Calculation of the deviation coefficients for marine magnetic compass

Abstract

ABSTRACT Deviation coefficients of magnetic compass are a basis to determine the compass deviation as well as to establish the table for compass deviation which is considered as technical certificate for magnetic compass equipped on board the ship. Normally, magnetic compass correction expert needs to observe the deviation values in main course of compass and then insert them into deviation equation system for obtaining the deviation coefficients. In the existing method, the special courses for requirement are on eight main directions such as (N, S, E, W, NE, SE, SW, and NW). These special courses and respective deviations are replaced into the deviation equation to obtain eight equations. Then, by expanding the equations, the deviation coefficients are found out. However, this method has some drawbacks: The observed courses are special ones; the solution of equation is impossible if the number of observation is less than eight. In this paper, the author suggests a new method to calculate the deviation coefficients of compass quickly by observing the compass’s deviation in any course. This method is easy to carry out and without requirement of deviation observation on special courses.