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Combat Logistics Force

Without the ability to do underway replenishment, the US would not be able to maintain presence forward for months on end on a continuous basis. Underway replenishment is something that the United States Navy does better than anybody and always has done better than anybody. And it is the key component that keeps ships in the Mediterranean, in the Indian Ocean, in the Persian Gulf without having to go back to port on a very regular basis.

To accomplish effective support at sea, the Navy establishes hubs afloat. These hubs carry or receive PMC for transfer to other ships at sea. Replenishment at sea, primarily through UNREP, is done by moving materiel across rigging between two ships (CONREP) or by military or commercial helicopter (VERTREP). The primary hub for UNREP is the CLF ship. These ships are configured and equipped for cargo transfer to other ships underway. Other military or commercial vessels can be pressed into service by embarking cargo afloat rig teams (CARTs) to provide and operate temporary rigging for limited ship-to-ship transfers. Primary CLF ships involved in UNREP of supplies today are the T-AFS, T-AO, T-AE, and the AOE. CLF hub ships primarily receive materiel in port at the FLS, ALSS, or other supply point.

The T-AFS is stocked to a specific plan-called a fleet issue load list (FILL)-for issue to requisitioning ships. In addition, the CLF ship will pick up freight for ships it will be replenishing. Dependent on operations, materiel availability, and logistics replenishment (LOGREP) schedules, Naval Theater Distribution, the T-AFS may also receive materiel from other CLF ships at sea. T-AOs and AOEs load petroleum products at defense energy supply points (DESPs) at the FLS, ALSS, or other locations in or near the theater. T-AOs and AOEs at sea also receive transfers from other oilers and point to point tankers; this is termed consolidation (CONSOL). T-AOs and AOEs also load ordnance at in theater U.S. ordnance facilities.

Logistics support is a basic need of any fighting force, and it must be maintained and modernized to remain viable. For naval forces, logistical support requires a capability to re-supply at sea by means of replenishment ships. Some Combat Logistics Force (CLF) ships (station ships) are integral parts of the surface battle groups and others (shuttle ships) move logistical supplies from ports, forward logistics sites, or commercial ships (black hulls) to the battle group at sea. For instance, T-AKE Lewis and Clark [former T-ADC(X)] will be primarily a shuttle ship, providing logistics lift from sources of supply to station ships and other ships operating with naval forces. Additionally, T-AKE may be required to operate in company with a T-AO 187 Class ship while performing a station ship role.

The Auxiliary Cargo and Ammunition Ship (T-AKE) program will provide a two product (ammunition and combat stores - including dry stores, frozen and chilled products, spare parts and consumables) shuttle ship replacement for the aging Combat Stores (T-AFS-1/ 8 classes) and Ammunition (T-AE-26 class) shuttle ships. The T-AKE will also have a limited combatant refueling capability. In its shuttle role, the T-AKE will provide logistics lift to station ships from supply sources, such as friendly ports, and at sea from Modular Cargo Delivery System (MCDS) equipped merchant vessels. Working in concert with an Oiler (T-AO), the pair can perform a "substitute" station ship mission providing provisions; spare parts, dry stores, ammunition and fuel directly to naval combatants in the absence of an assigned AOE station ship. This will replace the current capability of the AOE-1 Class Fast Combat Support Ship.

The support of ships at sea is complicated by specific environmental (wind/sea state) impediments to resupply, and broader threat spectrums (including subsurface as well as surface and air). The US Navy excels at underway replenishment (UNREP), but weather, threat, or operating conditions can render UNREP impossible at times. Planners seek to prevent support shortfalls by ensuring necessary support in spite of natural or enemy action.

Underway Replenishment is the method by which provisions, ammunition and fuel are transferred from one ship to another at sea. The technique of replenishment at sea enables a fleet or naval formation to remain at sea for prolonged periods of time. There are two methods by which UNREP is accomplished:

(CONREP) - Connected Replenishment is a way for Ships to replenish other Ships at sea of needed Supplies. This involves rigging a cable to the ship they are supplying and sending supplies over a ram-tensioned Wire system known as Standard Tensioned Replenishment Alongside Method (STREAM) using a system of pulleys to travel the Wire. In this method, the ship maintains a steady course and speed, while the receiving ship comes alongside at 80-200 feet. The replenishment ship can service two ships at a time, one on either side. Depending on the material to be transferred, the ships are connected together with wires which run through UNREP rigs where fuel hoses or trolley devices are passed. When fueling, the hoses are hooked up and fuel is pumped to the receiving ship. When transferring supplies, they are palletized and sent over to the receiving ship. The trolley is then returned to the replenishment ship for another load.

(VERTREP) - Vertical Replenishment is another way for ships to replenish Ships at sea of needed supplies often Replenishment ships will use this and (CONREP) at the same time to speed up the process. This method utilizes helicopters to transfer prepositioned palletized supplies from the flight deck of the replenishment ship to the flight deck of the receiving ship. The helicopter then hoists up the pallet (which has been placed in a cargo net), and flies it over to the receiving ship where it is lowered onto their flight deck.

Strike-up is the process of locating the required material in its stowage location, decomposing from the shipping configuration (when/where necessary), configuring the material for consumption/shipping, and moving the material to the shipboard location where it will be consumed, used, or transferred off the ship. Strike-down is the process of receiving material from a ship onload point (the CONREP or VERTREP station, wet well, or other loading point), decomposing from the shipping configuration (when/where necessary), moving the material to the designated stowage location, and securing the material.

The Navy operates a Combat Logistics Force fleet of ships that resupply combatant ships at sea with several commodities. The ships carry significant amounts of these commodities, for example, ship and aviation fuel (DFM and JP-5, respectively), ordnance, and other supplies such as ship and aircraft fuel, ordnance, and food, which enables combatant ships to operate at sea almost indefinitely, if required, without ever needing to go into ports to replenish their stocks. The force represents additional days of sustainability for the naval force by serving as an extension of the combatant ships' bunkers, magazine and store rooms.

            Capacities of Selected Combat Logistics
                          Force Ships
     Class             Speed     Fuel\ a    Ordnance    supplies
     ------------  ----------  ----------  ----------  ----------
                      (knots)   (barrels)      (tons)      (tons)
     (T-) AE-26            20          \b       6,000          \b
     (T-) AFS-1            20      18,000          \c       7,000
     AO-177                20     150,000         625         420
     (T-) AO-187           20     180,000          \c          \d
     AOE-1                 30     177,000       2,500         750
     AOE-6                 30     156,000       1,800         650
     Note:  T-class Combat Logistics Force ships are operated by the
     Navy's Military Sealift Command.  These ships use civilian, instead
     of military, crews but may have a small military detachment aboard. 
     A majority of the non-AOE class ships are now operated by the
     Military Sealift Command. 
     \a Reflects a combined total for DFM and JP-5. 
     \b Primary mission is ordnance replenishment.  Limited quantities of
     fuel and other supplies are also available. 
     \c No ordnance carried. 
     \d Primary mission is fuel replenishment.  Limited capacity to carry
     other supplies. 
                         Average Daily Fuel and Ordnance
                       Consumption Rates for Selected Ship
                                            DFM          JP-5      Ordnance
     Ship class                       (barrels)     (barrels)        (tons)
     ----------------------------  ------------  ------------  ------------
     Carrier (CV)                         2,700         6,500        70-150
     Carrier (CVN)                           \a         6,500        70-150
     CG-47                                  725            \a            \a
     DD-963                                 710            \a            \a
     DDG-51                                 710            \a            \a
     \a No quantities shown. 

Evaluated force levels for various scenarios show that station ships are required to maintain battle group endurance. The ability of the AOE's to provide all replenishment services simultaneously minimizes the non-operational time of the battle group. Alternatives which use multiple shuttle ships in combination to perform the station ship functions (such as AORs combined with AEs) require multiple replenishment which, coupled with their slower speed, reduces the on-station time of the battle group. These combinations are more expensive to operate and exacerbate the shortfall of AE ships.

The conventionally powered cruisers and destroyers that are a part of carrier battle groups are dependent on underway replenishment support by Combat Logistics Force. Compared to a conventional carrier, they have smaller fuel storage capacities and relatively high fuel consumption rates at higher speeds. Station ships travel with carrier battle groups. They carry petroleum products, ordnance, and other supplies and are generally replenished by shuttle ships operating from land-based facilities worldwide. The presence of a station ship in the battle group extends the group's range considerably.

There are several UNREP areas that are candidates for improvement. Selected areas for improvement, consideration and industry involvement are listed below:

  • Reduction in manning
  • Inventory management and planning aids
  • Computerized inventory tracking of cargo
  • Software planning aids for cargo stowage handling and transfer
  • Incorporation of commercial practices and new technology
  • Cargo handling systems
  • Commercial packaging systems
  • Means of stowing and handling solid waste
  • Flexibility to adapt to any cargo load
  • Flexibility to stow and handle various type of ammunition and ordnance
  • Improved operations in high sea conditions
  • Improved cargo strike up and strike down rates
  • Fiber optics for lighting and communications systems

The actual transfer of material from ship to ship is not the weak link in the replenishment chain. During actual UNREP operations, the ability of the receiving ship to strike down palletized material usually dictates the pace of the evolution. For the delivering ship improvements in strike up, pre-staging management of materials and inventory management are all needed.

In combat, frequent resupply every two or three days is a necessity. For example, a carrier battle group may use as much as 150 tons of ordnance and 30 tons of stores in one day when conducting surge operations. The emphasis in underway replenishment is on rapid transfer of materiel from the seabase or combat logistic ship to a combatant or carrier. Once that transfer occurs, however, the combatant too often is left with pallets or cargo nets of stores dumped on its decks. Moving the materiel below into storerooms where it can be properly identified and located may take days. Materiel is generally not available for use until this takes place. The strikedown and stowage process on board the combatant remains a challenge. The primary targets for these Strike-Up/Strike-Down technologies are Carriers, Future Maritime Prepositioning Force [MPF (F)], and this technology will also support the LHA(R) as well as expeditionary and future support ships and combatants.

Strike down is the process of moving material from the weather deck of a ship (the CONREP or VERTREP station, wet well, or other loading point) to the designated stowage location and securing the material. St rike up is the process of pulling the material out of stowage and moving it to a location where it will be used or transferred to another platform.

This problem requires three separate investments. The product line must address technologies that help move the cargo from the delivery point on the ship to the stowage area/magazine, technologies that stow cargo loads, and selective offload technologies to automate cargo holds/magazines and allow an individual load to be called up from storage.

Currently, many combatant vessels perform strike up and strike down using large work parties. Much of the material must be broken out of pallets and containers into packages that can be manhandled through the ship . It is a workload intensive operation and presents many opport unities for injury. When the materials reach the designated stowage space, they must be repackaged and secured. This is a highly inefficient way to perform these functions and causes substantial disruption in the ship operations. As a result, the ability of the ship to perform its military mission is impacted for many hours after completion of an underway replenishment.

The 2001 CVN Operation Advisory Group (OAG) states that procedures for moving material throughout the carrier are manpower intensive, time-consuming and inefficient and recommends the development robotic handling equipment to move material. It also states that current weapons strike-up capacity does not meet planned sortie generation rate requirements for sustained, high tempo operations. A recommendation is to fund new initiatives with potential for backfit to improve weapons through-put.

The Heavy Unrep transfer system will double both the maximum capacity and throughput rate of today's system. Additionally, this product line seeks to reduce Unrep manpower requirements by 40%, and increase ship separation for greater safety. The primary technology emphasis of this product line are relative motion compensation, transfer motion control, advanced materials, and ship positioning. The primary transition paths for this technology are the MPF(F) as a means of linking the Combat Logistics Force and the family of Amphibious Ships, and the T-AKE dry cargo replenishment ships.

Specific aspects of underway replenishment present tremendous challenges. One such area is the process of skin-to-skin replenishment. This is a separate and distinct category of replenishment that is conducted by transferring material from two ships located directly next to each other, whether at anchor or moving at slow speeds. This method of replenishment would be the first alternative in transferring 20 foot ISO containers from commercial or strategic sealift ships directly to the combat logistics force and seabase due to the shorter duration of the transfer operation as well as the reduction of inherent safety risks. Skin to skin replenishment is extremely difficult under all but the calmest conditions due to the forces of water acting between the vessels, and the danger of the vessels colliding even while not making way. While skin-to-skin replenishment is not possible under all conditions and with all situations, increased capabilities for situations with higher sea states are desired. Potential technology investment areas include evaluations into advanced fendering or mooring techniques and approaches, advances in ship heading control systems and further crane developments or alternative crane concepts.

Skin-to-Skin replenishment has been extremely difficult under all but the calmest conditions because it is often conducted at anchor and the roll motion of the ship is significant. A Sea State 3 crane ATD is on-going that will enable a crane to cancel out the load pendulation due to this roll in up to Sea State 3. This is a very significant improvement, but will be inadequate to provide a robust and reliable sustainment capability in the open ocean environment of Sea Basing. This product line will enable the operation to be done while underway at steerage speed so that a heading can be chosen to minimize roll. As its goal, it will improve the crane technology to enable Sea State 5 operations and it will provide the technologies for fendering and securing that will provide the Commanding Officers / Ships Masters with the confidence they need to conduct the operation. While skin-to-skin replenishment is not possible under all conditions and with all situations, the product line seeks to develop capabilities for employing skin-to-skin transfer in higher sea states.

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Page last modified: 07-07-2011 12:48:37 ZULU