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Military Sealift Command operates the T-AO Fleet Replenishment Oilers as a component of the Combat Logistics Force (CLF). These tankers, designed to supply the US Navy and allied forces with diesel and jet fuel at sea, help naval vessels stay on patrol longer without needing to refuel in port.
The tanker fleet includes the Kaiser Class (T-AO 187-204) and the newer John Lewis Class (T-AO 205 and beyond). Fifteen Kaiser Class vessels were built starting in 1986, but they are being phased out in favor of the John Lewis Class; the Walter S. Diehl (T-AO 193) has already been decommissioned.
Following the 1989 Exxon Valdez oil spill and the subsequent passing of the Oil Pollution Act of 1990 (OPA 90), oil tankers are required to have double hulls; however, only the USNS Patuxent, USNS Laramie and USNS Rappahannock have double hulls. All other Kaiser class T-AOs are single hull tankers.
The contract for the John Lewis Class tankers was awarded to General Dynamics NASSCO in 2016, and production began in 2018. The first of these ships, the USNS John Lewis, was delivered to Military Sealift Command on July 27, 2022. Delivery of 20 total John Lewis Class Fleet Replenishment Oilers are planned to replace the Kaiser Class tankers.
Tankers operate throughout every fleet, with schedules that can range from long-term sea assignments to frequent port calls. Many mariners appreciate that tankers have access to a wider range of piers and ports. Since they do not hold ammunition, they do not need to anchor out and can pull directly into port.
Tanker assignments are often seen as standard and not particularly high-paying. However, many mariners enjoy the unique aspects of tanker life, including the steadier pace and consistent operations. Some CIVMARs even choose to stay on tankers if they prefer the ship or its schedule. With a smaller crew size compared to other CLF vessels, tankers tend to have a more experienced, if older, crew. If you’re considering a tanker assignment, you might find that being a “Tanker Trash” is more enjoyable than you’d expect—give it a try and see for yourself!
Kaiser Class
Propulsion: Two fully automatic diesel engines, twin shafts, controllable-pitch propellers, 32,540 horsepower.
Length: 677.5 feet (206.5 meters).
Beam: 97.5 feet (29.7 meters).
Displacement: 41,225 tons full load (double hull), 40,900 tons full load (single hull).
Speed: 20 knots (23 mph).
John Lewis Class
Propulsion: Twin shaft, geared medium speed diesels with PTO generators/PTI
Length: 227.3 meters
Beam: 32.2 meters
Displacement: 22,173 metric tons (lightship)
Speed: 20 knots
Operational Characteristics
Kaiser Class
Cargo Fuel Capacity- About 7.5 million gallons
John Lewis Class:
Cargo Fuel Capacity: About 6.8 million gallons
Crew Size
Kaiser Class: 74-89
John Lewis Class: 99
Military Detachments (if applicable):
Air Detachments: T-AOs do not have embarked air-detachments.
Security Detachment: T-AO vessels will typically only pick up a security detachment during a 5 th fleet (Middle East) deployment.
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