Encouraged by the success of UAV (unmanned aerial vehicles), the U.S. Navy has developed a prototype USV (unmanned sea going vehicle.) It's called Spartan and is 23 feet long, can carry 1.5 tons of gear and can stay out for 5-48 hours (depending on fuel use). A satellite link can be used to keep the USV connected with the ship (or aircraft) carrying it's controller. The Spartan is a rigid hull inflatable boat that can move at speeds of over 90 kilometers an hour. It's is highly maneuverable. Using onboard videocams and radar, the remote controller uses a joystick and other controls to maneuver the USV. Like UAVs, the USV would be sent into particularly dangerous situations, or those where a larger vessel would be spotted. Off the shelf components are being used, and the army is investing some of the $55 million that is being spent over the next six years for building and testing prototypes. The army wants the USV for river operations, which can be very dangerous because of enemy troops hiding in vegetation on the banks of narrow waterways. The army could cover its riverine USV with Kevlar fabric, to provide some protection against bullets and shell fragments, although at the cost of several hundred pounds of carrying capacity. The navy sees the USV as an excellent naval mine hunter, and a scout vehicle for marine or SEAL operations. The USV could also be equipped for anti-submarine warfare, especially in shallow coastal waters where small diesel-electric subs can silently lurk, waiting for a shot at enemy ships.