Expeditionary Support Ship (ESS) / Sea Force

As of 2002 the Navy was considering an Expeditionary Support Ship to provide the Marine Corps more amphibious lift, while serving as staging bases for special forces and perform command and control for mine countermeasures and other missions. Such ships could supplement the Marine Corps amphibious lift capabilities, boosting the assault assets traveling with forward deployed naval forces. Proposals under consideration were buying a few support ships, designed as variants of the yet-to-be-developed MPF(F) ships. The support ships could be optimized for different missions, including use as an afloat forward staging base for special operations missions, and mine countermeasures command and control missions, carrying helicopters once based on the Inchon (MCS-12). The ships could also carry an enhanced medical field capability.

The need for effective operation from the sea while conducting amphibious operations ashore has never been more evident than in today's modern conflicts. As important as this task is it has not significantly changed since World War I. Sea Force is an attempt to show that sea basing, as discussed by the Chief of Naval Operations (CNO) in Sea Power 21, can be accomplished by the year 2020 with reasonable advances in technology. The concept of sea basing implies a number of capabilities that are not inherent in current expeditionary forces, among these are Ship to Objective Maneuver (STOM), indefinite sustainment, selective offload, reconstitution of forces ashore, long range Naval Surface Fire Support (NSFS), and an increased capability in command and control. The Marine Corps has also established the requirement of a 3.0 Marine Expeditionary Brigade (MEB) lift capability that is not currently met by the existing force structure.

In 2002 the Total Ship Systems Engineering Program at the Naval PostGraduate School undertook the task of designing a system of ships that could be brought together to enable the sea basing of one MEB for an indefinite period of time. The Sea Force design completely supports all of the operational requirements of STOM in addition to providing a path for re-supply and a method for reconstitution of forces ashore. Sea Force also is designed to be reconfigurable from a warship to a supply ship during a shipyard availability period with minimal effort through the use of modularity. The first design analysis was based on combining the capabilities of the MPF, LMSR, and LHA ships into a single hull one-ship-does-all concept. The second design analysis was based on an MPF/LMSR variant with a separate LHA design. The third design analysis, the LHA/MPF with LMSR design, combines two ships on similar hull forms but with different structural requirements, layouts, and missions.

The summary report on the LHA(R) analysis of alternatives defined the Expeditionary Support Ship (ESS) including the ability to assemble in the open ocean and offload to amphibious ships and to the shore. It would provide multiple MV-22/CH-53 operating spots and LCAC interface (a well deck, or some type of side discharge facility, or other arrangement that is workable up to Sea State 3, as well as the capacity to store a substantial amount of vehicles and cargo and to conduct selective offload. The design would have enhanced survivability compared to a commercial ship or LMSR (but less than a combatant) - and all at a cost that is affordable.

Three proposed ship types: LHA(R), MPF(F), and a Large Medium-Speed Roll-on/Roll-off (LMSR) ship could be used to fulfill the role of an expeditionary support ship. A review of the literature of these three ship concepts provided details on the types of capabilities these platforms could be expected to provide. Documents included: "The Draft Amphibious Assault Ship, General Purpose (Replacement) LHA(R) CONOPS (Revision 5)" [7]; "The Maritime Prepositioning Force (Future) Draft CONOPS (1-03-02)"; and OPNAV Instruction 3501.199B (Required Operational Capabilities for the LMSR).

In the common platform design, all the ships would have exactly the same capabilities. In the variants design, a variety of hull versions would be built to host a smaller amount of related capabilities. For example, a ship of the sea base would be focused more on logistics capabilities, combat capabilities would be incorporated on another hull version.

A common platform design would be better able to operate independently because each ship would possess the required self-protection capabilities called for in the Master List of Required Capabilities. A common platform design could be more flexibly redeployed without having to take a number of ships with it to provide the required capabilities. Finally, the common platform family of ships would be inherently more survivable in that the required capabilities would be present on each platform and system redundancy would be optimized. A one-ship design is required to perform all missions of the three ship designs it is supposed to replace, combining the capabilities of the MPF, LMSR and LHA ships into a single hull one-ship-does-all concept.

The common platform design would have to be a large ship and therefore might cost more money to procure. Using one such ship to carry an MEU might yield a ship that could displace in excess of 110,000 LT, larger than any naval combatant ever constructed. A ship of that size raises all sorts of concerns. It would make more sense to use two ships per MEU, and 6 ships per MEB. Such a ship would have a length of 950 feet, a beam of 140 feet, and a draft of 40 feet, and displace 70,000 tons, incorporating a 30% growth margin. With this margin removed, the one-ship design might drop to around 48,000 LT.

The variant design would be able to optimize on certain capabilities and these more focused areas of responsibility might lead to a more effective employment of the required capabilities. The variant design would be less flexible in terms of employing platform elements independently. Some variants would have little to no self-protection capability. There would be limited redundancy; if one ship was damaged, the entire system might lose a significant portion of the capabilities associated with that particular platform.

An MPF/LMSR could function solely as the supply support vessel while the LHA would assume all of the combat roles. Each pair of ships could carry the equivalent of a Marine Expeditionary Unit (MEU). An LHA/MPF with LMSR alternative combines two ships on similar hull forms but different structural requirements, layouts, and missions. The division of resources is as follows: the LHA/MPF will have the bulk of troops, the combat systems, C4ISR, and ACE support. This will be more like a combat or command ship. The LMSR will carry fuel, provisions and ammunition, support a hospital and interface with commercial shipping.

Unlike MPF ships, which are forward deployed in three distinct squadrons, the support ships would sail with amphibious ready groups. The support ships would carry LCACs and LCUs, filling what the Marine Corps sees as a gap in its amphibious lift capabilities created by the inability to afford buying more amphibious ships. One NAVSEA estimate said making a prototype from an LMSR could take 22 months and cost $216 million, while less capable prototypes could be developed for somewhat less money and in less time.

This Expeditionary Support Ship (ESS) construct fell out of consideration by the year 2003.