r screen on board of the ship, consists in determining with respect to said obstacles, taking into account such parameters as distance, speed...http://www.google.es/patents/US4466068?utm_source=gb-gplus-sharePatente US4466068 - Apparatus for the detection and prevention of collision risks in deep sea and coastal navigation B???squeda avanzada de patentes N???mero de publicaci???nUS4466068 ATipo de