SPECIMEN EXAMINATION FOR THIRD MATE 



Describe briefly the use of aeronauti- 

 cal radio ranges for surface navigation. 

 What signal is emitted by such sta- 

 tions? 



How would you check the calibration 

 for a radio direction finder? 



Why is it desirable that a ship's 

 radio direction finder set be capable of 

 receiving signals between 275 and 515 

 kilocycles? 



What publications give information 

 about stations which may be employed 

 by the navigator in determining posi- 

 tion by radio? 



How are Sailing Directions cor- 

 rected? 



Of what use are Notices to Mariners 

 in correcting charts? 



How often are the Notices to Mar- 

 iners published? 



A vessel is on course 045° at a speed 

 of 10 knots. What is her departure each 

 hour? If the vessel is at Latitude 45°, 

 what is her hourly change of longitude? 



A vessel is on a course of 060° at 

 a speed of 20 knots. How much does 

 she change her latitude each hour? 



How would you obtain a radio bear- 

 ing, when the minimum, or null, is not 

 well defined? 



In picking up a light, what advan- 

 tage might you gain by going on to 

 the upper bridge, or posting the look- 

 out aloft? 



Running coastwise, you sight a buoy 

 bearing 10° on the starboard bow. The 

 buoy marks a dangerous shoal to the 

 right of the buoy with safe water to 

 the left. If, after an interval, the buoy 

 bears 6° on the starboard bow, what 

 would be indicated? What action would 

 you take? 



How may vessels in distress enable 

 ships and radio direction finder stations 

 to take radio bearings? 



Describe the effect of electrical con- 

 ductors near the radio direction finder. 



A radio beacon is 6° east of your 

 vessel in Latitude 45° North. State the 

 amount and direction to correct a bear- 

 ing for plotting on a Mercator chart. 



From Latitude 60° South and Longi- 

 tude 150° East to Latitude 60° South 

 and Longitude 150° West, determine 

 the distance by parallel sailing. 



A vessel's noon position by observa- 

 tion is Latitude 40°-02' South and 

 Longitude 15°-09' West. Her dead reck- 

 oning position advanced from the pre- 

 vious noon position is Latitude 40°-20' 

 South and Longitude 15°-09' West. 

 Required: The set and drift of the 

 current for the previous 24 hours.^ 



You sight a mountain peak just 

 breaking clear over the horizon. If the 

 chart lists the height of the mountain 



as 720 feet and your height of eye is 

 45 feet, what is your distance off? 



Give the meaning of the following 

 symbols as shown on a chart: 



(a) 



(b) 



CO 



^ 4. ^ ^ 



State the meaning of the following 

 abbreviations used on charts to indicate 

 bottom characteristics : 



State the characteristics of Deer 

 Island Light in Boston Harbor for 

 which the light list gives the following 

 information : 



F. W., Alt. Fl., R., 30 sec, R. sector. 



What precaution is necessary if you 

 use a pilot chart to determine variation? 



How are ocean currents and their 

 drift indicated on pilot charts? 



Describe plotting sheets and their 

 use. 



On a vessel outward bound, range 

 lights are seen in line over the stern. 

 If the ship is on gyro-compass head- 

 ing 150°. 5, what is the gyro-compass 

 error, if the chart shows the range 

 line to be 331 °-30' true? 



On what part of a Mercator chart 

 do you : 



(a) Find the longitude scale; 



(b) Find the latitude scale; 



(c) Measure distance? 



How would one know whether the fig- 

 ures on charts indicating depths mean 

 fathoms, feet and fathoms, or feet? 



Do the figures shown on Atlantic 

 Coast charts indicate depths at high or 

 low water? 



What is the length of a statute mile? 



How is variation indicated on a 

 chart? 



