Pacific Ocean. (December 18, 2024): Their job is to transfer tons of high explosives, ship to ship, while underway at sea and it is dangerous business. In this photo by Seaman Malina Davy, Lieutenant Commander Maria Relayo inspects ammunition prepared for transport to the Nimitz-class aircraft carrier USS Abraham Lincoln. The ammunition is being delivered by the Lewis and Clark-class dry cargo ship USNS Washington Chambers, the Military Sealift Command’s newest class of dry cargo/ammunition ships.
In the Navy, ammunition is transferred to aircraft carriers primarily through a process called "underway replenishment". The at-sea replenishment concept began in the early 20th century and was used extensively by the U.S. Navy in the Pacific Theatre during World War II. The ability to replenish ship’s supplies while underway permitted U.S. carrier task forces to remain at sea indefinitely. A dedicated ammunition ship like the Washington sails alongside the carrier to perform either a “connected” or “vertical” replenishment of supplies.
Ammunition can be delivered by a "connected replenishment" method (side-by-side transfer) or a "vertical replenishment" using helicopters to deliver cargo directly to the carrier depending on the situation. Sailing alongside a carrier while transferring ammo between two moving vessels is challenging at best. Both ships must run side-by-side at precisely the same course and speed for a long period of time while managing volatile explosives.
Due to this sensitive nature of ammunition, strict safety protocols are in place during all transfer operations and there are well-practiced emergency procedures. Prior to every ordnance transfer, for example, a safety briefing is held to assign responsibilities at every step of the operation. During a transfer, dozens of safety officers roam the deck and hangar bays making sure protocols are followed to the letter. The ship even has airlocks between decks that allow compartments to be flooded with seawater in case of emergency.
Besides explosives, these ships also deliver provisions, spare parts, potable water, and petroleum products to navy ships all over the world. Like their predecessors, these ammunition ships are part of a network that keeps America’s Navy underway and combat ready for extended periods of time.