T-ESB: Characteristics and Mission

Military Sealift Command operates the Lewis B. Puller class Expeditionary Sea Base (ESB) as a hybrid ship. While MSC operates the ship and is responsible for the physical ship, there will also be uniformed military personnel on board conducting operations. The exact makeup up the ESB crew will depend on the specific mission and current tasking.

ESBs are one of the larger vessels in the MSC fleet, and they have a unique and distinctive shape. ESBs are very tall and have almost 100 feet of freeboard from the mission deck to the flight deck. The Lewis B. Puller class Expeditionary Sea Base (ESB) was originally supposed to be designated as USNS Vessel; however, after they were introduced, they were changed to a USS designation. The distinction between USNS and USS is important. USNS stands for United States Naval Ship which designated that the ship is used for non-combatant operations and operated by civilians. 

Most MSC vessels are designated USNS. On the other hand, USS stands for United States Ship. USS Ships are used for combatant operations and directly owned and operated by the United States Navy. This directly relates to the vessels ability to launch offensive operations. Since ESBs are designated as USS, they are able to launch offensive operations.

Due to their hybrid makeup, ESBs will be different than typical USNS MSC ships. In addition to a licensed MSC Captain, there will also be a Military Chain of Command to include a Navy Commanding Officer (CO). The Navy CO will have a lot of power over the vessel and can play a big role in the morale of the crew. On board, there is a delicate leadership balance between the licensed MSC Captain and the Navy Commanding Officer. This balance will have a direct impact on the morale of the crew.

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

MSC Full Manning: 40-45 CIVMARs
Military: 120-200 mission depending.

Designed as a special mission’s ship, ESBs have a variety of military personnel on board to include Special Operations Forces, pilots and other entities. The operations they conduct will be dependent on the military forces they have on board. The ESB is supposed to act as a flexible base of operation to launch a variety of mission. This is why the designation of USS vs USNS is so important. As a sea base, ESBs conduct a lot of flight and small boat operations. The ESB flight deck has 4 landing spots and can fit multiple helicopters inside its hangar. ESBs also have davits capable of launching small boats.