SSN 790 South Dakota attack submarine delivered to US Navy.

The U.S. Navy has taken delivery of the SSN-790 “South Dakota”, the service’s seventeenth Virginia-class submarine. The Block III Virginia-class attack boat will be commissioned into service early in 2019.

SSN 790 "South Dakota" attack submarine (Picture source: US Naval Institute)

As reported by The National Interest, "South Dakota's delivery is an important milestone," Capt. Chris Hanson, Naval Sea Systems Command’s Virginia Class Program manager, said in a statement on September 24 when the service took delivery of the vessel. "It marks the penultimate Block III delivery and will be a vital asset in the hands of the fleet."

This submarine is the lead vessel for the Navy’s Acoustic Superiority Program. “This is our response to the continued improvement in our peer competitors’ submarine quality,” Rear Adm. Michael Jabaley, the Navy’s then program executive officer for submarines, already said on July 8, 2016, the Center for Strategic and International Studies. “The Russians with the production of the Severodvinsk SSGN took a significant step forward in their acoustic ability. We want to maintain pace ahead of that. We never want to reach acoustic parity, we always want to be better than anything any other country is putting out there in the submarine domain.”

South Dakota is expected to receive some fairly significant modifications from the baseline Virginia-class submarine that are expected to be tested at sea starting in 2019 and running through 2020. The modifications include new acoustical hull coatings, a series of machinery improvements inside the hull and the addition of two new large vertical sonar arrays—one on each side. The new sonar arrays “provide a significant advantage in the ability to detect other submarines before you yourself are in a position to be detected,” Jabaley said. Meanwhile, the machinery improvements also promise some “significant return on investment.”

Additionally, South Dakota will receive a new enhanced propulsor design, which is being added during construction. However, if the new propulsor design proves to be less than successful, the Navy plans to replace it during the boat’s post-shakedown availability. “ South Dakota will have an improved enhanced hybrid propulsor that we have developed with DARPA,” Jabaley said. “It promises to present a significant acoustic advantage.” If the modifications trialed on South Dakota prove to be successful, then the technologies will be adopted for use on future Virginia-class boats as well as the future Columbia-class ballistic missile submarines. “The lessons we learn, we will learn from her [South Dakota], will then drive what we install on future ships including Ohio Replacement and what we back-fit on existing Virginias,” Jabaley said.

The new quieting technology should more than mitigate any signature increase on the planned Block V Virginia-class submarines that will include the new Virginia Payload Module (VPM). The last 19 Virginia-class boats are all expected to carry the VPM missile tubes. After the last Virginia is built, the Navy expects to move onto a new attack submarine design.