Abstract: A rope is pulled between an end member such as a parachute forming a sail with regard to the wind and a main floating anchor located at the other end. This rope is connected at chosen intervals to captive-balloons, each associated with secondary floating anchors. The captive-balloons are chosen to be sensitive to the wind in order to incline themselves with respect to the floating anchor and to respectively support decoys formed by sets of retroreflective trihedrons. Advantageously, the decoys are individually connected in their lower part to floating bodies such as slightly inflated and loaded balloons. The invention has application, in particular, to the simulation of large surface ships.