HEELING ADJUSTMENTS 117 



the compass position on board ship and adjust the heeling magnet 

 until the needle assumes the balanced condition. 



Theoretically, these methods of adjusting the heeling magnet by 

 means of a dip needle should be employed only with the ship on east 

 or west magnetic headings, so as to avoid heeling errors resulting from 

 unsymmetrical, fore-and-aft, induced magnetism. If it is impractical 

 to place the ship on such a heading, approximations may be made on 

 any heading and refinements made when convenient. 



The dip needle is considered merely as a balance indicator when used 

 for correcting the heeling effects of degaussing. As explained in 

 chapters X and XI, the heeling coil currents are adjusted so as to 

 bring the dip needle back to its original balance, and the position 

 of the weight has little meaning. 



136. In the final analysis a successful heeling magnet adjustment 

 is one whereby the objectionable oscillations due to rolling of the ship 

 (maximum effects on north and south compass headings) are mini- 

 mized. Therefore, the rolling method is a visual method of adjust- 

 ing the heeling magnet or checking the accuracy of the last heeling 

 magnet adjustment. Generally, the oscillation effects due to roll on 

 both the north and south compass headings will be the same. How- 

 ever, some unsymmetrical arrangements of fore-and-aft soft iron will 

 introduce different oscillation effects on these two headings ; and such 

 effects cannot be entirely eliminated on both headings with one setting 

 of the heeling magnet. Therefore, the heeling magnet is generally 

 set for the average minimum oscillation condition. 



