USNS Walter S. Diehl

USNS Walter S. Diehl (T-AO-193) is a Henry J. Kaiser-class replenishment oiler of the United States Navy. She was named after Captain Walter Stuart Diehl, USN, a career naval officer and aeronautical engineer.

Design
The Henry J. Kaiser-class replenishment oilers were preceded by the shorter Cimarron-class fleet replenishment oilers. Walter S. Diehl has an overall length of 206.5 m and a beam of 29.7 m, with a draft of 11 m. The oiler has a displacement of 41353 t at full load. It has a capacity of 180000 impbbl of aviation fuel or fuel oil. She can carry a dry load of 690 m2 and can refrigerate 128 pallets of food. The ship is powered by two 10 PC4.2 V 570 Colt-Pielstick diesel engines that drive two shafts; this gives a power of 25.6 MW.

The Henry J. Kaiser-class oilers have maximum speeds of 20 kn. They were initially built without armaments, but are equipped with small arms and can be fitted with close-in weapon systems if required. The ship has a helicopter platform but not any maintenance facilities. Walter S. Diehl is fitted with five fuelling stations; these can fill two ships at the same time and the ship is capable of pumping 900000 gal of diesel or 540000 gal of jet fuel per hour. She has a complement of 89 civilians (nineteen officers), 29 spare crew, and 6 United States Navy crew.

Construction and delivery
Walter S. Diehl, the seventh ship of the Henry J. Kaiser-class, was laid down at Avondale Shipyard, Inc., at New Orleans, Louisiana, on 7 August 1986 and launched on 2 October 1987. She entered non-commissioned U.S. Navy service under the control of the Military Sealift Command with a primarily civilian crew on 13 September 1988.

Service history
Walter S. Diehl was assigned to the United States Pacific Fleet, serving in the Pacific Ocean, Indian Ocean, and Persian Gulf regions.

On 23 April 2002, Walter S. Diehl was passing through the Strait of Hormuz when six small motorboats sped alongside in an aggressive and threatening manner. Walter S. Diehl fired flares to warn the boats off, but they did not move away. She then opened fire with a .50-caliber (12.7-mm) machine gun and the boats sped off.

On 20 November 2014, Walter S. Diehl collided with the USNS Amelia Earhart (T-AKE-6) during an underway replenishment operation. No injuries were reported.

She was taken out of service and placed in reserve on 1 October 2022.