SPECIMEN EXAMINATION FOR SECOND MATE 



39 



18. TIDES AND CURRENTS. 



Define: 



(a) Flood tide. 



(b) Ebbtide. 



(c) Set of tide. 



(d) Drift of tide. 



Where would you find the time of 

 slack water after high or low water in 

 any given port of the United States? 



What are subordinate stations, as 

 used in the Tide Tables? 



What is the purpose of the ratios 

 given in the Tide Tables for computing 

 height of tide and how would you use 

 such ratios? 



Name three planes of references to 

 which soundings and tidal data are re- 

 ferred. 



Describe the effect of wind and ab- 

 normal barometric conditions on the 

 tides. 



What celestial body is principally re- 

 sponsible for the tides, and what addi- 

 tional celestial body influences the tide? 



At St. Johns, New Brunswick on 7 

 February 1958: 



(a) What is the tabulated time 

 and height of a.m. high water? 



(b) If the largest scale chart of 

 the locality showed a depth of 10 feet 



for a given area, what would be the 

 depth at high water at that area? 

 At Anchorage, Alaska on 3 May 1958: 



(a) What is the tabulated time 

 and height of p.m. low water? 



(b) If your chart of Anchorage 

 showed a depth of 20 feet for a given 

 area, what would be the depth at low 

 water at this area? 



At Deer Island Light, Boston, Mass. 

 Harbor on 28 March 1958 : 



(a) What is the tabulated time 

 and velocity of maximum p.m. ebb cur- 

 rent? 



(b) In what direction does the ebb 

 current flow at this position? 



(c) What time meridian is used in 

 tabulating the times given for the 

 currents at this port? 



At San Diego Bay Entrance, Cali- 

 fornia on 13 January 1958: 



(a) What is the tabulated time 

 and velocity of maximum a.m. flood 

 current off" Ballast Point? 



(b) In what direction does the 

 flood current flow at this position? 



(c) What time meridian is used in 

 tabulating the times given for the cur- 

 rents at this port? 



19. OCEAN WINDS, WEATHER AND CURRENTS. 



How is the sea water temperature ob- 

 tained for a weather observation? 



How would you read a thermometer? 

 State the sources of possible error. 



How should a wet and dry bulb hy- 

 grometer be placed and what care 

 should be given to this instrument? 



Convert (— ) 10° Celsius (Centi- 

 grade) into temperature Fahrenheit. 



What is "sleet"? 



Define the tei-m "temperature". 



On a weather map : 



(a) An elongated area of high 

 pressure extending from an eminence 

 (or high) is called a ? 



(b) An elongated area of low pres- 

 sure extending from a depression (or 

 low) is called a ? 



What is "wave height"? 



What "wave height" should be re- 

 corded? 



How is the visibility determined? 



What is a "synoptic chart"? 



What is an "occluded front"? 



What is the meaning of the term "sky 

 cover" and how is the "sky cover" de- 



termined for purposes of weather re- 

 ports? 



What is meant by the cloud "ceil- 

 ing"? 



How would you determine the "cloud 

 ceiling"? 



What are the four principal families 

 or types of clouds, and what feature 

 forms the basis of the classification? 



Low clouds are defined as those whose 

 mean upper level is 6,500 feet. 



Middle clouds are defined as those 

 whose mean lower level is 6,500 feet and 

 whose mean upper level is 20,000 feet. 



High clouds are defined as those 

 whose mean lower level is 20,000 feet. 



Classify as low, middle, or high the 

 following cloud forms : 



(a) Altocumulus. 



(b) Cirrostratus. 



(c) Stratus. 



Why are islands or shore lines in the 

 tropics often marked by cumulus type 

 clouds in the daytime, particularly in 

 the afternoon ? 



