62 



Given : 



UNITED STATES COAST GUARD 



No.t 

 Mars 



Date 26 April 1958 



GMT 05h-38m-27s 



Long. 16°-23'.0 West 



Required : The meridian angle and 

 declination of the planet in each of 

 the 3 cases. Indicate whether the planet 



is east or west of the meridian in each 



case. 



4. STAR IDENTIFICATION (any method). 



On 20 January 1956, at Latitude 7"- 

 09' South, Longitude 112°-15' West, a 

 morning star observation is taken at 

 12h-48m-39s GMT of a star whose cor- 

 rected altitude is 40°38'.2, and whose 



azimuth is 118°. 9 True. 



Required: The name of the star. 



Candidates may use any method of 

 solution. Show all work. 



5. CHART NAVIGATION. 



How does a great circle course appear 

 on a polyconic chart? 



How are the latitude and longitude of 

 a point found on a gnomonic chart? 



How is the true bearing determined 

 between any two points on a large scale 

 polyconic chart? 



How is the distance measured on a 

 polyconic chart? 



Describe the usual method for using 

 a gnomonic chart to determine the great 

 circle course for a ship. 



Can any chart representation of the 

 earth's surface preserve all of the fol- 

 lowing properties : 



(a) The true shape of physical 

 features. 



(b) Correct angular relationships. 



(c) Equal areas, or the representa- 

 tion of areas in their correct relative 

 proportions. 



(d) True scale values for measur- 

 ing distances. 



(e) The representation of great 



circles as straight lines. 



(f) The representation of rhumb 

 lines as straight lines. 



What is the principal feature of Mer- 

 cator projection charts that makes them 

 desirable for marine navigational use? 



Does a Mercator projection chart cor- 

 rectly picture the shape of an area? 

 Explain your answer. 



Are all charts oriented so that north 

 is shown at the top of the sheet? Ex- 

 plain your answer. 



State in detail how you would make 

 use of depth curves on nautical charts 

 to assist you in fixing your position. 



What is meant by the figures 1:200,- 

 000 on a chart? 



For what type navigation would a 

 chart with 1:200,000 on it be suitable? 



Convert 7% meters into feet. 



State the purpose and describe the 

 use of hachures on charts. 



What is the length of a nautical 

 mile? 



