THEORY OF ADJUSTMENT 27 



error inasmuch as conditions of sluggishness and unsteadiness 

 accompany large deviations and consequently make the compass 

 operationally unsatisfactory. This is the result of unequal 

 directive forces on the compass as the ship swings in azimuth. 



(3) Furthermore, even though the deviations are known, if they 

 are large they will be subject to appreciable change with heel and 

 latitude changes of the ship. 



37. Subsequent chapters will deal with the methods of bringing a 

 ship to the desired heading, the practical procedures of adjustment, 

 and the methods of isolating deviation effects and of minimizing inter- 

 action effects between correctors. 



Once properly adjusted, the magnetic compass deviations should 

 remain constant until there is some change in the magnetic condition 

 of the vessel resulting from magnetic treatment, shock from gunfire, 

 vibration, repair, or structural changes. Frequently, the movement of 

 nearby guns, doors, gyro repeaters, or cargo affects the compass greatly. 



