DARPA is testing a large, unmanned sub-hunting surface vessel (USV) dubbed Sea Hunter (1). This is an interesting concept and well worth the effort. The vessel is a bit smaller than a Cyclone class patrol ship and is intended to track and trail submarines using on-board sonar. It is capable of 27 kts and can operate up to Sea State 5 and survive up to Sea State 7. Endurance is 70 days. Cost is $20M. The vessel is currently unarmed although adding weapons would, presumably, not be difficult.
The type of sonar(s) has not been specified and there is no indication whether it is active, passive, or both. Note, though, that the size of the vessel is quite small. Thus, the sonar will be small and not very powerful. This means that the search volume will be correspondingly small. This is not a vessel that's going to search and sanitize a thousand square miles every minute! Lacking any definitive information, I see this as a somewhat more powerful, mobile sonobuoy but not much more. Other than dumb luck, I don't know how it will acquire a target to track.
What’s interesting is to contemplate the intended mission. From what little the Navy has revealed, the mission is to find and trail enemy submarines. During peacetime, this is a good way to keep track of enemy submarine movements and, presumably, gather acoustic signatures data. During war, the mission would presumably be the same (ignoring weaponization of the vessel), however, the usefulness becomes questionable in much the same way as the P-8.
These vessels are not claimed to be stealthy and they have no self-defense, whatsoever. In fact, they're fairly large, as unmanned vessels go and, I would assume, quite readily detected. In war, they would simply be floating targets and easily eliminated. The obvious question, then, is what is the wartime role?
One can imagine swarms of these vessels sent to chokepoints to pick up submarine movements. As long as the chokepoint is under friendly control this will work. Conversely, sending swarms into enemy controlled air/water space would simply be throwing them away. While the $20M price tag confers a degree of expendability, simply throwing them away is pointless. Of course, if we were to build thousands of them, the price tag would come down somewhat, one would hope.
Perhaps the vessels can be used to scout ahead of ship movements although, again, how to keep them afloat in the face of enemy action is a mystery.
Further compounding the problem is the requirement to maintain contact with, and control of, the vessel. As we’ve often discussed, in war the vessel will have to operate in a heavy ECM environment and the ability to maintain communication is suspect under those conditions.
|Sea Hunter USV|
As with the P-8, I’m missing the wartime role.
Another interesting aspect of the peacetime role is the unmanned nature. Given
’s willingness to forcibly confront the China (EP-3 forcedown and various naval encounters) I
strongly suspect that the Chinese won’t hesitate to sink these boats. It’s quite easy to deny any knowledge of an
unmanned vessel that vanishes at sea.
UAVs disappear all the time. Why
not USVs? These vessels would also
provide excellent live fire training exercises for Chinese submarines. Not to neglect the Iranians, if they’re
willing to seize US boats and crews, I can’t see them not seizing an unmanned,
defenseless vessel. I assume US and NKorea would similarly seize or destroy any
vessels they find. If deployed in this
role, I suspect we’ll see large numbers of the vessels disappear for no
apparent reason. Russia
Looking at the broader picture, the third offset strategy championed by Bob Work is filled with this kind of highly questionable product that sounds good on paper but fails the test of combat logic. We’re banking on a highly questionable strategy while conceding numerical superiority and quality. That’s a good way to lose a future war.
(1)Breaking Defense website, " DSD Work Embraces DARPA's Robot Boat, Sea Hunter”, Sydney J. Freedberg Jr.,
April 07, 2016,