PROBLEMS 



135 



PROBLEM 3 



L. A. T 0900. 



Latitude 38.0° S. 



Declination 15. 0° N. 



Variation 11. 0°W. 



True azimuth 



Magnetic azimuth 



B 



L. A. T 1400. 



Latitude 39. 0° N. 



Declination 21.5° S. 



Variation 9. 0° E. . 



True azimuth . 



Magnetic azimuth 



C 



L. A. T . 1500. 



Latitude 36.3° S. 



Declination 7.0° S. 



Variation 3. 5°W. 



True azimuth 



Magnetic azimuth 



D 



L. A. T 0953. 



Latitude 37. 7° N. 



Dechnation 17. 6° N. 



Variation 13.7° E. 



True azimuth 



Magnetic azimuth 



PROBLEM 4 



1. Magnetic heading differs from true heading by — 



(a) Compass error. 



(b) Variation. 



(c) Deviation. 



2. The Flinders bar is used to correct for — 



(a) Permanent fore-and-aft magnetic fields. 

 (6) Induced magnetism in horizontal soft iron, 

 (c) Induced magnetism in vertical soft iron. 



3. Deperming is employed — 



(a) To reduce the permanent magnetism of the ship; 

 (6) To reduce the magnetism in the soft iron of the ship, 

 (c) To make for better compass adjustment. 



4. Spheres and Flinders bar should be annealed — 



(a) After deperming. , 



( 6 ) After crossing the equator. 



(c) When they become magnetized. 



5. The standard compass is so called because — 



(a) It uses standard size magnets and spheres. 



(6) It is usually in the best location and should be used as a standard 



reference for other compasses, 

 (c) It has a standard size card. 



6. Shielding on a ship is — 



(a) The effect of the compass needles on the spheres. 



(6) The effect of the metal around the compass on the magnetic lines of force, 

 (c) Putting the top on the compass to protect it from the weather. 

 7 If the deviations on a compass were 8° easterly on north and south, and 8° 

 westerly on east and west — 

 (a) The compass needs larger spheres. 

 (6) The spheres need slewing, 

 (c) The compass needs less Flinders bar. 

 8. A ship having a deviation curve indicating no E error at the equator and 

 whose deviation curve shows considerable E error on arriving at New York 

 has — 

 (a) Ipaproper data. 



