In using the data available during the conduct of a bearings only approach two rather different procedures are usually followed.

One is to attempt the complete solution for range, course and speed by taking usually six bearings while maneuvering the submersible in a rather specialized way. The other methods involve the use usually of three bearings and an assumed range or speed to calculate the course and the speed or range (whichever was not assumed).

The purpose of this paper is to show that using four bearings it is first actually possible to solve the problem completely (range, course and speed solution) in a very general way, and second to give in detail several simple, direct methods for making such a solution without restricting the motion of the submersible.