The writer has drawn accuracy contour maps of ship's positions fixed by cross bearing method, horizontal sextant angle method and Loran aid. The accuracy of the fix is shown by the probability density. The process of the drawing of the maps is somewhat complicated, but if the reader examines the contour maps (Fig.2, Fig.4, Fig.7 A, B and Fig.8 A, B, C) and the discussion on the maps, he may see the main points of this paper. The patterns of these contour maps are rather similar to one another and we can readily learn from these maps the degree of accuracy of a position fixed by means of objects or radio stations.