SPECIMEN EXAMINATION FOR MASTER 



87 



What are the factors that determine 

 the stability characteristics of a body 

 of air? 



When is a body of air known as un- 

 stable? 



When is a body of air knoAvn as 

 stable? 



Does the greatest vertical develop- 

 ment of cumulonimbus clouds occur in 

 the tropics or in high latitudes? Explain 

 the reason for your answer. 



Define the following types of New 

 Ice: 



(a) Ice-crystals (Frazil crystals). 



(b) Slush (sludge). 



(c) Pancake ice. 



(d) Ice-rind. 



When is the ice coverage at a mini- 

 mum in Arctic waters? 



A powered vessel can traverse ice 

 covering up to what proportion of the 

 sea surface without ice breaker assist- 

 ance? 



What consideration must be given to 

 draft when a vessel is to operate in ice? 



In operating in ice, what precautions 

 must be observed with respect to speed? 

 If necessary to strike the ice, what part 

 of the ship should encounter the blow? 



Operating a vessel in ice, where could 

 extra lookouts be stationed to help avert 

 propeller damage? Why is an immedi- 

 ate stop shaft order necessary when ice 

 appears near the propeller? 



What precautions must be observed 

 when anchoring in ice? 



When it is necessary to back down 

 in ice, how should the rudder be handled 

 for maximum protection from damage? 



In order that other vessels may be ap- 

 prised, what obligation is imposed by 

 the 1948 Convention for the Safety of 

 Life at Sea upon every shipmaster who 

 encounters dangerous ice at sea? 



What precaution, with respect to 

 speed, is imposed by the 1948 Conven- 

 tion for Safety of Life at Sea upon the 

 master of every ship when ice is re- 

 ported on or near his course? 



What duty is imposed by the Interna- 

 tional Convention for the Safety of 

 Life at Sea, 1948, on the master of 

 every vessel who encounters a tropical 

 storm? 



After a vessel has transmitted a 



warning of a dangerous storm, what 

 subsequent transmissions are desirable? 



What publication, containing infor- 

 mation of the storm advisory services 

 from whom weather information may be 

 obtained by radio, is required to be 

 carried by U.S. Merchant Vessels? 



Why does wind at 2,000 or 3,000 feet 

 above sea level blow nearly parallel to 

 the isobars, whereas the wind at sea 

 level is inclined toward the low pressure 

 area? 



What is the effect of a decrease in 

 the depth of the water on storm waves 

 rolling in from the open sea? 



Describe synoptic conditions that are 

 associated with origin of tropical cy- 

 clones. 



How may merchant vessels obtain an 

 analysis of the weather map, showing 

 pressure centers and fronts, when no 

 facsimile equipment or teletype is 

 aboard? 



Explain how mountainous terrain ad- 

 jacent to the seacoast can cause strong 

 local winds of gale force. 



How may the probability of en- 

 countering gales on an ocean passage 

 for a given period of time be deter- 

 mined? 



The maximum height of storm waves 

 can be approximated by the formula: 



H = 1.5 V F where: 



H is the height in feet and 



F is fetch in nautical miles. 



Using this formula, determine the maxi- 

 mum height of storm waves that may 

 be encountered when a gale is blowing 

 from a direction in which the coastline 

 is distant 400 miles. 



Swells from ocean waves generated 

 by storms move at a velocity ^ that of 

 the individual waves. If the individual 

 waves move at a speed of 40 knots, how 

 long would it take the swell to reach the 

 observer 400 miles away? 



In which semicircle of a tropical cy- 

 clone would a vessel be if the wind 

 shifted clockwise while the vessel was 

 hove to in the Southern Hemisphere? 



In the Southern Hemisphere, how 

 would a steam vessel maneuver in the 

 dangerous semicircle of a tropical cy- 

 clone? 



