Details: The Ohio replacement ballistic missile submarine

From Next Big Future

06 March 2015

The U.S. Navy operates three kinds of submarines -- nuclear-powered attack submariens (SSNs), nuclear-powered cruise missile submarines (SSGNs), and nuclear-powered balistic missile submarines (SSBNs).

The SSNs and SSGNs are multi-mission ships that perform a variety ofpeacetime and wartime missions. They do not carry nuclear weapons.

The Ohio replacement program (ORP) is a program to design and build a new class of 12 ballistic missile submarines (SSBNs) to replace the Navy’s current force of 14 Ohio-class SSBNs. The Ohio replacement program is also known as the SSBN(X) program. The Navy wants to procure the first Ohio replacement boat in FY2021, with advance procurement (AP) funding starting in FY2017. The Navy has identified the Ohio replacement program as its top priority program.

The Navy currently operates 14 Ohio (SSBN-726) class SSBNs. The boats are commonly called Trident SSBNs or simply Tridents because they carry Trident SLBMs.

Ohio-class SSBNs are designed to each carry 24 SLBMs, although by 2018, four SLBM launch tubes on each boat are to be deactivated, and the number of SLBMs that can be carried by each boat consequently is to be reduced to 20, so that the number of operational launchers and warheads in the U.S. force will comply with strategic nuclear arms control limits.

The first eight boats in the class were originally armed with Trident I C-4 SLBMs; the final 10 were armed with larger and more-capable Trident II D-5 SLBMs

• The SSBN(X) is to be equipped with an electric-drive propulsion train, as opposed to the mechanical-drive propulsion train used on other Navy submarines. The electric-drive system is expected to be quieter (i.e., stealthier) than a mechanical-drive system.

 Electric drive is a propulsion system that uses an electric motor which turns the propeller of a ship/submarine. It is part of a wider (Integrated electric power) concept whose aim is to create an "all electric ship". Electric drive should reduce the life cycle cost of submarines while at the same time improving acoustic performanc

• The SSBN(X) is to have SLBM launch tubes that are the same size as those on the Ohio class (i.e., tubes with a diameter of 87 inches and a length sufficient to accommodate a D-5 SLBM).

• The SSBN(X) will have a beam (i.e., diameter) of 43 feet, compared to 42 feet on the Ohio-class design, and a length of 560 feet, the same as that of the Ohioclass design.

• Instead of 24 SLBM launch tubes, as on the Ohio-class design, the SSBN(X) is to have 16 SLBM launch tubes.

• Although the SSBN(X) is to have fewer launch tubes than the Ohio-class SSBN, it is to be larger than the Ohio-class SSBN design, with a reported submerged displacement of 20,815 tons (as of August 2014), compared to 18,750 tons for the Ohio-class design.

• The Navy states that “owing to the unique demands of strategic relevance, [SSBN(X)s] must be fitted with the most up-to-date capabilities and stealth to ensure they are survivable throughout their full 40-year life span

Sensors: SSBN-X is expected to use the horseshoe-shaped Large Aperture Bow Array (LAB) sonar that was developed for the Virginia Block III submarines. The submarines will undoubtedly deploy an array of other sensors, including flank sonars, towed sonar, fiber-optic masts that don’t have to penetrate the ship’s hull, ESM signal recognition and location technologies, etc.

The key will be making these sensors upgradeable at low cost. The 65 years from 2015 – 2080 is a huge amount of time in the technology world. If upgrades are too expensive, the entire SSBN force could find itself compromised mid-way through its life.

There will be non-nuclear payloads in some of the missile tubes. Converted Ohio class SSGNs, for instance, have already replaced nuclear missiles with American special forces, land attack missiles, and UAVs. In a similar and related vein, the Virginia Class Block III fast attack submarine replaced their 12 vertical-launch cruise missile tubes with 2 Common Weapon Launcher (CWL) “six-shooters” derived from the SSGNs’ converted missile tubes. The size of those CWLs allows Virginia Class Block III submarines to launch cruise missiles, UAVs, UUVs, and more from these same tubes.