Navy’s Huge Expeditionary Sea Bases Could Become Drone Motherships

National Steel and Shipbuilding Company (NASSCO), a division of General Dynamics, has pitched some significant modifications to the U.S. Navy’s Expeditionary Sea Bases (ESB), which is an existing highly flexible class of ship based on a modified oil tanker that supports the forward deployment of various forces. The proposed enhancements were conceptualized to address evolving U.S. Navy requirements and include the notable addition of an unmanned underwater vehicle (UUV) bay.

First reported by Naval News in an article that’s very much worth its own read, NASSCO initially debuted the modifications during the Sea Air Space Symposium in 2022. However, the company once again highlighted them at this year’s Surface Navy Association National Symposium, at which Naval News was in attendance and spoke directly to NASSCO about these developments. Along with the introduction of this new UUV launch-and-recovery system (LARS), the company is also proposing an aft flight deck to support unmanned aerial vehicle (UAV) operations specifically and an unrelated ability to accommodate F-35Bs under certain scenarios.

Expeditionary sea bases USS Hershel “Woody” Williams (ESB 4) and USS Lewis B. Puller (ESB 3) sail together in the Gulf of Aden. Credit: U.S. Army Photo by Spc. Frederick Poirier

The Navy’s operational fleet of Lewis. B. Puller-class ESBs is currently made up of four commissioned ships: USS Lewis B. Puller (ESB 3), USS Hershel “Woody” Williams (ESB 4), USNS Miguel Keith (ESB 5), and USS John L. Canley (ESB 6). The family will eventually grow to six ships, as NASSCO was awarded a contract to build the future unnamed ESB 8 last August and began laying the keel for what will be the follow-on USS Robert E. Simanek (ESB 7) two months later

Special Operations Forces (SOF) and Airborne Mine Counter Measures (AMCM) are among the primary missions that these ships are optimized to support. The entire class is based on the giant Alaska-class oil tanker, a commercial design, which NASSCO believes will be a key factor in facilitating these potential upgrades to best meet the Navy’s needs. These ships have tremendous volume, deck area, and room for growth, and are remarkably inexpensive compared to ‘keel-up’ warship designs. Each one costs very roughly a similar sum as a single Littoral Combat Ship, or around $500 million.

USS Hershel ‘Woody’ Williams (ESB 4) is at anchor in the Chesapeake Bay, Sept. 15, 2019 during mine countermeasure equipment testing. Credit: U.S. Navy photo by Bill Mesta

Jim Strock, an independent consultant working with NASSCO on the ESB, told Naval News that in conceptualizing these modifications the company considered both existing Navy requirements and those that are emerging. He told the outlet that NASSCO looked at “Expeditionary Advanced Base Operations, Distributed Maritime Operations, and Littoral Operations in a contested environment” to inform the proposed upgrades, but the full background can be read in detail here.

As it stands, the Navy’s ESBs are designed around four core capabilities that the service identifies as aviation facilities, berthing, equipment staging support, and command and control assets. The huge vessels — which include a four-spot flight deck, mission deck, and hangar — measure 785 feet in length with a 164-foot beam and have a displacement of about 90,000 tons when fully loaded. 

While the ESB fleet is already used to support various smaller UUVs, as well as UAVs, and unmanned surface vessels (USV) in a limited capacity, NASSCO’s new potential modifications would significantly expand upon those existing capabilities. The UUV bay, for instance, seems to be especially centered around launching and recovering more sizable types, like the Boeing-built Orca drone submarine, and Strock revealed to Naval News that the company is calling this device the Rotary UUV Launch And Recovery System (RULARS).

Figuring out how to launch, recover, and forward deploy larger UUVs especially has been a challenge for the Navy since the use of unmanned technologies at sea began to accelerate. To address this, NASSCO’s concept rendering of RULARS shows that the system would be located deep inside the ESB’s hull and utilize a rotating drum-style system to more efficiently recover and launch the vessels.

A rendering of NASSCO’s UUV launch-and-recovery system concept for ESBs. Credit: General Dynamics NASSCO

RULARS would essentially serve the same purpose as the more traditional ‘moon pool,’ like the one famously used on the Glomar Explorer, which launches and recovers equipment through an opening in the bottom of the ship’s hull. However, this method poses stability concerns for ships at sea, especially when operating in rough waters.

RULARS seems intended to potentially mitigate those challenges by creating a more enclosed and controlled system for deploying the UUVs while retaining the moon pool. As the rendering shows, a UUV would be loaded into the rotating drum that’s submerged in the moon pool, the drum would close and spin while keeping the UUV upright, and then RULARS would release the vessel into the water, with the inverse of that process occurring for recovery operations.

Using a hull-mounted rotary launcher or a traditional moon pool also provides the ability to clandestinely launch and recover sight-sensitive UUVs outside of the gaze of prying eyes.

The Lewis. B. Puller class’ existing command and control architecture also makes it so the fleet is already well positioned for expanded unmanned operations. Strock told Naval News that the ESBs have “nearly 40 seats for operational planners,” and with command and control being one of the four core capabilities that the Navy wants ESBs to offer, it isn’t difficult to see how the fleet’s current facilities could ultimately be used to oversee unmanned activities.

Also contributing to NASSCO’s vision of turning these ESBs into drone motherships is the company’s proposed aft flight deck modification intended for UAVs. In a video interview with Naval News recorded during last year’s Sea Air Space show, Brett Hershman, director of business development for General Dynamics, explained that the aft flight deck would allow the ESBs to carry out their primary mission on their main flight deck — the third largest in the Navy — while creating a dedicated space for uninterrupted UAV operations at the same time. 

A rendering of NASSCO’s proposed aft flight deck modification for ESBs. Credit: General Dynamics NASSCO

USS Lewis B. Puller could especially benefit from these upgrades as the ESB is currently forward deployed to the U.S. Fifth Fleet area of operations in the Middle East and East Africa. The Navy is focusing on leveraging unmanned systems to maintain vigilance and enhance its operational capabilities in this troubled region above pretty much any other at this time. The Navy has stood up its unmanned and artificial intelligence innovation unit Task Force 59 here to execute trailblazing experiments with a highly diverse and evolving cast of unmanned systems. An ESB modified for enhanced unmanned mothership operations could be a great fit for new operational unmanned capabilities and experimental ones, as well.

The vessels that could be most logical for receiving some of these modifications are the forthcoming ESBs 7 and 8. With construction on ESB 7 not projected to wrap until sometime in 2027 and ESB 8 essentially being a blank slate until the keel is laid, both the Navy and NASSCO will have the opportunity to work together and decide how these ships could leverage the suggested modifications to best suit the Navy’s unmanned framework. These vessels were also built to be easy to modify, so some of the proposed features could be back-fitted to the existing fleet as time goes on. According to Hershman, these deliberations are ongoing.

The potential for these ESBs to carry F-35Bs under NASSCO’s proposed additions, however, was not touched on by Hershman in the Sea Air Space 2022 interview and appears to be more nuanced than the drone mothership concept. At present, potential modifications to the ESB’s flight deck to accommodate F-35Bs would mainly be used to facilitate transporting them long distances as opposed to launching regular sorties, but the latter could be possible under specific conditions.

Strock was blunt in his assertion to Naval News that the ESBs are not designed to operate F-35s, but rather that the modifications could eventually see the ships transiting F-35 airframes into theater. This could also mean that ESBs would be able to transfer the fighter jets to amphibious ships and aircraft carriers albeit with some alterations to the flight deck.

The F-35B ESB modification concept. Credit: Naval News scanned the photo from a General Dynamics NASSCO brochure

Still, one could see lightly configured F-35Bs, such as ones set up for counter-air duties, takeoff and immediately refuel from an MV-22 based aboard the same ESB, and continue on its mission, potentially recovering at another locale, for instance. Then again, just having MV-22s that are capable of refueling F-35Bs on the ESB could be beneficial for operations across the expansive Pacific theater, for instance.

What these modifications emphasize is how ESBs are essentially relatively inexpensive real estate the Navy can park anywhere in the world and adapt for a multitude of tasks. There is no doubt that the tapping of their potential is only just beginning, and becoming motherships for unmanned systems certainly makes sense and would fit with changing tactics based on these emerging capabilities.

Regardless, the ESB fleet’s ability to provide a persistent presence where the Navy needs it reflects value and relevance as threats grow in troubled regions. With this in mind, giving them an even larger unmanned support mission seems inevitable. 

Author’s note: This article has been modified to more clearly cite the information included that has been gathered from Naval News’ initial reporting on the proposed modifications.

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