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Combat Logistics Force

The idea of taking supplies to ships at sea and handling them across the water was new to the Navy at the turn of the century. Sailing ships had been able to stay where the action was for weeks or months; sea breezes provided the power, Sailor's diets were less complex, and round shot was more easily stocked than bombs and missiles.

Then came the day of the steamship with its huge appetite for coal. The large men-of-war burned 50 tons of coal a day, and to keep their bunkers full, had to return to port every 10 days or so to re-coal. The Navy learned a lesson in 1898 during the Spanish-American War. The Spanish Fleet was blockaded in the Harbor of Santiago, Cuba. When the Spanish made a run for the open sea, three of our ships (including the old battleship MASSACHUSETTS) were 45 miles away being re-coaled at Guantanamo. The need for on-station at-sea refueling was obvious. Early efforts to solve the problem led to the development of a high-line for carrying bags of coal from a coaler to a warship, one in the wake of the other.

World War One saw the beginning of the Navy's conversion to oil- burning ships, and soon the coalers were out of business."

It took the pressure of the Second World War in the Pacific, which reached into the far corners of that ocean, to make Underway Replenishment (UNREP) a regular feature of Naval Operations. The war in the Pacific made new demands on the Navy -- supply lines had to be extended, quickly, in order to project power across the oceans and keep it there.

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:

The Navy operates a Combat Logistics Force fleet of about 40 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:

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.

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Maintained by Robert Sherman
Originally created by John Pike
Updated Wednesday, December 09, 1998 2:37:12 PM