High-End Warfare Requires Changes to the Combat Logistics Force
Proceedings Magazine

High-End Warfare Requires Changes to the Combat Logistics Force

High-End Warfare Requires Changes to the Combat Logistics Force
Proceedings Magazine
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Present-day naval officers may be unaware that one of the Navy’s most famous sons is the father of modern underway replenishment (UnRep), Fleet Admiral Chester Nimitz.  As a young lieutenant serving as the chief engineer and executive officer of the Navy’s second oiler, USS Maumee (AO-2), Nimitz was tasked with devising a method of refueling destroyers while under way. In the past, refueling operations took place in the relative safety of a port or anchorage. With the start of World War I and the need to get destroyers across the Atlantic Ocean to bolster allied defenses against Germany, however, the Navy was forced to abandon stationary refueling practices and strike out on unchartered waters. At the time, destroyer fuel tanks were large enough to sustain a ship during patrols of a fixed location, but did not have the capacity to ensure continuous operations across wide expanses of ocean like the Atlantic. Aided by two other lieutenants and a chief boatswain’s mate, Nimitz devised a method of underway replenishment that involved towing the destroyers alongside the oiler using a large towing hawser and then shoring up the arrangement by passing breast lines.  The Maumee ’s booms, originally designed for use in-port, were then swung out to support the fuel hoses running between the two ships.  This arrangement, not unlike today’s modern UnRep methods, allowed the hoses to be kept out of the water while fuel was fed directly to a destroyer’s bunker tanks.  Nimitz’s pioneering ideas for UnRep set the Navy on the path of sending ships far beyond U.S. shores with little concern for the availability of fueling stops in route to the ultimate destination.

Having proven its worth in World War I, UnRep became a standard point of training for the Navy in the 1920s and 1930s.  Although not widely used at the beginning of hostilities, UnRep became what the now very much promoted Admiral Chester Nimitz termed “the Navy’s secret weapon” during World War II. With the expanse of the Pacific Ocean far greater than that of the Atlantic, UnRep became crucial to the success of the Navy and Marine Corps’ island-hopping campaign heading west. Never before in history had U.S. forces been so spread out across a single ocean.  With Sailors, Marines, and Soldiers fighting in almost every part of the Pacific, it was imperative that the “beans, bullets, and black oil,” so eloquently coined by World War II veteran Rear Admiral Worrell Reed Carter, needed for their success kept coming.  In 1945, Carrier Task Force 58 began attacking mainland Japan.  Comprised of more than 100 combatant ships, it took an underway replenishment group of nearly 40 ammunition ships, oilers, and stores ships to keep the carrier task force in the fight.  Although the underway replenishment group was capable of supporting the combatant vessels, replenishment operations demanded a complex scheme of maneuvers requiring the task force to make stops at all three single-product supply ships to receive all necessary goods. This made replenishment a lengthy affair, time that would have been better spent fighting the enemy.

In the Atlantic, the German Navy of World War II had a somewhat different idea regarding auxiliary ship design. The concept of a multi-product supply ship was developed by German naval engineers with the construction of the Dithmarschen in 1938 . As Thomas Wildenberg, a noted naval historian, writes, “Although she looked like a typical tanker, she was the first multi-purpose replenishment ship and had cargo spaces for refrigerated food, dry provisions, ammunition, and general supplies in addition to 67,000 barrels of fuel oil.” Although designed to replenish ships while breasted alongside in the safety of a port or anchorage and thus not an underway replenishment ship in the modern sense, construction of theDithmarschen proved that a single ship could carry and deliver all the goods needed to sustain warships from the sea. At the end of the war, Dithmarschen was granted to the United States as part of war reparations and commissioned USS Conecuh (AOR-110). The Conecuh proved her worth during Sixth Fleet operations in the spring of 1954, replenishing 87 ships with fuel and stores.  It was the performance of the Conecuh coupled with the ever growing and insatiable needs of the aircraft carrier that led then-Chief of Naval Operations (CNO) Admiral Arleigh Burke to initiate the design of a whole new class of underway replenishment ship—the fast combatant support ship (T-AOE). Admiral Burke had been part of Task Force 58 during the 1945 strikes against Japan commenting:

We fought nearly every day and we used lots of fuel, ammo, and all other expendable material, including food. All time spent in replenishing was time lost in combat.  Sometimes it was most important that the carriers being replenished should get back into their combat area as soon as they possibly could. This is when I had impressed on me the value of time. No fleet commander can ever tell what a few minutes might mean in the future. 1

Fast Combatant Support Ship

A fast combatant support ship is an auxiliary ship whose primary mission is logistics support of the carrier battle group. It is an integral part of the battle group and supplies the fuel, ammunition, and stores in a single combined replenishment, thus minimizing the highly vulnerable time combatants are connected to the replenishment ship. 2 Commissioned in 1964, the Navy’s first fast combatant support ship was USSSacramento (T-AOE-1).  With a length of 795 feet and a beam of 107 feet, Sacramento -class T-AOEs were capable of achieving 26 knots, allowing them to keep pace with carrier strike groups. In addition to the speed advantage never before achieved by an auxiliary vessel, the Sacramento -class T-AOEs had a fuel cargo capacity of 177,000 barrels, an ammunition stores capacity of 296,000 cubic feet, and a stores (dry and refrigerated) capacity of 105,000 cubic feet. T-AOEs first contributed to U.S. warfighting efforts in early 1965 during the Vietnam conflict and allowed U.S. combatant ships to receive all necessary goods from one ship vice three.

Four Sacramento -class T-AOEs were built ( Sacramento , Camden , Seattle , and Detroit ) serving successfully until the early 2000s. In the late 1980s, the Navy designed a new T-AOE known as the Supply(T-AOE-6) class.  The new T-AOE-6 fast combatant support ships were designed to meet the mission requirements of the Sacramento -class ships, but were built with one less cargo hold because of budgetary constraints. With a length of 754 feet and a beam of 107 feet, Supply -class ships were equipped with four gas turbine engines allowing the ships to travel at the high speed a carrier strike group. Four ships of the class were built in the 1990s ( Supply , Rainier , Arctic , and Bridge ). 

The Supply  and Arctic remain in active service.  By the 2030s, no T-AOEs will be supporting the U.S. Navy.  Rather, the Navy’s mid-21st century at-sea logistics needs will be supported by Henry J. Kaiser (T-AO-187)-class fleet replenishment oilers, Lewis and Clark (T-AKE-1)-class dry cargo/ammunition ships, and the future John Lewis (T-AO-205)-class fleet oilers. Although T-AOs and T-AKEs are capable ships, they are no substitute for the versatility of the T-AOEs. Admiral Burke, one of the Navy’s most battle-tested officers, demanded that carrier strike groups be supported by multi-product UnRep ships capable of traveling at the same speed as the group and providing for all of the group’s needs. The Navy certainly will benefit from the reduced costs of operating just two classes of auxiliary ships (TAOs and T-AKEs), but the Navy will be regressing in its UnRep capabilities by focusing on the design and acquisition of supply ships lacking the elements of the T-AOE.

The T-AO and T-AKE: Shuttle Ships Becoming Station Ships

Beginning in the early 1980s, the Navy began procuring Henry J. Kaiser -class fleet replenishment oilers. Fifteen of these ships entered service between 1986 and 1996. Capable of carrying 180,000 barrels of cargo fuel, the Henry J. Kaiser -class oilers can provide for the refueling needs of a carrier strike group. Their ability to carry and deliver solid cargo, however, is far less robust. The Henry J. Kaiser -class ships cannot carry any ammunition and the transportation of refrigerated cargo is limited to the use of several refrigerated shipping containers on deck. As for dry stores, there is minimal stowage capacity in a forward hold of 29,000 cubic feet.

The Lewis and Clark -class dry cargo/ammunition ships offer almost the exact opposite features of theHenry J. Kaiser fleet replenishment oilers.  Designed, acquired, and built in the early 21st century, the U.S. Navy now has 14 Lewis and Clark -class ships, 12 of which support the Combat Logistics Force needs of the various fleets. Another two support the U.S. Marine Corps Maritime Prepositioning Force in the Pacific Ocean. With a minimal fuel capacity of 25,600 barrels, the T-AKE-1 dry cargo/ammunition ships cannot satisfy the fuel requirements of an entire strike group. On the other hand, these ships do have a hardy stores and ammunition capacity of 5,298 short tons.

It is clear that the Henry J. Kaiser and Lewis and Clark -class vessels were designed to carry one commodity well—either fuel oil or solid cargo. On the other hand, T-AOE-6-class vessels were built to carry a mix of cargo to sustain a strike group. Under naval logistics doctrine, the Henry J. Kaiser -class fleet replenishment oilers and the Lewis and Clark -class dry cargo/ammunition ships were designed to be shuttle ships whose purpose is to bring the necessary goods to station ships through UnRep and consolidation operations (CONSOL).  CONSOL is the process by which a shuttle ship transfers cargo fuel to a station ship. Unlike UnReps between an oiler and a combatant, CONSOL allows fuel to be transferred from a shuttle ship’s cargo tanks to the cargo tanks of the station ship. This allows station ships like theSupply -class vessels to remain with a strike group at sea providing all the group’s supply needs. Today’s Navy, however, is slowly moving away from the shuttle/station ship concept. Ronald O’Rourke, a specialist in naval affairs for the Congressional Research Service, writes:

During the Cold War, the Navy procured underway replenishment ships to support a two-stage approach to underway replenishment in which single-product ‘shuttle’ ships (such as oilers, ammunition ships, and dry stores ships) would take their supplies from secure ports to the relatively safe mid-ocean areas, where they would then transfer them to multiproduct ‘station’ ships called TAOEs and TAORs.  The TAOEs and TAORs would then travel to Navy carrier strike groups operating in higher threat areas and transfer their combined supplies to the carrier strike group ships.

The Cold War has been over for more than two decades, and the Navy has relaxed its shuttle/station ship doctrine—going so far as to allow station ships to take their cargo all the way to a strike group.  This is the norm for present-day fleet logistics. Tensions demanding the attention of the Navy, however, are rising in the Far East.

Need for Multiproduct UnRep Ships

In their article, “Sea Strangulation: How the United States Has Become Vulnerable to Chinese Maritime Coercion,” Professor Patrick Bratton and Captain Carl Schuster, U.S. Navy (Retired), brought to light the actions of the People’s Republic of China in the South China Sea.  Claiming both the Paracel and Spratly Island Archipelagos, Bratton and Schuster write, “China has embarked on a large-scale construction program there, dredging entrances into the archipelago’s islets and atolls and destroying sensitive coral reefs to use as landfill for the building of airfields and military facilities.”  Channels leading to deep water lagoons and the numerous airfields recently constructed will most certainly be used to the benefit of Chinese ships and aircraft in the event of any military action in the South China Sea.  Based on the present-day militarization of the South China Sea and growing concerns for military threats in the East China Sea, naval logisticians must be prepared to serve the needs of carrier strike groups over distances not experienced by the Navy since World War II.


Single product replenishment ships, currently represented by the Henry J. Kaiser -class oilers and Lewis and Clark -class dry cargo/ammunition ships, by themselves will be less efficient in meeting the Navy’s overall logistics needs of the future.  The shuttle ship design of these vessels make them perfect for delivering one specific product, but not all the material needs for sustained combat operations of a carrier strike group. Some may argue that the future John Lewis -class fleet oilers, formerly referred to as T-AO(X)s, are the answer, working with T-AKEs. This view is short-sighted, however, as the John Lewis -class fleet oiler is basically an upgraded Henry J. Kaiser -class oiler with slightly more solid cargo capacity, but still lacking the ability to transport ammunition and the needed speed to maintain station with a carrier strike group.

What the Navy needs is a next generation T-AOE.  As shown in World War II, time spent replenishing is time lost fighting. Aircraft carriers and their escort ships need to get alongside auxiliary ships and replenish their stocks quickly so as not to give the enemy the upper hand. Having to replenish alongside two separate auxiliary ships, a T-AO and a T-AKE, in a future battle scenario leaves the combatant and auxiliary ship vulnerable to attack. 

In the event of conflict in the South or East China seas, the shuttle/station ship logistics model will be of utmost importance. If unable able to access the continent of Asia, T-AOs and T-AKEs may need to bring cargos across the Pacific from Hawaii or the U.S. West Coast as part of a great supply chain. The Navy’s T-AOs and T-AKEs will then need to CONSOL with several T-AOEs, which in turn will resupply carrier strike groups operating forward. Unfortunately, the number of T-AOE’s in the Navy count today—and as planned for the future—will not suffice in a major showdown.  Now is the time to reevaluate future logistic needs and the capabilities of the ships that will provide for those needs.

1. M.O. Miller, J.W. Hammet, and T.P. Murphy, “The Development of the U.S. Navy Underway Replenishment Fleet,” SNAME Transactions, 95, 123-158.

2. P. Covich, “A Fast Combatant Support Ship,” Naval Engineers Journal , vol. 97, no. 4, May 1985, 27-36..

Michael Fitzgerald is a veteran of the U.S. Navy having served on active duty on board USS Vicksburg(CG-69) and USS George H.W. Bush (CVN-77), as well as ashore at Military Sealift Command Headquarters.  He graduated from the U.S. Merchant Marine Academy in 2011, holds an Unlimited Third Assistant Engineer's License, and is now a federal employee at the Maritime Administration.

Brendan Pigott is a veteran of the U.S. Navy having served on active duty on board USS Chafee (DDG-90) and USS Kauffman (FFG-59), as well as ashore at Officer Training Command Newport (OTCN).  He graduated from the Massachusetts Maritime Academy in 2009, holds an Unlimited Second Mate's License, and is now a federal employee with the Military Sealift Command.

Authors’ Note: The authors wish to express their appreciation to Commander Mark Roemhildt, U.S. Navy, and Mr. Leonard Bell for their assistance with this article.

This article appeared originally at U.S. Naval Institute's Proceedings Magazine.

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