SPECIMEN EXAMINATION FOR CHIEF MATE 



63 



A ship "X" checks her position using 

 a sextant to determine angles "D" and 

 "E" between points "A" and "B," and 

 "B" and "C" respectively. How accurate 

 would you consider the position thus 

 determined when plotted with a three 

 arm protractor? 



State three methods by which, with- 

 out obtaining the precise position, the 

 navigator may assure himself that he is 

 clear of any particular danger. 



How would you determine your posi- 

 tion by a chain of soundings? 



State what navigational aids are in- 

 dicated by the symbols below. 



A vessel with a speed of 10 knots is 

 proceeding through a current setting 

 NE true with a drift of 6 knots. 



(a) What course should be steered 

 to make good a course of NW true? 



(b) What speed will the vessel 

 make on this course? 



Two vessels are in Latitude 50° 

 North. They are 400 miles apart when 

 they obtain radio direction finder bear- 

 ings of each other. 



(a) Would they bear east or west 

 from each other precisely on the uncor- 

 rected radio bearing? 



(b) Would the bearings of one 

 differ from the other by precisely 180°? 



Sketched is a marine type radio di- 

 rection finder loop antenna. Why is it 

 important that the insulator and gasket 

 noted by "A" be kept in good condition 

 and clean from paint and other mate- 

 rial? 



Would you use Mercator sailing or 

 Middle Latitude Sailing for a distance 

 of 600 miles or more? Explain your 

 answer. 



What accuracy can be expected nor- 

 mally with bearings furnished by shore 

 radio direction finder stations? 



How would you regard bearings by 

 shore radio direction finder stations 

 which were described, as doubtful, ap- 

 proximate or second class? 



For courses near 090° or 270°, why 

 is the use of the Mercator sailing 

 formulas not normally desirable? 



When is great circle sailing most ad- 

 vantageous? 



