SPECIMEN EXAMINATION FOR CHIEF MA^E 



65 



Entering from seaward you sight the 

 black and red horizontal band buoy 

 shown. 



(a) Which side is best to leave it 

 on in passing? 



(b) What number would you ex- 

 pect it to have? 



(c) What color light would you ex- 

 pect it to show? 



(d) What light phase characteris- 

 tic would it likely have? 



(e) Sketch the chart symbol for 

 the buoy. 



A buoy painted yellow and red as 

 illustrated is used in what system of 

 navigational aids? 



YELLOW 



RED 



13. SPEED BY REVOLUTIONS. 



Propeller pitch 17.7 feet, revolutions 

 per day 81,630, calculate the day's run 



allowing 6 percent slip. 



15. INSTRUMENTS AND ACCESSORIES. 



Do Loran sky wave corrections repre- 

 sent the exact amount of correction 

 necessary or are they merely average 

 correction values? Explain. 



Are Loran sky waves as reliable and 

 accurate for navigational purposes as 

 ground waves? 



What precautions must be borne in 

 mind in celestial navigation or piloting, 

 when the navigator uses lines of posi- 

 tion that cross at small angles? 



Where is the most unfavorable area 



for obtaining a line of position from a 

 pair of Loran transmitters? 



Describe the factors which influence 

 the accuracy of a fix obtained by using 

 Loran lines of position. 



Explain briefly how the 180° ambi- 

 guity in radio direction finder bearings 

 may be resolved. 



If a ship's radio direction finder is 

 fitted with a quadrantal error compen- 

 sator, will it be affected by changes 

 made in the set or its surroundings? 



