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Underway Replenishment Keeps Our Ships at Sea


Naval Surface Warfare Center, Port Hueneme Division has provided Underway Replenishment (UNREP) engineering services to the Navy’s surface fleet since 1963. UNREP enables aircraft carriers, surface combatants, and amphibious ships to remain underway at sea indefinitely in support of our national interests.


Replenishment while underway, UNREP, involves the transfer of all consumables from supply ships to the customer ships while both are underway. Items such as fuel, food, ammunition, repair or replacement parts, and personnel are routinely transferred at sea.


Navy’s Only Underway Replenishment Test Site

Port Hueneme has the only fully equipped and operational UNREP test site. This test site contains modern constant tensioned fueling and cargo systems with Navy standard equipment that represents the latest configurations for both the delivery and receiving parts of the system. The test site has many uses:


As a test site, it is used to fully test new systems, equipment, and configurations. Any new UNREP development can be thoroughly tested under the controlled conditions, safety, and economy of this dedicated land-based facility.

·       As a training site, it is used extensively to train both Navy and civilian crews. Because the Navy standard equipment installed at the test site represents the latest design and highest population of UNREP equipment in the fleet, the training provided in equipment operation and maintenance, as well as system operation, is the most effective land-based UNREP training available.

·       As a demonstration site, it is used to demonstrate UNREP procedures, systems, equipment, and new developments to sponsors, fleet representatives, VIPs, foreign military representatives, and public and private tour groups.

·       As a fleet technical assistance site, it is used to simulate or duplicate UNREP problems reported by the fleet and to develop special repair procedures.

·       As an overhaul site, it is used to overhaul and test items turned in by the fleet and return them in operational condition.



New UNREP Technology

Our Underway Replenishment experts continue to be busy as the fleet’s full service UNREP agent, maintaining crucial capabilities that permit our Navy to remain at sea for as long as necessary.


At the same time, the UNREP division has embarked on the development of new technology for replenishment at sea. NSWC PHD was selected by the Office of Naval Research (ONR) to conduct the development of a new UNREP transfer system concept to meet expeditionary logistics objectives.


The new technology, referred to as Heavy UNREP, was initiated by the ONR Future Naval Capabilities Program to develop and demonstrate at sea an advanced concept UNREP transfer system. The concept objective is to reduce the current UNREP time by 50 percent, increase capacity to 12,000 pounds, transfer in higher sea states (rough weather conditions) and with a 40 percent reduction in manning.


NSWC PHD’s plan for creating Heavy UNREP will advance UNREP state-of-the-art technology by use of constant tension methodology coupled with tailored transfer options. Included in the planning is the flexibility to service legacy ships.