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 20^th 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.