SPECIMEN EXAMINATION FOR THIRD MATE 



12. AIDS TO NAVIGATION. 



When a buoy marks the starboard 

 side of a channel for a vessel entering 

 port, state : 



(a) The shape of the buoy; 



(b) The color of the buoy; 



(c) The type of number on the 

 buoy; 



(d) The color of its light. 



Define exactly what is meant by an 

 occulting light. (Candidates may sub- 

 mit a sketch such as those contained 

 in the light lists to help demonstrate 

 complete comprehension of the term.) 



What is meant by the "Period" of a 

 light as listed in the light list? 



What height of eye on the part of 

 the observer is assumed in calculating 

 the geographic ranges of lights for 

 charts and light lists? 



What significance have buoys which 

 are fitted with a light which shows not 

 less than 60 flashes per minute? 



Define exactly what is meant by a 

 quick flashing light. (Candidates may 

 submit a sketch such as that contained 

 in the light list to help demonstrate 

 their complete comprehension of the 

 term.) 



Name the types of buoys sketched 

 below and sketch the chart symbol for 

 each. 



I Ked\ 



lateral system of buoyage of the United 

 States? 



A vessel hears the radio distance 

 finding signal from a light vessel and 

 5 seconds later hears the corresponding 

 sound signal. What is her distance from 

 the light vessel? 



How are the buoys numbered in the 

 United States lateral system of buoy- 

 age? 



(a) What color would the buoy il- 

 lustrated be painted? 



(b) What sort of number would be 

 assigned such a buoy? 



(c) How should such a buoy be 

 left in passing when entering from sea- 

 ward? 



(d) How is such a buoy shown on 

 a chart? Sketch chart marking for such 

 a buoy. 



What system is followed in assign- 

 ing colors to the lights of buoys in the 



On a clear night, how could you de- 

 teiTnine whether a navigational light is 

 at its maximum geographic range of 

 visibility when you first sight it? 



15. INSTRUMENTS AND ACCESSORIES. 



What is the purpose of the liquid 

 used in the magnetic compass? 



Give a brief description of the gyro- 

 compass. 



What is a Pelorus? 



Describe the Azimuth Circle. 



How often should a chronometer be 

 wound? 



How are ship barometers checked for 

 accuracy? 



What is a chronometer used for? 



Define the daily rate of a chronom- 

 eter. 



Describe the Aneroid barometer. 



In a heavy sea, the gyro alarm unit 

 in the wheelhouse sounds. What would 

 you do? 



What pi'operties of the earth make 

 the gyi'o-compass a meridian seeking 

 device? 



What three forms of steering are 

 available on a vessel equipped with a 

 gyro pilot or iron mike? 



In what direction does the axle of a 

 gyro-compass wheel point? 



