DARPA Wants Help Developing a ‘Sea Train’ of Unmanned Warships

Sea Hunter, an entirely new class of unmanned sea surface vehicle, recently completed an autonomous sail from San Diego to Hawaii and back.

Sea Hunter, an entirely new class of unmanned sea surface vehicle, recently completed an autonomous sail from San Diego to Hawaii and back. Moraima Johnston/Navy

The Pentagon’s research arm is looking to produce technologies for a new class of long-distance unmanned surface vessels.  

The military is exploring the viability of unmanned surface vessels, or USVs, to conduct a range of dangerous cross-ocean missions without a crew on board. But while the smaller, versatile watercraft can be useful for tasks involving surveillance, logistics, electronic and expeditionary warfare and offensive operations, their size, shape and other components have proven at times to limit the vessels’ ability to endure choppy waves. 

According to a broad agency announcement unveiled in late 2019 and launched this week, the Pentagon’s research arm aims to improve the long-range operational capabilities of the Navy and Marine Corps’ USVs by creating “sea trains” of four or more physically connected vessels, or vessels that aren’t connected but sail in coordinated formations. The ultimate goal is to develop systems of smart, crewless warships that can travel thousands of ocean miles and perform their own duties, all while “exploiting wave-making resistance reductions.”

“The [Defense Advanced Research Projects Agency] Sea Trains program seeks to revolutionize the next generation of unmanned surface vessels,” officials said in the announcement.

Through the program, DARPA envisions the development of a four-vessel-or-more system that can persist through arduous transits of about 7,480 miles, then disaggregate and conduct their own tasks, or “independent yet collaborative operations consisting of transits, loiters, and sprints in varied sea state conditions,” for about 1,150 miles. The vessel will then reassemble for transit as the connected Sea Train for another nearly 7,500-mile journey—all without human intervention. The agency is open to any technical approaches that proposers wish to offer but highlighted three that could potentially achieve the overall concept. Officials recommend fleets of connected or connectorless Sea Trains that essentially create a mid-body for the vessel to decrease wave-making resistance while also allowing for the vessels to separate and conduct tactical missions independently. The agency also suggests “formation sea trains,” or a fleet made up of four or more vessels that travel closely and exploit wave interference between one another while in transit.

“DARPA is very interested in nontraditional approaches that reduce risk early in the program. Early, aggressive, and insightful modeling, analysis, and testing is encouraged and desired,” officials wrote in the BAA. “Potential early failures that burn down risk and lead toward a more capable product are encouraged.”

The program is anticipated to envelop two phases and last for 36 months. The first phase will encompass conceptual design, analysis, simulation and scaled model testing, and the second will include updates and additional testing. DARPA said funding will depend on the quality of proposals received, and the availability of capital at hand. 

Participants will also have to address two technical areas over the course of the program. For the first area, researchers will need to develop a conceptual design of an integrated system comprised of the vessels’ hull form, connectors, propulsion and gap mitigation techniques. For the second technical area, participants will be expected to create a dynamic “open-standard, autonomous” control architecture that can monitor environmental conditions the vessels endure in the middle of the ocean, their alignment and spacing and “control solutions to maximize Sea Train efficiency and seaway survivability.”

Those who wish to participate in the project must submit proposals online by Feb. 20.