electric S8G pressurized-water reactor, 2 General Electric steam turbines, 60,000 shp on 1 shaft=18 kts surface, 30 kts submerged
24 tubes for Trident C-4 SLBM in SSBN 726-733
24 tubes for Trident D-5 SLBM in later units
4 21-in (533-mm) Mk 68 torpedo tubes amidships for Mk 48 torpedoes
BPS-15A surface-search radar (being
replaced by Sperry BPS-16) BQQ-6 bow-mounted sonar BQR-19 navigation sonar BQS-13 active detection sonar BQS-15 under-ice sonar TB-16 or TB-29 towed-array sonar WLR-8 (V)5 radar-warning system

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