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Amphibious Cargo Beaching Lighter

The Higher Sea State Logistics Support for Expeditionary Forces ATD addressed the problem of transporting large quantities of bulk cargo and fuels from amphibious/sealift ships to the shore in support of landing forces. Its objective was to demonstrate an Amphibious Cargo Beaching Lighter (ACBL) for ship-to-shore cargo movement in higher sea states. Without adequate port facilities, power projection requires operational capability of Joint Logistics Over the Shore (JLOTS) operations in wind and wave conditions through sea state 3 (SS3).

The Amphibious Cargo Beaching (ACB) Lighter was a prototype modular barge system which was evaluated to replace the Navy Lighter (NL) pontoon causeway system. The ACB Lighter was to be rapidly deployed from an auxiliary crane ship and be assembled and operated in sea conditions through sea state three to support Joint Logistics Over the Shore (JLOTS) operations.

In a Joint Logistics Over the Shore (JLOTS) operation, throughput ceases in sea state three (SS3) conditions.In response to these issues, the Naval Facilities Engineering Service Center (NFESC), under funding from the Office of Naval Research (ONR), began a research and development (R&D) program in Fiscal Year (FY) 1993 to review the technologies required for development of an advanced causeway system. The results of this effort identified a concept for an advanced modular causeway lighterage/platform system that promised significant advances in the LOTS/JLOTS operation. This system would break the SS2 operation barrier. In addition, the system will be readily deployable from available lift assets.

Because an extensive market survey did not reveal any commercial source for either of these technologies, a development program was begun by the Navy under funding from the Office of Naval Research (ONR). Via this program NFESC successfully developed concepts for both rigid and flexible SS3 connectors. It became clear that an open-sea connection system would be required to assemble platforms in theater. This system would need both rigid (module to module, e.g., for assembly of a causeway section) and flexible (section to section, e.g., for assembly of a causeway ferry) connectors.

The Phase I effort culminated in the preliminary structural design of 24-ft wide monocoque ACB Lighter modules. The objectives of this Phase II study were: (1) develop structural design guidelines which can be used to design a lightweight module structure; (2) account for structure required to mount flexible and rigid connector assemblies and its impact on hull weight; (3) revise preliminary design to reflect modified design criteria; and (4) if final design resulted in a module which exceeded the 30-long ton design goal, assess impact on handling, stacking and transporting.

Technology issues were quickly resolved in the development of this modular system, which promised ease of transport, increased payload capacity and the ability to safely operate in SS3; however, it became clear that an open-sea connection system would be required to assemble platforms in theater. This system would need both rigid (module to module, e.g., for assembly of a causeway section) and flexible (section to section, e.g., for assembly of a causeway ferry) connectors. Because an extensive market survey did not reveal any commercial source for either of these technologies, a development program was begun by the Navy under funding from the Office of Naval Research (ONR).

The concept system, the Amphibious Cargo Beaching Lighter (ACBL, a.k.a. ACB Lighter), used an innovative module design and advanced connector technologies to makes assembly and operation in SS3 achievable. The ACB Lighter modules, at 40 feet long, 24 feet wide and 8 feet high, had several advantages. They are easy to transport by sea and over land. For overland transport, the module is separated into three 8-foot-wide intermodal assemblies. Aboard ship, the 24-foot-wide module either spans adjacent ISO container cells in the ship's hold (similar to the Navy Seashed) or is deck-loaded.

The platforms are quick to assemble, fewer are needed in theater and the various sizes and configurations meet changing needs at a forward logistics site. The platforms can include warping tugs, single- and double-wide causeway ferries, roll-on/roll-off platforms, air cushion vehicle landing platforms, causeway piers, and air cushioned transport platforms.

To assemble the platforms in theater, the ACB Lighter requires an at-sea connection system. During in-water assembly, significant relative motions are experienced between the adjoining ends of modules. A bridle system has been designed to overcome these motions and assist the alignment of modules for connection. A rigid pin and guillotine connector is used in the module-to-module configuration, and a flexible connector is used to link larger assemblies, such as causeway ferries.

Assembled causeway lighters and platforms provide better stability and greater payload capacity due to the extra freeboard and width of the modules in contrast to present-day capabilities. The cargo capacity of an ACB Lighter causeway section is three times greater than that of the existing system; thus, cargo throughput is increased. An even greater payoff is the capability to operate safely in SS3 conditions.

NFESC's R&D efforts for the ACB Lighter concept included extensive model testing of the modules and the connection system. One-quarter scale testing of a module connection system has been conducted in a wave basin as well as at-sea. An alternative module connector was evaluated using simulation modeling. The flexible connection system was tested at three-quarter scale aboard NL causeway assets. The feasibility of manufacturing the modules out of composite materials has been investigated by the Naval Surface Warfare Center, Carderock Division (NSWC-CD). NSWC-CD also investigated the feasibility of using air-cushioned landing craft to support the LOTS operation.

The most significant effort in the ACB Lighter R&D program was a full-scale demonstration in the summer of 1998 of the intermodal module configuration and the SS3-capable connection system. A major full-scale realistic demonstration by the Navy amphibious elements in the open ocean waters off the coast of Virginia in 1998 confirmed the ability to assemble the modules into various plat form configurations. The platforms are quick to assemble, fewer are needed in theater, and the various sizes and configurations meet changing needs at a forward logistics site.

With ACTD completed in 1999, and with the feasibility of a SS3-capable causeway system established, the services decided to pursue acquisition of a Joint Modular Lighter System (JMLS).



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Page last modified: 07-07-2011 12:37:20 ZULU