merbs writes: Early next year, DARPA will begin testing a 132-foot unmanned submarine-hunting ocean drone in San Diego. Slapped with the cumbersome title of Anti-Submarine Warfare Continuous Trail Unmanned Vessel (ACTUV), it's designed to do exactly that: track stealth submarines from the surface, quietly and autonomously. "The 132-foot-long, 140-ton ACTUV is being built by Leidos at the Vigor Shipyard [formerly Oregon Iron Works] in Clackamas, Ore. The vessel is about 90 percent complete. The hardware of the systems is complete, with software being engineered presently." Using one of these drones would cost "about $15,000 to $20,000 per day, compared with a destroyer that costs about $700,000 per day to operate."