Accuracy Contours of a Ship's Position

Abstract

As the accuracy of a ship's position fixed by the cross bearing method or the horizontal sextant angle method is determined by way of functions of distances and intersecting angles, in most cases, the closer one stands near any object the better he can get a highly accurate position, and on the contrary, the farther away from it, the poorer accuracy he can obtain. However, the extent of inadequate accuracy is subject to the relation between the three objects and the observation point, so it is not easy to know the whole aspect. To know them, the author calculated the probability densities of every point, and draw accuracy contours of the ship's positions. [Fig.3 (a) (b) (c) (d) (e) and Fig.5 (a) (b) (c) (d) (e)] The process of the drawing of the maps is somewhat troublesome, but if one examines those maps closely, he can see the main points of this paper.