The U.S. Navy just took delivery of the largest crew-less surface ship in the world. The Sea Hunter Anti-Submarine Warfare Continuous Trail Unmanned Vessel, or ACTUV, is a 132 foot long, 140 ton drone warship perfectly suited for hunting down enemy submarines.

In recent years, the role drone aircraft have played in America’s military strategy has continued to expand as technology has improved to allow the U.S. military to leverage more of the advantages allowed by autonomous aircraft in a combat zone. Long loiter capabilities, in particular, have proven invaluable to reconnaissance and even offensive operations, but until recently, these benefits have been enjoyed primarily in the sky. The ACTUV aims to change that.

The ship is not only capable of conducting long duration operations without any crew on board whatsoever, the crew cabin needed to control the vessel from the ship is actually removable. It’s been undergoing an array of increasingly complex tests over the past year, and reports indicate that the ACTUV performed so well, DARPA (Defense Advanced Research Projects Agency) actually re-classified the vessel as a reliable platform for a variety of operations. However, one remains this ghost ship’s primary function: to stalk submarines.

“This is an inflection point,” Deputy U.S. Defense Secretary Robert Work said. “This is the first time we’ve ever had a totally robotic, trans-oceanic-capable ship.”

Currently, the ACTUV is not equipped with any weapon systems and would have to rely on manned vessels or even armed drone aircraft to engage enemy ships, but where the drone ship proves its mettle is on long duration sub-hunting missions.

“We’re not working on anti-submarine (technology) just because we think it’s cool. We’re working on it because we’re deeply concerned about the advancements that China and Russia are making in this space,” said Peter Singer, an expert on robotic warfare at the New America Foundation think tank.

Even traditional diesel submarines can remain submerged for weeks on end – far longer than any aircraft could loiter above (helicopters are traditionally used as sub spotters) and often, longer than any crewed ship can afford to wait around for the submarine to surface. The ACTUV, however, can stay on a sub’s tail for months if it has to. Of course, should the Navy ever decide to arm these vessels, their combat applications will only continue to grow.

It’s likely that theses vessels will eventually be operated in mini-fleets, with a single manned vessel in the area coordinating a number of ACTUV ships as they patrol or search for encroaching submarines. In that sense, the drone ship will serve as an autonomous force multiplier that may be crucial against an opponent like Russia or China. Russia, for instance, recently completed development of the most powerful nuclear weapon fielded by any nation’s military in a half century – which relies on a drone submarine delivery method, rather than a traditional ICBM.

If the ACTUV Sea Hunter proves reliable, it’s likely that the U.S. Navy will begin adopting more autonomous vessels, allowing the fleet to grow without increases to some of the most expensive assets the Navy currently maintains: its Sailors.

Images courtesy of DARPA and the U.S. Navy