PROBLEMS 137 



20. In magnetic adjustments it is best to place fewer magnets very close to 

 tlie compass rather than more magnets farther away from the compass. 



21. After deperming, a sliip will need smaller spheres. 



22. Heeling errors, due to pitch, are most noticeable on east and wesi 

 headings. 



23. The D error, once corrected, should remain corrected regardless of changes 

 in magnetic latitude or changes of B or C correctors. 



24. The navigator on crossing the equator from south latitude to north 

 latitude must invert the Flinders bar so as to have the blue end up in north 

 latitudes. 



25. If deviation due to magnetic A is present it will change as the ship 

 progresses toward the magnetic equator because the directive force changes. 



26. On a properly adjusted compass the heeling magnet is the only corrector 

 which corrects for both permanent and induced magnetism. 



27. With all types of compass compensating coil installations, if the amount 

 of Flinders bar is changed the compass compensating coils will have to be 

 recompensated. 



28. A ship traveling on an east heading while practicing gunnery should ex- 

 pect to acquire an easterly B error. 



29. If a ship adjusted at New York goes to the magnetic equator and acquires 

 large deviations on east and west headings only, this indicates a need for ad- 

 justment of the fore-and-aft magnets at that locality. 



PROBLEM 6 



The U. S. S. Whip was adjusted at New York, N. Y., and recorded the follow- 

 ing table of deviations for compass headings : 



The U. S. S. Whip had fore-and-aft magnets 

 red aft and athwartships magnets red 

 port, two 7 inch spheres athwartships 

 at 15 inches and 6 inches of Flinders bar 

 forward of the binnacle. 



On arrival at the Panama Canal Zone the U. S. S. Whip was swung for a 

 deviation curve w^ith the same corrector conditions and the following table of 

 deviations on compass headings was recorded : 



Analyze the above deviation curves and determine what coefficients should 

 be corrected at Panama. State what correctors you would adjust to correct 

 these coefficients; and, whenever possible, give the mcgnitude and direction of 

 these adjustments. 



639720—45 10 



