Abstract The problem of continuous position availability is one of the most important issues connectedwith human activity at sea. Since the availability of satellite navigational systems can be limited in some cases,for example during military operations, we should consider other methods of acquiring information about ship'sposition. One of such methods is to apply information included in a radar image of a coast. The positioningsystem extracts characteristic points from the radar image, identifies them, i.e. assigns correct location to each ofthem, and finally fixes ship’s position using previously identified points as reference points. In this paper, a newmethod of identification of radar image characteristic points is presented which is an adaptation of r-contiguousbitsscheme borrowed from immune systems. The method proposed compares coastlines visible from radarimage points with pattern coastlines generated from navigational chart.