Determining Residual Deviation and Analysis of the Current Use of the Magnetic Compass

Abstract

The use of electronic compasses and satellite systems has led to the magnetic compass becoming a secondary means of navigation. Yet this means of navigating is not only not obsolete, it is a necessary backup device: the construction simplicity of the magnetic compass, without electrical windings, rotating elements, and control units, remains resistant to power losses, hardware malfunction, and thus is reliable under the harshest conditions. This durability, however, comes at some cost; the magnetic compass is influenced by ships’ permanent and transient magnetism, cargo gears. For the proper use of a magnetic compass, it is necessary to perform an adjustment to determine the residual deviation at regular intervals. The paper analyses selected methods to manage this, and to identify the main features of classical methods. The research was supplemented by a study carried out during the practical compensations of the magnetic compass at sea and by a survey among navigation officers on its basic requirements for proper use. The results indicate insufficient inspection of the magnetic compass. Further, an investigation into the causes of deviation delivers information regarding the causes under varying conditions including type of ship and latitudinal circumstances. This paper presents findings and recommendations to improve the compensation and use of the ships magnetic compasses.