140 



HANDBOOK OF MAGNETIC COMPASS 



Answers Comment 



(4) True. Changing the correctors for the magnetic adjustment will necessitate 

 changing the degaussing compensation and a new curve must be 

 taken for both. Also, the normal curve is the basis of the de- 

 gaussing curve. 



False. Deperming does not affect the induced magnetism of a ship. 



True. Induction in the Flinders bar from the heeling magnet will change 

 as the heeling magnet is raised or lowered. 



True. The errors introduced by roll on north or south headings will be at 

 right angles to the earth's field and thus oscillations will be maxi- 

 mum on those headings. 



False. A Napier's diagram is used to obtain magnetic headings from com- 

 pass headings and vice versa. 



False. When swinging for the degaussing deviation curve the coils should 

 be set for the actual values as indicated by the range data. 



False. The coil polarity should be reversed and the regular procedure 

 followed. 



False. Secure degaussing by reversals to eliminate the residual effect. 



True. Deperming effects decay very rapidly the first few days, and it is 

 best to let the ship approach a stable state of magnetization before 

 adjusting. \ 



True. A red pole would be set up in the bow and this will cause a westerly 

 deviation on east and an easterly deviation on west. 



False. The same westerly error on all intercardinal headings does not 

 represent D error, hence do not use larger spheres. 



True. Due to the change in the heeling coil current, the induction in the 

 Flinders bar will change and the (B) coil will have to be read- 

 justed. 



False. Flinders bar corrects for induced effects in vertical soft iron. 



True. The poles of the ship would probably be in the port and starboard 

 sides of the ship and this would give maximum deviations with 

 the ship on north and south courses. 



False. Magnets should be fore-and-aft to correct B error. 



True. It is best to magnify the error at dockside in order to get finer 

 adjustment. 



False. More magnets further away will give a more symmetrical field at 

 the compass. 



False. Deperming removes only the permanent magnetism of the ship. 



True. The errors introduced by pitch on east or west will be at right an- 

 gles to the earth's field and thus will be maximum on those headings. 



False. Sphere correction effects are not constant for all latitudes because of 

 compass needle induction. Further, the Flinder bar, as a jS correc- 

 tor, changes D errors. 



False. The Flinders bar will have a blue end induced in the top after 

 crossing the magnetic equator to north latitude. 



False. Deviation will not change because the deviating force from hori- 

 zontal induction varies with the horizontal earth's field, the same as 

 the directive force. 

 (26) True. The heeling magnet compensates for vertical permanent and vertical 

 induced effects. 



