The U.S. Navy has a new robot -- and it swims like a fish.

I don't just mean it swims "fast," either. Unlike the Navy's other unmanned underwater vehicles -- Seaglider, Knifefish, and now the Echo Ranger -- this one literally swims like a fish. As in, by waving its tail back and forth.


Robo-Tuna and just plain tuna. Can you tell which one is the real chicken of the sea? Photo: Boston Engineering.

Four feet long and powered by lithium-ion batteries, the robot affectionately dubbed "Robo-Tuna" moves at speeds of up to 40 knots "by flipping its tail around," according to Capt. Jim Loper, head of the concepts and innovation department at the Navy Warfare Development Command in Norfolk, Va. The robot is essentially designed as two halves making a whole. The front of the robofish holds sensory gear such as sonar. The rear end is the flipper, which waves left-right, right-left, pushing the water and propelling the bot forward at speeds rivaling those of the Navy's fastest surface warships.

At present, Robo-Tuna is not expected to carry weapons.

Robo-Tuna is a pet project of the U.S. Navy's Chief of Naval Operations Rapid Innovation Cell, or CRIC. It has been in development since at least 2012, and is based on a design from Massachusetts start-up Boston Engineering -- not to be confused with Boston Dynamics, which also builds lifelike robots, and which was bought out by Google (GOOG -1.10%) late last year.

The PETMAN walking robot. Source: Boston Dynamics.

What Robo-Tuna can do

Boston Engineering calls its prototype of the robot the "BIOSwimmer," and says it "can inspect the interior voids of ships such as flooded bilges and tanks, and hard to reach external areas such as steerage, propulsion, and sea chests. It can also inspect and protect harbors and piers, perform area searches, and carry out other security missions."

We're not talking about just short dips in the pond, either. "We're imaging this can loiter for days, possibly weeks on a battery that allows it to maintain its position," Loper said. "This is a sensor we can put out there that matches in with the local [sea]life."

Furthermore, website Military.com noted that if Robo-Tuna is paired with another CRIC-developed technology -- a Suspended Undersea Raw Fiber cable that can spool out from a mothership to lengths as great as 60 miles -- Robo-Tuna might be tethered to the mothership, relaying sensory data instantaneously. Such a cable might also be designed to supply power to Robo-Tuna, keeping it in operation indefinitely.

What Robo-Tuna means to the U.S. Navy
Of course, Robo-Tuna's biggest benefit presently is that it can swim independently, and at very high speeds, without need for a tether. This makes it ideal for missions like patrolling within cluttered environments such as ship ports, or inspecting underwater shipwrecks or damaged oil platforms. The lack of a tether makes the vessel more maneuverable than tethered remotely operated vehicles such as the submersibles designed by Oceaneering International (OII 1.44%).

Robo-Tuna's small size and shallow "draft," meanwhile, open up the possibility of using the vessel to patrol shallow waters such as lakes, rivers, and other inland waterways. Perhaps counterintuitively, Robo-Tuna's small size also might give it a bigger potential market -- because it will fit aboard smaller vessels such as the Navy's fleet of Cyclone-class Coastal Patrol boats, which would also have more use for a shallow-draft robosub.

Simply put, Robo-Tuna might be able to perform missions that Boeing's (BA -0.24%) bigger Echo Ranger cannot.


Stretching 18.5 feet in length and weighing in at 5 tons, Boeing's Echo Ranger is much bigger than Robo-Tuna. Photo: Boeing.

What Robo-Tuna means to you
From an investor's perspective, all of this makes Robo-Tuna an interesting proposition. Built by privately held Boston Engineering, it's not a product we can invest in yet. But then, up until just a few months ago, Boston Dynamics was privately held as well -- and it got bought out by Google at an estimated $500 million.

Will Robo-Tuna -- and Boston Engineering -- go that route as well? If they do, iRobot (IRBT -0.14%) would certainly be a likely bidder. Robo-Tuna is closest in size -- and the biggest competitive threat -- to iRobot's own Seaglider UUV. But Boeing, Oceaneering International, and even new entrants to the underwater robotics market such as General Dynamics (GD 1.17%) could all come knocking on Boston Engineering's door if the Navy decides it likes this new aquatic robot.

Finally, as we saw with the Boston Dynamics acquisition, Google seems enthused about robots that mimic the movements of carbon-based lifeforms, too. Plus, Google has more cash on hand than the combined market caps of iRobot, General Dynamics, and Oceaneering International, and more cash on hand than these three, plus Boeing, could muster as well.

Should a bidding war ever break out for Robo-Tuna's maker, I'd bet on Google running away with the prize.

Meet the Cheetah -- yet another life-imitating robot that Google acquired when it bought Boston Dynamics. Photo: Boston Dynamics.