Somewhere, about 300 yards out from the Fort Story beach, three old trucks or cars had been dumped. On the stern of the 511 Engineer Dive Detachment′s new 26-foot boat, Sgt. Kyle Ferguson was peering at the cloudy brown and yellow display on his computer trying to spot them. “We’re good, on the track,” Sgt. Carlos Ortiz, at the wheel, called back. “What’s your depth? Ferguson replied, still .