Navy’s Sea Hunter Drone Ship Is Getting A New Owner, New Abilities, and a Sister

The service has taken over the project from DARPA and is looking to transform it from an experiment to an operational asset as fast as possible.

byJoseph Trevithick|
U.S. Navy photo


The U.S. Navy is now fully in control of the revolutionary Sea Hunter trimaran drone boat and already in the process of acquiring a second example. The service is still exploring just what missions these craft could perform, but the first one could be ready for operational testing by the end of the 2018 in one of a number of different roles, from sub- or mine-hunting to acting as an unmanned, floating communications node.

On Jan. 30, 2018, the Defense Advanced Research Projects Agency (DARPA), one of the Pentagon’s main research and development arms, announced that it was formally turning over Sea Hunter to the Office of Naval Research (ONR). DARPA first began work on the unmanned surface vessel, also known as the Anti-Submarine Warfare Continuous Trail Unmanned Vessel, or ACTUV, in 2010, and ONR became a partner in the project four years later. The Navy will now continue experimenting with Sea Hunter as part of its Medium Displacement Unmanned Surface Vessel (MDUSV) program.

“ACTUV’s move from DARPA to ONR marks a significant milestone in developing large-scale USV technology and autonomy capabilities,” Alexander Walan, a program manager in DARPA’s Tactical Technology Office (TTO), said in an official statement. “Our collaboration with ONR has brought closer to reality a future fleet in which both manned warships and capable large unmanned vessels complement each other to accomplish diverse, evolving missions.”

Oregon Iron Works, now called Vigor Works, a firm that specializes in exotic, experimental, and stealthy watercraft, built Sea Hunter in 2016. Leidos, which manufactured the first vessel’s navigation system, has since taken over the project entirely. In December 2017, that company received a $35.5 million contract from the Navy to build the second hull, referred to as Sea Hunter II. The bulk of that work would occur at a shipyard in Gulfport, Mississippi. The deal also included an unspecified number of option periods that could raise its total value to more than $43.5 million for continued work through 2020.

Video thumbnail

It's not clear what missions the Navy has envisioned for Sea Hunter and its sister ship, but as the DARPA program name suggests, the original focus was on developing an experimental unmanned vessel capable of locating and tracking enemy submarines, primarily using a high frequency fixed sonar array. In August 2017, DARPA and ONR tested Sea Hunter with a mine countermeasures package, which could be another possible mission set for the boat.

Both roles make good sense for an unmanned system such as Sea Hunter. A group of MDUSVs could more readily search a wider area for both hostile subs and mines and similar underwater hazards that larger warships and might be able to safely navigate narrow of shallow waterways to find those threats. The drone boats could also scout well ahead of manned ships for the enemy, reducing the chance that threats could avoid detection and get close to particularly high value assets, such as aircraft carriers or amphibious assault ships.

Submarines are already a growing threat to the Navy’s surface ships, especially as advanced diesel-electric types and air-independent propulsion (AIP) technology continue to become more affordable. In addition to making these conventional submarines quieter and harder for sonar to detect, AIP systems also allow them to remain submerged for significantly longer periods of time than their predecessors, giving them capabilities in this regard closer to those of nuclear submarines, but at fraction of the price and overall complexity of those boats. 

Among America’s potential near-peer opponents, China in particular is working to dramatically expand its submarine capabilities, including with new AIP-equipped submarines. They’re also eager to export them, which could put those designs in the hands of smaller, regional adversaries. Russia is also slowly overhauling its submarine fleet and adding advanced diesel-electric types, as well as making those latter designs available to international customers.

Perhaps more pressing is the apparent surge in submarine development in North Korea. The country continues to grow a small, but significant fleet of types best suited to coastal defense and for inserting commandos, but is also working on larger designs capable of firing ballistic missiles, possibly carrying nuclear warheads.

And while it rarely gets the same amount of public attention, the threat of naval mines is also very real and is a capability that even smaller nations could employ to great effect in a crisis. Mining remains one of the most logical ways that Iran could make good on threats to cut off the Strait of Hormuz to foreign navies and international shipping. Improvised mines have also begun to appear off the coast of nearby Yemen, where Iranian-backed Houthi rebels are employing a variety of asymmetric weapons against warships from the Saudi-led coalition operating in and around the country.

For the U.S. Navy, smaller unmanned boats such as Sea Hunter would also be more cost effective than relying entirely on larger warships or other assets, such as aircraft or aerial drones, to search for and counter these threats. It could also help reduce the strain on the Navy’s manned surface fleets. These points are particularly important as the service struggles to achieve its goal of having a total of 355 ships and in finding sufficient numbers of sailors to man and repair facilities to support the fleet it has now.

“ACTUV represents a new vision of naval surface warfare that trades small numbers of very capable, high-value assets for large numbers of commoditized, simpler platforms that are more capable in the aggregate,” Fred Kennedy, the director of DARPA’s TTO said. “The U.S. military has talked about the strategic importance of replacing ‘king’ and ‘queen’ pieces on the maritime chessboard with lots of ‘pawns,’ and ACTUV is a first step toward doing exactly that.”

Shots of Sea Hunter at Vigor prior to her delivery. , DARPA

But where ONR’s follow-on MDUSV program might be most game-changing is in its plans to get Sea Hunter and Sea Hunter II to work autonomously in concert with each other or other ships and assets, such as maritime patrol aircraft or aerial drones. Sea Hunter has already demonstrated an ability to avoid other ships and obstacles on its own.

Networked together and operating in an autonomous mode, Sea Hunter and its sister ships might be even more flexible, alerting each other to potential undersea threats or points of interest. With robust data-links they could exchange data with manned ships or other assets, further narrowing down search areas and make it less likely that the target would be able to escape after an initial detection. The ability of an unmanned surface vessel such as Sea Hunter to find an enemy submarine and doggedly keep a fix on it was a key goal of the original ACTUV project.

Video thumbnail

The Navy is already heavily invested in developing an interconnected series of networks that links ships, aircraft, and unmanned systems in the air and at sea together, derived from an initial air defense focused concept known as the Naval Integrated Fire Control-Counter Air, or NIFC-CA. At the same time, ONR has been experimenting with swarms of small unmanned aircraft and surface vessels, research and development that it might be able to leverage into its work with Sea Hunter.

The Navy also wants to use Sea Hunter as the starting place for an eventual design that will be cover thousands of miles while operating on the open ocean for months at time. With that kind of range, endurance, and autonomy, the Navy would be able to maintain anti-submarine patrols over wide areas for extended periods, all without having to use a single ship, submarine, or sailor of its own.  

Those capabilities mean that, depending on their final configuration, the drone boats could similarly guard inlets, harbors, and other sensitive maritime locations 24 hours, seven days a week without having to take breaks, further relieving the strain on the service's manned components. Whether close to home or out on the open seas, a Sea Hunter "class" of vessels could easily free up manned warships for more demanding missions or simply reduce the Navy's overall operational workload to allow for crews to get more rest in between cruises. 

With all of these features, the final production Sea Hunters, or whatever craft they might evolve into, might find themselves taking on a wide array of combat missions and other tasks beyond just sub-hunting and mine-sweeping. There are already plans for anti-submarine weapons so the drone boats can engage targets directly and additional sensor suites to gather visual and electronic intelligence. In 2016, DARPA and ONR tested the drone boat with a parasail-mounted sensor system known as the Towed Airborne Lift of Naval Systems (TALONS).

Video thumbnail

In August 2017, Sea Hunter took part in another exercise, Trident Warrior 2017, along with the aircraft carrier USS Theodore Roosevelt, the Ticonderoga-class cruiser USS Bunker Hill, three Arleigh Burke-class destroyers, and the Los Angeles-class attack submarine USS Pasadena. During those drills the drone boat carried an experimental long-range laser communications system, at times transmitting up to 10 gigabits of voice, video, and other data, highlighting a potential role as a communications node.

The Navy appears to be eager to start examining just what Sea Hunter might be able to do and according to DARPA, the service could begin operational evaluations or actual field testing by the end of 2018. In February 2017, Captain Chris Sweeney, Deputy Director of Surface Warfare for Aegis and Ballistic Missile Defense, told USNI News that the service was considering forming an “experimental squadron” consisting of Sea Hunter, the first-in-class USS Zumwalt stealth destroyer, an Arleigh Burke-class destroyer, and a Littoral Combat Ship, or LCS, for this purpose.

But whether or not the Navy creates this unit, it seems likely that we will be seeing more of Sea Hunter in various tests and exercises in any number of different roles.

Contact the author: