2 HANDBOOK OF MAGNETIC COMPASS 



4. Precautions. 



(a) Determine transient deviations of compass from gyro 



repeaters, doors, guns, etc. (ch. IX). 



(b) Secure all effective magnetic gear in normal sea-going 



position before beginning adjustments. 



(c) Make sure degaussing , coils are secured before begin- 



ning adjustments. Use reversal sequence, if neces- 

 sary (art. 128). 



(d) Whenever possible, correctors should be placed sym- 



metrically with respect to the compass (arts. 32 

 and 102). 



5. Adjustments. 



(a) Place the Flinders bar according to best available 



information (arts. 77, 97, and 98). 



(b) Set spheres at mid-position, or as indicated by last 



deviation table. 



(c) Adjust heeling magnet, using balanced dip needle 



(ch. XV). ' 



(d) Adjust degaussing compass compensating coil cur- 



rents (ch. X). 



2. B. Adjustments at sea. — ( These adjustments are made with the 

 ship on an even keel and after steadying on each heading. When using 

 the gyro, swing frotn heading to heading slowly and check gyro error 

 hy sun's azimuth or ranges on each heading {art. JfS). Be sure gyro 

 is set for the mean speed and latitude of the vessel. Note all precau- 

 tions in section A-^ above. '"''Jig King'''' international code signal 

 should he floion to indicate such work is in progress. Chapter V 

 discusses methods for placing the ship on desired headings) . 



1. Come to a cardinal magnetic heading, e. g. east (090°). 



Insert fore-and-aft B magnets, or move the existing 

 B magnets, in such manner as to remove all deviation. 



2. CovciQ to 2i south (180°) magnetic heading. Insert athwart- 



ship C magnets, or move the existing G magnets, in 

 such manner as to remove all deviation. 



3. Come to a west (270°) magnitic heading. Correct half 



of any observed deviation by moving the B magnets. 



4. Come to a north (000°) magnetic heading. Correct half 



of any observed deviation by moving the C magnets. 



{The cardinal heading adjustments should now be complete'). 



