86 



UNITED STATES COAST GUARD 



If a heeling adjuster or vertical force 

 instrument is not available, how would 

 you place the heeling magnet when ad- 

 justing the compass? 



How would you correct your compass 

 for an easterly error due to permanent 

 magnetism when the vessel is on an 

 easterly heading? 



17. CHART CONSTRUCTION. 



Construct a small area plotting sheet 

 for 59 degrees to 61 degrees North 

 Latitude, allowing 3 inches for each de- 

 gree of latitude. 



Construct a Mercator chart, or a 

 small area plotting sheet, for Latitudes 



35 degrees North to 37 degrees North 

 and Longitudes 157 degrees 30 minutes 

 East to 158 degrrees 30 minutes East. 

 Use a scale of 2% inches to 1 degree of 

 longitude and label latitude and longi- 

 tude properly. 



18. TIDES AND CURRENTS. 



At South End Woods Hole, Vineyard 

 Sound-Buzzards Bay, (Latitude 41°- 

 31' North and Longitude 70''-40' West) : 



(a) What is the time and velocity 

 of maximum AM flood current on 5 

 January 1958? 



(b) In what direction does the flood 

 current flow at this point and what is 

 the average velocity? 



At Grindstone Island, Petitcodiac 

 River, New Brunswick, Bay of Fundy; 



(a) What is the time and height 

 of a.m. high water on 6 April 1958? 



(b) What is the mean range of 

 tides for this locality? 



(c) What is the spring range of 

 tides for this locality? 



(d) What is the range of a.m. tides 

 for this locality on 6 April 1958? 



(e) What peculiar tidal phenomena 

 may mariners encounter in this area? 



East of the Statue of Liberty in 

 Upper Bay of New York: 



(a) Determine the time of a.m. 

 slack high water on 10 April 1958. 



(b) What is the duration of slack 

 water when a current less than 0.1 knot 

 can be expected? 



State what is meant by the diurnal 

 inequality of the tides, and describe the 

 reasons why this phenomenon occurs. 



Describe what is meant by a "bore." 



What is meant by the term: "high 

 water lunitidal interval," "establisn- 

 ment of the port," and "vulgar estab- 

 lishment"? 



Define : 



(a) The mean range of the tide. 



(b) The spring range of the tide. 



(c) The diurnal range of the tide. 



Referring to the Current Diagram in 

 the Atlantic Coast Current Tables, de- 

 termine the time interval within which 

 a 10 knot vessel should pass Overfalls 

 L/V in order to go upstream with flood 

 current to Chestnut Street, Philadelphia 

 on the morning of 16 November 1958. 



If, at the same time, a tidal current 

 is setting north at 1.0 knot, and a wind 

 driven current is setting east at 1.0 

 knot, what is the resultant direction and 

 velocity of current that may be expected 

 from the combination of the two cur- 

 rents? 



19. OCEAN WINDS, WEATHER AND CURRENTS. 



Can a wet bulb thermometer ever 

 properly read higher than a dry bulb? 



How may the wet bulb temperature 

 be determined in freezing weather? 



Convert 20° Celsius (Centigrade) into 

 the temperature Fahrenheit. 



Name three corrections that must be 

 applied to readings of the mercurial 

 barometer, and explain why each cor- 

 rection is required. 



How should a barometer be installed? 



Give the factors that should be con- 

 sidered in determining a proper loca- 

 tion for this instrument. 



What is an "isallobar"? 



If a surface temperature is 90° F. 

 and the wet adiabatic, or pseudo-adiaba- 

 tic, lapse rate is 1° F. for each 300 feet, 

 what is the temperature of cirrus-t>T)e 

 clouds at "21,000 feet altitude? In what 

 form would the water vapor be present 

 in such clouds? 



