SPECIMEN EXAMINATION FOR THIRD MATE 



What index error is indicated by the 

 reading of the vernier on the microm- 



eter sextant shown below? 



Along what line is the value of micro- 

 seconds in miles the least; i.e., where 

 does the Loran reading give the great- 

 est positional accuracy? 



What is a clinometer? 



What is a "microsecond"? 



Make a rough copy of the sketch be- 

 low and indicate on it the ground wave, 

 first sky wave and second sky wave. 



jUI 



JL 



In using sky waves to obtain a Loran 

 line of position, what precaution is nec- 

 essary to insure that the complete wave 

 is being used? 



What care do you use in handling 

 glass sounding tubes? 



Give a brief description of the Radio 

 Direction Finder. 



Describe the use of parallel rules. 



What errors affect a radio bearing? 



When using the fathometer, suppose 

 three distinct flashes are registered on 

 the dial; by which one would you be 

 guided? 



How do you haul in a log line and 

 care for it while not in use? 



How would you determine whether 

 you are holding the sextant vertically 

 when taking a sight and making the 

 final adjustment of the tangent screw? 



What would be the effect on the alti- 

 tude if the sextant is not held vertically 

 when the sight is taken? 



In what position is the loop antenna 

 of a radio direction finder : 



(a) When the loudest signal is re- 

 ceived ; 



(b) When the minimum signal is 

 received ; 



(c) Which is used to obtain the 

 bearing and why? 



