The US Defense Advanced Research Projects Agency (DARPA) has successfully completed an initial at-sea refuelling test for the No Manning Required Ship (NOMARS) programme’s Defiant uncrewed surface vessel (USV).  

This vessel is engineered for fully autonomous operation without human crew members.  

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The Uncrewed Maritime Systems Program Office (PMS-406) and USV Squadron 1 (USVRON-1) of the US Navy executed the test using two experimental USVs, Ranger and Mariner. 

The goal was to tackle the challenges of fuelling at sea (FAS) without personnel on board. 

Traditional FAS operations depend on human involvement to manage equipment, which imposes design limitations and potential risks during personnel transfer to USVs in adverse weather conditions. 

The NOMARS FAS method allows for refuelling without any human presence on the USV, although the refuelling vessel is manned.  

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This system aims to replicate standard refuelling procedures to ease the transition for Military Sealift Command (MSC) oiler crews. 

The DARPA has collaborated with MSC’s Taluga Group to guide the FAS system and its operational concept development. 

During the test, the USV Ranger was outfitted with a receiving station indicative of the one planned for NOMARS USV Defiant while the USV Mariner was equipped with a custom-designed refuelling station by Serco, the programme’s prime contractor.  

The trial successfully demonstrated all aspects of the system’s operational concept, including the transfer and connection of the refuelling probe and the simulation of fuel transfer using water.  

The success of this test, supported by PMS-406 and USVRON-1, paves the way for the next phase of testing with the NOMARS USV Defiant during its upcoming sea trials.  

The Defiant, a 180ft, 240t lightship, is nearing the end of construction and is set for a multi-month sea demonstration in spring 2025.  

This announcement follows DARPA’s announcement in August 2022 that the NOMARS programme had entered its second phase. 

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