The U.S. Navy is mulling a plan to build a new class of guided-missile submarines to replace today’s four-strong Ohio-class SSGNs beginning in the 2030s. The sailing branch is worried that not replacing the SSGNs could exacerbate a looming, medium-term reduction in undersea cruise-missile capacity.

The Tactical Submarine Evolution Plan, which the service finished in the fall of 2017, explores the possibility of modifying the new Columbia-class ballistic-missile sub design to produce a new SSGN. The idea would be to build new guided-missile boats at the end of the Columbia class’s 12-ship production run, thus taking advantage of existing manufacturing processes.

Preserving the hot SSBN line for SSGNs would also ensure that the Navy has two active submarine production lines — one each for big missile boats and smaller attack boats — through the 2020s and 2030s, rather than the one SSN line it would possess under older plans.

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“There is value in keeping two product lines going,” Brian Howes, director of the Navy’s undersea warfare directorate, told USNI News. “You never want to start up and shut down product lines, so the big-volume ship is one we’re interested in exploring after we complete our buy of Columbia.”

The first of the 560-foot-long Columbia-class boats is scheduled to begin production in 2021 and enter service in 2031. The final new SSBN should begin construction in 2035, at which point America’s two submarine-builders — Electric Boat in Connecticut and Newport News in Virginia — will possess the facilities and skilled manpower to efficiently produce guided-missile subs based on the Columbia design.

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The current SSGNs are modifications of the four oldest Ohio-class SSBNs. In the early 2000s the Navy replaced 22 of each boats’ 24 ballistic-missile launch-tubes with clusters of seven vertical launchers for Tomahawk conventional cruise missiles, giving each boat the ability to carry as many as 154 Tomahawks. In 2011 the SSGN USS Florida quickly launched scores of Tomahawks to carve a path through Libya’s air defenses in the early hours of the international intervention in that country’s civil war.

The roughly 600 cruise-missile tubes aboard the four SSGNs represent around half of the Navy’s undersea conventional missile capacity. Missile tubes aboard Los Angeles-, Seawolf– and Virginia-class attack submarines account for the other half. The fleet’s submarines plus its approximately 90 cruisers and destroyers together boast around 9,000 missile tubes that are compatible with Tomahawks.

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When the old SSGNs retire in the late 2020s, the Navy will quickly lose a large proportion of its Tomahawk launchers.

The Navy already plans to mitigate the missile gap by adding launch tubes to at least 20 Virginias starting in 2019. Early Virginias from production blocks one through four — the Navy has commissioned or ordered 28 of these boats — pack 12 Tomahawk tubes in their bows. The new Block V version adds four seven-tube missile clusters for a total Tomahawk capacity of 40 per sub.

Once all 20 new Virginias have entered service around 2035, the Navy should regain the launch capacity it will have lost with the retirement of the Ohio-class SSGNs. Building new SSGNs on the hot Columbia line could grow the branch’s missile capacity above 2017 levels — and buttress against the retirement of older SSNs in the 2040s and beyond.

This first appeared in WarIsBoring here. 

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