Naval History and Heritage Command

Naval History and Heritage Command

A Century of Replenishment at Sea

Commander John A. Lukacs IV, USN


Reprinted from Naval History with permission; Copyright © (2018) U.S. Naval Institute /


"Underway replenishment was the U.S. Navy’s secret weapon of World War II." — Fleet Admiral Chester Nimitz, U.S. Navy 

Since its earliest days, the U.S. Navy has patrolled waters far from home, often without access to friendly ports of call in which to replenish ships. Though this never has been a problem unique to U.S. ships, it appears the U.S. Navy was the first to solve it. The first documented replenishment of a warship at sea was conducted by the USS Constitution in the Caribbean Sea during the 1799 Quasi-War. The Constitution was replenished by small boats, with supplies lowered in barrels from one ship, rowed across, and then hoisted on board the U.S. frigate, a method that kept her on station for almost an entire year.

But it was not until the years following the 1898 Spanish-American War — during which the inability to resupply coal at sea led to one of four battleships missing a major action — that the Navy began to develop systematic at-sea replenishment. The most successful idea used equipment exclusively located on colliers to transfer bags of coal, though it quickly became obsolete with the Navy’s shift to oil-burning engines. These early efforts nevertheless provided important foundations for subsequent systems.

World War I and the Interwar Years

The modern story of operational underway replenishment (UnRep) — of a type that would be recognizable by present-day sailors — begins in late 1916 at Guacalabya Bay, Cuba, on board the USS Maumee (Fuel Ship No. 14), the first diesel-powered U.S. Navy surface ship. The officers of the Maumee knew that the United States would enter World War I and that the then-current method of replenishment — while ships were moored together in a protected harbor — would be unavailable to short-legged destroyers during a transit across the Atlantic Ocean. (The older Paulding-class destroyers, at only 742 tons, did not have the range of the newer 1,000-ton destroyers.) They might have had knowledge of a 1913 experiment involving the USS Arethusa (later AO-7) and Warrington (Destroyer No. 30), but that astern refueling method was built on collier processes and conducted in perfect weather—impractical in the unpredictable North Atlantic. Even before 1913, the Navy was transferring oil to the Paulding-class destroyers in support of other Atlantic crossings, such as between the USS Jupiter (Collier No. 3) and Sterrit (Destroyer No. 27) and Walke (Destroyer No. 34), but the methods used are unclear and the amounts transferred apparently were small.

The commanding officer of the Maumee, Lieutenant Commander Henry C. Dinger, and the executive officer/chief engineer, Lieutenant Chester Nimitz, had developed on their own initiative a method for refueling ships in moderate sea conditions after studying the blueprints and conducting surveys of the ships involved. Earlier attempts had arranged the ships in a trailing formation, but the new method brought the two ships together side-by-side, using a towline to maintain position and cradling two fuel lines with a wooden saddle hanging from the cargo booms. This allowed the ships to continue to drive into the sea while fueling. In true jury-rigged fashion, the receiving ships simply poured fuel from the line into open bunker manholes on deck.

When the United States entered the war in April 1917, the Maumee was ordered to a position 300 nautical miles (nm) south of Greenland to refuel U.S. destroyers en route to England. The process worked, and worked well — on 28 May 1917, the Maumee refueled the USS Patterson (Destroyer No. 36), Jenkins (Destroyer No. 42), Drayton (Destroyer No. 23), Paulding (Destroyer No. 22), Trippe (Destroyer No. 33), and Warrington over approximately ten-and-a-half hours. Lieutenant Commander Dinger reported that the towlines he had used could be dispensed with, but prophesized that doing so “would require precise expert judgment and constant watchfulness” — something every conning officer since recognizes as his or her charge during UnReps. The Maumee refueled 34 destroyers over the next three months, setting in motion the first of several revolutions at sea that would lay the foundation for U.S. naval dominance in the 20th and 21st centuries.

After the war, underway refueling was incorporated gradually into regular operations, driven by the War Plans Division of the Navy through the Rainbow War Plans, specifically War Plan Orange (against Japan). Orange included a 4,800-nm Pacific transit, much longer than any previous requirement, and yet it contained no consideration of screening actions, enemy engagements, or securing and establishing forward bases, making the estimated transit too short. Based on these plans, the annual fleet problem war games demonstrated—often through poor outcomes—both the need to refuel at sea and the optimal timeframes to conduct the evolutions. For example, after the Saratoga (CV-3) was left without escorts during her attack run in Fleet Problem IX in January 1929, a requirement was developed for capital ships to refuel smaller ships; though infrequently used, this capability remains a fleet requirement to this day. By the time of Fleet Problems XIII and XIV in 1932 and 1933, major replenishment-at-sea exercises for destroyers and other small ships were included, and the procedures were practiced routinely.

Yet it was not until 1938 that Chief of Naval Operations Admiral William D. Leahy directed the fleet to “take all steps necessary” to develop procedures for refueling battleships, aircraft carriers, and cruisers. The task fell to the commander of Task Force (TF) 7—none other than now–Rear Admiral Chester Nimitz. The size of those ships made the spring and breast lines used by destroyers to maintain station difficult to implement, so he advocated an approach based on the astern-refueling method. Admiral Leahy overrode that recommendation, which resulted in the broadside method becoming the Navy standard across all ships, though larger ships reversed the usual practice and provided the towlines.

New Methods in World War II

Despite the effort put into developing a fleet capability to execute the drive across the Pacific called for in War Plan Orange, the first major large-scale assault conducted acrossan ocean without a forward operating base occurred in the European theater—Operation Torch, the invasion of North Africa. More than 100 ships were refueled by five oil tankers and four Sangamon-class escort carriers that were converted Cimarron-class oilers.

In the meantime, during the initial months of the war, oilers in the Pacific Ocean were supporting raids on Japanese targets as well as operations in the Coral Sea and at Midway. November 1943’s Operation Galvanic, the capture of the Gilbert Islands, would build on that to keep the entire fleet of 200 ships continuously in the combat area by refueling at sea. During early 1945, TF-58 would steam continuously more than 7,500 nm over nearly two months while consuming 117 million gallons of fuel oil and 7 million gallons of aviation gas. As impressive as these feats were, the next major revolution at sea was about to accomplish even more.

In late 1944, Admiral Raymond Spruance had begun preparing to bomb the Japanese Home Islands to eliminate the air threat to the planned invasions of Iwo Jima and Okinawa. He realized that the primary hurdle to keeping his 12 aircraft carriers and associated escorts on station would not be fuel but rather ammunition. It would take only three days for the ships to expend their ordnance, after which they would have to make a 2,000-nm, 12-day sail to Ulithi Atoll and back—meaning only six days of bombing could occur per month. Admiral Spruance directed the development of a method for transferring ordnance and stores at sea, ultimately approving the Burton Method (named for the development team’s leader, Captain Burton Biggs), an adaptation of the pier-side process that used existing cargo winches on both thedelivery ship and aircraft carrier. On 23 February 1945, the USS Shasta (AE-6) conducted the first underway ammunition replenishment, by breaking ammunition out on deck by hand—including rolling bombs across the deck—and then levering it to the USS Bennington (CV-20).

Just a few weeks later, TF-58 sailed to support the upcoming invasions with an ammunition ship embedded among several oilers. Each time the task force expended all its ordnance, it would sail through the night to the rendezvous, then line up along a 40-nm front to make three successive replenishments and breakaways (fuel, then ammunition, then food/stores), before steaming overnight to the next objective. Instead of a three- to four-day engagement followed by a 10- to 12-day interlude, the task force was away for two nights for each three-day engagement. From March to June, TF-58 received 15,398 bags of mail, expended 16,373 tons of bombs, and consumed 2,219 tons of refrigerated foods, 4,005 tons of dry goods, and almost 426 million gallons offuel oil and 26 million gallons of aviation gas—more petroleum than Japan was able to produce or import for the entire year of 1944. This would be repeated when the Fifth Fleet became the Third Fleet, allowing Admiral William F. “Bull” Halsey Jr. and Vice Admiral John S. McCain to conduct ten major attacks on Japan, supported by nine replenishment events between 10 July and 10 August.

Postwar Development

Following the war, in September 1947 the third revolution at sea was set in motion by Captain Edward Pare and Commander Roman Brooks, with Admiral Nimitz’s support and direction. Captain Pare proposed a “one-stop replenishment ship,” a multiproduct ship that could perform a full replenishment in a single evolution instead of three. Simultaneously, the Bureau of Ships (BuShips) was improving the jury-rigged systems in the fleet by establishing a team dedicated to creating more formal systems at the San Francisco Naval Shipyard. The bureau initiated development of designed-for-purpose systems such as a counterweight wire tensioner (the present-day ram tensioner) and recommissioned a captured German vessel as the USS Conecuh (AOR-110) for tests.

At the request of BuShips, Admiral Arleigh Burke called two mobile logistics conferences, in 1952 and 1957. Burke tasked the first conference with engineering efforts to improve the underway replenishment systems, while the second was told to consider the entire subject of mobile logistics support. In attendance was Marvin Miller, a new engineer on the development team in San Francisco, who for the next 40 years would exercise a significant influence in the design and maintenance of all UnRep systems. He would later lead the San Francisco team and, in 1964, would move the entire project to the newly established Naval Surface Missile Systems Engineering Station (NSMSES, pronounced “nemesis”) in Port Hueneme, California (now known as Naval Surface Warfare Center, Port Hueneme Division [PHD]).

NSMSES was established by the missile system program manager to support the numerous new missiles being fielded on board cruisers and destroyers, and the UnRep team was relocated there to aid development of at-sea rearming systems. The initial design was the fast automatic shuttle transfer (FAST), a technically complex and intricate system of systems that automatically carried a missile from the delivery ship to the receiving ship. It was a concept ahead of its time that never quite worked and was plagued by reliability issues, despite more than a decade of attempts.

Ultimately, the engineers at PHD under Miller would develop a new family of systems from the ashes of FAST,named standard tension replenishment alongside method (STREAM), that represented a complete rethinking of all underway replenishment operations. STREAM meant the end of Nimitz’s original scheme, Burton’s ammunition handling, and the too-complex FAST system, each with unique equipment and rigging methods.

STREAM began fleet implementation in 1970. It took another decade, because of funding constraints and the Navy’s intense desire for a fully automated missile system, but Port Hueneme finally completed the fully government-owned build-to-print design of Navy standard machinery. The system has been installed on three new types of replenishment ships: theHenry J. Kaiser-, Supply-, and Lewis and Clark-classes. It has become ubiquitous across U.S. Navy and allied ships, numbering at least 390 identical installations to date.

As the Navy brought STREAM online, it simultaneously began to look to civilian mariners to perform underway replenishment, similar to the British practice. The replenishment-at-sea team at Port Hueneme volunteered to assist Military Sealift Command with the training and engineering maintenance and to serve as the technical consultant. In 1972, Military Sealift Command ran a series of experiments on board the USS Taluga (AO-62) entitled Charger Log II, using a team of civil servants known as the “Taluga Tigers.” Following successful demonstrations, the Naval Fleet Auxiliary Force grew from one ship to 22 T-AOs, 8 T-AEs, and 3 supply ships purchased from the British Ministry of Defense recommissioned as Sirius-class T-AFS ships. Then, as the aged fleet oilers began nearing the end of their service lives, the USNS Henry J. Kaiser (T-AO-187) was introduced to the fleet in 1987. She was the first of a 15-ship class of replenishment vessels designed from the beginning to be operated by civilian mariners.

A System for the 21st Century

In the early 2000s, a requirement to increase the sortie generation rate of Gerald R. Ford-class aircraft carriers led to the development of a new, heavier-capacity design. The transfer requirements were increased from 25 5,700-pound loads per hour to either 25 12,000- or 50 6,000-pound loads per hour. A June 2008 technology evaluation determined that the system’s design should replace hydrostatic transmissions with commercial off-the-shelf variable-frequency drives and a programmable logic control system, while continuing to use many reliable design features of the Navy standard system. Two prototype heavy delivery stations were built—one station was installed at the UnRep test site in PHD and the second on the USNS Arctic (T-AOE-8) in 2012. This new system has proved more reliable, more compact, easier to use and maintain, and less damaging to cargo while preserving complete compatibility with existing STREAM receiving stations at the original load weightbut with increased transfer speeds. A third installation on board the USNS Cesar Chavez (T-AKE-14) was completed in October 2017.

After the successful tests at Port Hueneme and several deployments on board the Arctic, the PHD team and industry partners finalized the new “Electric STREAM” (E-STREAM) fuel and cargo delivery system, preserving backward and forward commonality. The E-STREAM suite of machinery is the underway replenishment system of record for new ship construction beginning with the USNS John Lewis (T-AO-205), lead ship of the fleet oiler replacement program, but at present only the speed improvements and not the heavy lift capability are planned, limiting the amount of cargo and ammunition that can be moved.

Underway replenishment faces several challenges ahead, encompassing the range of delivery issues. The E-STREAM system can handle not only the heavy loads the Gerald R. Ford-class requires but also the lower-weight ammunition and stores demands of the littoral combat ship and future frigate, thanks to the system’s programmable versatility. Vertical replenishment by helicopters is still an option, but E-STREAM gives the Navy a system that will reduce demand on aircraft and allow the aviators and the fleet to operate anywhere and anytime.


VADM M.A. Mitscher, USN, Report of Operations of Task Force Fifty-Eight in Support of Landings at Okinawa, 14 March through 28 May 1945.

R. Hadley, “E-STREAM—Modernization of the Navy’s Family of Underway Replenishment Systems for the 21st Century,” Naval Engineers Journal, 127 no. 3 (September 2015), 73–87.

Matt Cheser “100 Years of UNREP,” The Sextant, 26 May 2017,

M. O. Miller, Underway Replenishment of Naval Ships (Port Hueneme, CA: Naval Surface Warfare Center, 1992).

M. O. Miller, Designing the U.S. Navy’s Underway Replenishment System (Port Hueneme, CA: Naval Surface Warfare Center, 1992).

FADM C. W. Nimitz, USN, “The Little-Known Tale of the U.S.S. Maumee and Her Role in the Development of the Navy’s Secret Weapon,” Petroleum Today, Spring 1961, 9–12.

A. Nofi, To Train the Fleet for War: The U.S. Navy Fleet Problems, 1923–1940 (Newport, Rl: Naval War College Press, 2010).

E. Potter, Nimitz (Annapolis, MD: Naval Institute Press, 2013).

Staff Writer, “In Quasi War, USS Constitution’s Captain Pioneers Naval Maneuver,” Constitution Chronicle, Spring/Summer 2001.

J. J. Teague, “UNREP Today—It’s Booming,” All Hands, 596, September 1966, 8–11.

T. Wildenberg, Gray Steel and Black Oil: Fast Tankers and Replenishment at Sea in the U.S. Navy, 1912–1995 (Annapolis, MD: Naval Institute Press, 1996).


Commander Lukacs is assigned as the ship defense and expeditionary warfare department officer at Naval Surface Warfare Center, Port Hueneme Division. He received his commission in June 1999 after graduating with a bachelor’s degree in architectural engineering from Drexel University in Philadelphia. He has served on the USS Nicholson (DD-982), Anzio (CG-68), and Laboon (DDG-58). He earned master’s degrees in mechanical engineering from the Naval Postgraduate School and defense systems technology from the National University of Singapore.

Published: Wed Aug 08 14:00:04 EDT 2018