SSBN-726 Ohio-Class FBM Submarines - Design Features

Fleet ballistic missile submarines (designated as "SSBNs") carry long-range nuclear warhead missiles. They roam the ocean avoiding contact with other submarines and surface ships. The ability of the fleet ballistic missile submarine to survive a nuclear attack against the United States made them the most credible nuclear deterrent during the Cold War. Fortunately, the threat of nuclear retaliation that US missile submarines have represented continues to be an effective deterrent in preventing nuclear missile attacks on the US.

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. Ballistic missile-launching nuclear-powered submarines (SSBNs) comprise the third element of the U.S. strategic TRIAD. Because these submarines carried about half of the warheads in the U.S arsenal in the later years of the Cold War, a measure of the ability to attack large numbers of targets, their destruction would be an especially important requirement for a successful Soviet damage-limiting strike.

the Trident SSBN measures 560 feet in length, has a diameter of 42 feet, and displaces 18,700 tons when submerged. It could carry 24 Trident I or II missiles. The large missile tubes of the Trident submarines were capable of housing a larger and more accurate Trident II missile. This missile, developed by the 1980s, offered an alternative means of developing a capability to attack Soviet ICBM silos in a second strike. The assignment of submarine-launched missiles to the counterforce role would require the procurement of additional submarines beyond those needed for retaliation against Soviet cities.

More than twice the size of a Poseidon submarine (8,250 tons displacement when submerged), the Trident (18,700 tons) will carry 24 missiles, eight more than either a Polaris or Poseidon ship. Although designed with the development of a new, large submarine-launched ballistic missile (SLBM) in mind, the Trident submarine will initially be armed with Trident I missiles, 6j which are small enough to fit the launch tubes of Poseidon ships as well. The launch tubes on the Trident SSBN could, however, house SLBMs some ten feet longer and 50,000 pounds heavier than the Trident I missile.

SSBNs are specifically designed for extended deterrent patrols. To increase the amount of time required for replenishment and maintenance, Ohio class submarines have three large-diameter logistics hatches that allow sailors to rapidly transfer supply pallets, equipment replacement modules and machinery components thereby increasing their operational availability.

The Ohio class design allows the submarines to operate for 15 or more years between major overhauls. On average, the submarines spend 77 days at sea followed by 35 days in-port for maintenance. Each SSBN has two crews, Blue and Gold, which alternate manning the submarines while on patrol. This maximizes the SSBN?s strategic availability, reduces the number of submarines required to meet strategic requirements and allows for proper crew training, readiness, and morale.

On U.S. Navy submarines, living quarters are called "berthing areas" that provide no more than 15 square feet of space per man for sleep and personal belongings. Each crewman's bed (called a bunk, berth or rack) has a reading light, a ventilation duct, an earphone jack for the ship's audio entertainment system, and a curtain to provide a small (but welcome) measure of privacy. The crewmen store their clothing and personal belongings in a sturdy pan-like locker beneath their mattress. When a U.S. Navy submarine is at sea, lights in the berthing areas are normally dimmed. About one third of the crew is asleep at a time because submarines operate 24 hours a day. The crew works in shifts, normally six hours on, 12 hours off. Only the captain and executive officer of the submarine have private rooms, called staterooms, in which to work and sleep. Sometimes, there are more people onboard than there are regular bunks. When this happens, a few of the crewmen have to sleep in makeshift bunks in the torpedo room. These temporary bunks are fitted on storage racks where torpedoes and missiles are normally kept. Space is always very limited on submarines, and there are very few large or open spaces where people can make a bed.

By 1980 significant cost increases and major delays in the Trident shipbuilding program prompted both the Congress and the Navy to look into the possibility of constructing smaller, cheaper submarines than the Trident. Doubts had also arisen about the need to develop the Trident II missile, in part because of its high near-term costs. The Trident II SLBM, however, would take full advantage of the Trident ship's large launch tubes, carrying a greater nuclear payload than the Trident I missile and probably incorporating greater accuracy.

Some skepticism also arises concerning whether a submarine much smaller than the Trident could accommodate all of the sound isolation mountings made possible by the Trident's large size. Advances have been made in quieting technology since the Trident was designed in the early 1970s, however. A new SSBN with quieting features nearly as successful as those of the Trident could perhaps be designed.

A submarine much smaller than a Trident probably could not, however, accommodate equally large logistics hatches and passageways and increased equipment accessibility. This might well prevent a comparable amount of ongoing repair and maintenance from being accomplished; a new SSBN might therefore have to spend more time in port than a Trident. Although, like the Trident, a new SSBN would probably be designed to operate for nine years between overhauls, The overhauls themselves might take several months longer, and "extended refit periods" (60-day mini-overhauls) might be required once or twice between normal overhauls. In addition, the replenishment and maintenance period (or "refit") following a patrol might last several days longer for a new SSBN than for a Trident ship.

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.

Navy commanders rely on the fleet’s submarine radio rooms to send and receive strategic and tactical command and control information, including messages to and from the National Command Authority. In a February 1995 mission need statement, the Navy identified the need for an updated, integrated exterior communications system, or radio room, on all submarine classes to support missions in the areas of command and control, intelligence, and logistics.

In order to keep the Submarine Force current with the rapidly improving state-of-the-art in communications, the Navy is transforming its antiquated communications architecture into one based on the commercial Internet Protocol (IP) model. In line with this transition, an integrated, open-systems approach will replace the existing “stove-pipe” architecture in submarine radio rooms and align with the quality of service and human systems integration goals embodied in Sea Power 21’s FORCENet vision. Space and Naval Warfare Systems Command’s Submarine Communication Program Office (SPAWAR PMW-173) is developing a Common Submarine Radio Room (CSRR) for all submarine classes in the fleet. Their goal is a common communications system that differs among submarines only when there are platform-unique considerations due to mission needs, external interfaces, and engineering factors.