The Defense Advanced Research Projects Agency’s (DARPA) No Manning Required Ship (NOMARS) program recently completed its first successful test of at-sea refueling designed for use with the program’s unmanned surface vessel (USV) Defiant. Defiant is intended to operate autonomously for long durations at sea and is designed from the ground up with no provision, allowance, or expectation for humans on board, DARPA said in a statement.
The test was conducted by the U.S. Navy's unmanned maritime systems program office and USV Squadron 1, in collaboration with DARPA. The test involved two experimental USVs, Ranger and Mariner. Ranger carried a receiving station designed to replicate the system planned for the NOMARS Defiant, while Mariner was equipped with a refueling “mini-station”, developed by Serco Inc.
DARPA highlighted that fueling at sea (FAS) for USVs presents unique challenges as current methods typically require personnel to manage lines and hoses. The agency noted this challenge necessitates designs that account for human safety, and increases operational complexity. DARPA said the NOMARS FAS system, in contrast, is designed to operate without humans aboard the USV, streamlining vessel design and reducing risks associated with personnel transfers in adverse sea conditions.
During the test, DARPA said the team successfully demonstrated key refueling operations, including passing the lead-line, connecting the refueling probe, and pumping water. This marks the first on-water test of the system, with all components performing as expected, the company said.
The next phase of testing will involve the USV Defiant during its sea trials. DARPA noted the 180’, 265-ton lightship is nearing completion and is set to begin a multi-month at-sea demonstration in spring 2025.
