You've heard of UAVs, unmanned remote controlled military aircraft; but what about USVs? Standing for Unmanned Surface Vehicle, a USV is quite simply an unmanned boat, like Zyvex Marine's Piranha concept. We've looked at USVs before, and the Piranha specifically in early 2010; but what was then a prototype under development is now a fully-fledged production craft, having shipped its first unit last November.