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Expeditionary Sea Base (ESB)

Last updated: 21 Jan 2021


The Expeditionary Sea Base (ESB) ship class is highly flexible that may be used across a broad range of military operations supporting multiple operational phases, similar to the Expeditionary Transfer Dock (ESD) class. Acting as a mobile sea base, they are part of the critical access infrastructure that supports the deployment of forces and supplies to provide prepositioned equipment and sustainment with flexible distribution.

The ships were originally called the Mobile Landing Platform (MLP) and the MLP Afloat Forward Staging Base (AFSB), respectively. In September 2015, the Secretary of the Navy re-designated these hulls to conform to traditional three-letter ship designations. The design of these ships is based on the Alaska class crude oil carrier, which was built by General Dynamics National Steel and Shipbuilding Company (NASSCO). Leveraging commercial designs ensures design stability and lower development costs.

The USS Lewis B. Puller (ESB 3), USS Hershel “Woody” Williams (ESB 4), and follow on ships USNS Miguel Keith (ESB 5), John L. Canley (ESB 6), and Robert E. Simanek (ESB 7) are optimized to support a variety of maritime based missions, including Special Operations Forces (SOF) and Airborne Mine Counter Measures (AMCM). The ESBs, which include a four spot flight deck, mission deck and hangar, are designed around four core capabilities: aviation facilities, berthing, equipment staging support, and command and control assets. 

In August 2017, upon arrival in the U.S. 5th Fleet Area of Responsibility, ESB 3 was re-designated from USNS and commissioned as a USS. As a commissioned Navy ship, USS Lewis B. Puller (ESB 3) is commanded by a Navy O-6 with a permanently embarked military crew. This re-designation provides combatant commanders greater operational flexibility as to how the platform is employed in accordance with the laws of armed conflict.



The Navy awarded NASSCO a fixed-price incentive fee type contract for the detail design and construction of T-ESD 1 and T-ESD 2 in May 2011. A detail design and construction (DD&C) contract was awarded to NASSCO for T-ESD 3 in February 2012. The ship configuration was subsequently changed to ESB 3 mid-construction via an engineering change proposal in March 2014 after receiving JROC approval. A DD&C contract for ESB 4 was awarded on Dec. 19, 2014 and the construction contract for ESB 5 was awarded December 2016, and in August 2019, NASSCO was awarded the DD&C contract for ESB 6 and 7. T-ESD 1, T-ESD 2, ESB 3, ESB 4, and ESB 5 have delivered; in June 2020, ESB 6 began construction. 

General Characteristics, Expeditionary Sea Base (ESB)
Builder: NASSCO
Propulsion: Commercial Diesel Electric Propulsion
Length: 239.3 Meters (785 feet)
Beam: 50 Meters (164 feet)
Displacement: 90,000 tons (fully loaded)
Draft: 10.5 Meters (fully loaded); 12 Meters (load line)
Speed: 15 knots
Range: 9,500 nautical miles
Crew: 44 Military Sealift Command personnel
Military Crew: 101 military (Accommodations for 250)
USS Lewis B. Puller (ESB 3), Norfolk, Virginia
USS Hershel 'Woody' Williams (ESB 4), Souda Bay, Greece
USS Miguel Keith (ESB 5), San Diego, CA
John L. Canley (ESB 6) - Delivered

Robert E. Simanek (ESB 7) – Under construction

Point of Contact
Naval Sea Systems Command
Office of Corporate Communication (SEA 00D)

Washington, D.C. 20376

(202) 781-4123


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