Original URL: http://www.theregister.co.uk/2010/02/02/unmanned_frigates/

US plans crewless automated ghost-frigates

Mary Celeste class robot X-ships to prowl seas

By Lewis Page

Posted in Science, 2nd February 2010 14:15 GMT

Those splendid brainboxes at DARPA - the Pentagon's in-house bazaar of the bizarre - have outdone themselves this time. They now plan an entirely uncrewed, automated ghost frigate able to cruise the oceans of the world for months or years on end without human input.

The new project is called Anti-submarine warfare Continuous Trail Unmanned Vessel (ACTUV), and is intended to produce "an X-ship founded on the assumption that no person steps aboard at any point in its operating cycle". The uncrewed frigate would have enough range and endurance for "global, months long deployments with no underway human maintenance", being able to cross oceans largely without any human input - communications back to base would be "intermittent", according to DARPA.

In particular, the automated warship would need to avoid crashing into other vessels as it prowled the seas on the business of the US government, a function normally performed by bridge watchkeeping officers. DARPA specifies that the ACTUV must be able to conduct "safe navigation at sea within the framework of maritime law" - that is the International Rules for Prevention of Collisions at Sea, aka "Rule of the Road", which Royal Navy officers have to memorise almost word-perfect.

Then, while weaving in and out of other ships, the crewless frigate must be able to stay on the trail of a well-nigh silent diesel-electric submarine running beneath the waves. Such subs are operated - albeit in small numbers - by various minor powers around the world, and are considered by some in the major navies to be a very serious threat.

DARPA's idea would be that every time such a sub put to sea or was otherwise at a known location, an ACTUV would be put onto its tail - freeing up hugely expensive manned ships and subs from routine shadowing work. The thinking is that following such a submarine is fairly easily done compared to finding it in the first place.

That might be true in this case, as DARPA specify that the ACTUV should be able to carry out "continuous overt trail of threat submarines", as opposed to following them secretly as manned US forces might. The robo-frigate would be able to simply get a lock on its prey using powerful active sonar, sending loud "pings" of sound into the sea and detecting the echoes from the sub.

It could then hang close on the sub's tail where active sonar tracking is easy, as it would have "propulsive overmatch" - ie it would be much faster. Nuclear submarines can be speedy enough to lose a surface ship in some circumstances, but this isn't feasible for a diesel-electric boat. Better still, there would be no need for expensive silencing on the ACTUV (of the sort seen on British Type 23 frigates, for instance) as it would expect to be using active sonar anyway.

But who would give the cocktail parties?

Normally, lurking right on top of a hostile sub making lots of noise would be seen as quite a dangerous plan for a frigate captain. Should an actual war break out, the sub might well be able to torpedo the ship before it could itself be destroyed. But this wouldn't be such a disastrous result in the case of an ACTUV. As DARPA puts it: "A low cost, unmanned platform creates a disruptive change in ASW operational risk calculus."

Or in other words it doesn't matter too much if you lose the odd robo-frigate. Particularly as the enemy sub would then have to make a top-speed submerged dash away from the burning wreck of its ACTUV shadower, in order to avoid getting picked up again and promptly sunk by responding ships or aircraft.

Unfortunately for diesel-electric submarine captains, the sub's batteries are only good for one such sprint before running almost flat: which would leave it out of juice not far from the scene of its crime, unable to get further except maybe at a crawl. In theory it might put up a snorkel mast to run its diesels and recharge its batteries - or flee on the surface - but this would be very dangerous with hostile ships and aircraft about, as radar reaches much further and more reliably than sonar does.

All in all, quite a cunning idea then. Rule-of-the-road navigation should be easy enough to automate (for all that boneheaded officer trainees sometimes struggle to master it) and sonar tracking shouldn't be too hard when you can go as close in and make as much noise as you like. And an unmanned ship should not only be cheaper to run, it might be possible to make it much cheaper to build - and yet offer better performance:

Conventional naval architecture should be examined in this unmanned system context, which in addition to recouping first order crew support overhead, may offer second order benefits such as relaxed reserve buoyancy margins, dynamic stability limits, and even new platform orientation assumptions. The objective is to demonstrate disproportionate platform capabilities in terms of speed, endurance, sea keeping, and maneuverability.

The program will also maintain a strong focus on exploiting novel system architectures and internal arrangements enabled by being unmanned to explore new construction methods and maintenance approaches to achieve disproportionately low system procurement cost and efficient inter-deployment maintenance.

It certainly tends to bear out the view of those naval personnel who aren't frigate sailors by trade: that the only thing frigates really do which couldn't be done better by a robot is give show-the-flag cocktail parties in foreign ports.

No doubt that's an overly harsh assessment. Even so, with the coming crunch on government spending and aspirations to buy new carriers and jets to fly from them - not to mention the fact that crewed frigates are scarcely a very effective means of dealing with common-or-garden thugs with guns either - perhaps the Royal Navy too should be thinking along these lines.

Needless to say, it isn't.

Meanwhile, it seems to us that there's only one possible name for the first ghostly, crewless X-ship of the class. ®

Lewis Page spent 11 years in the Royal Navy, largely managing to stay out of frigates but not altogether. Most of the time he was a mine-clearance diver - another field in which humans' jobs are under threat from robots.