In coastal navigation, if two horizontal angles between three fixed objects above the sea surface can be determined from a point of observation, two circular position lines are determined that cut at two points. One point of intersection is located in the central object and the other in the observation point itself. The coordinates of the observation point can be determined in various ways; for example, by calculating the radius of the circle – position line, or by graphical construction etc. All of these mehods are sufficiently elaborated in nautical literature.