SPECIMEN EXAMINATION FOR MASTER 



85 



13. SPEED BY REVOLUTIONS. 



If the engine speed necessary to 

 reach port at a designated time is 12.6 

 knots and the pitch of the wheel is 13.6 



feet, how many revolutions per minute 

 would have to be turned up ? 



14. FUEL CONSERVATION. 



While turning up 90 revolutions per 

 minute, a steamer consumes 8 barrels 

 of fuel oil per hour. If it is determined 

 that only 7 barrels of fuel per hour is 

 available to reach port, how many 

 revolutions per minute shall the engines 

 turn? 



A vessel has sufficient fuel to steam 

 760 miles at her normal speed of 11 

 knots. If she has 915 miles yet to run on 

 the same amount of fuel, what speed 



must she reduce to? 



A vessel has a trip 4,010 miles to 

 make and leaves port with 1,010 tons of 

 fuel. After running 2,500 miles at her 

 normal speed of 14 knots, the engineer 

 reports he has only 270 tons of fuel re- 

 maining. At what reduced speed must 

 you steam in order to reach your 

 destination with 20 tons of fuel remain- 

 ing? 



15. INSTRUMENTS AND ACCESSORIES. 



Where, in the area covered by a pair 

 of loran stations, may the most accurate 

 lines of position be obtained? 



Where, in the area covered by a pair 

 of loran stations, are the least accurate 

 lines of positions available? 



Why is loran known as a "hyperbolic" 

 system of navigation? 



Within what distance from the trans- 

 mitting station is the use of skywaves 



not to be relied on for obtaining a loran 

 line of i)osition? 



When a first sky wave and ground 

 wave are matched, what precautions 

 must be observed to obtain a line of 

 position? 



Describe how the deviation of a radio 

 direction finder is determined and how 

 it is compensated. 



16. MAGNETISM, DEVIATION AND COMPASS 



If the easterly deviation increases on 

 westerly headings as the vessel steams 

 north, what adjustment should be made 

 in the Flinders Bar? 



How would you correct westerly 

 quadrantal deviation on a SW heading? 



Does the heeling magnet, once ad- 

 justed, require change as the vessel 

 sails from one magnetic latitude into 

 another? Explain your answer. 



If your compass card appears to be 

 magnetically "frozen" on a heading of 

 090° on all headings of the vessel, how 

 would you adjust to correct this condi- 

 tion? 



How would you detect and correct re- 

 tained magnetism in the soft iron 

 spheres? 



Discuss the effects on the deviation of 

 a compass when a vessel stays on one 

 course for several days, particularly in 

 rough seas, or lays at a dock on one 

 heading for a lengthy period, or fails 

 to follow a reversal sequence in secur- 

 ing the degaussing equipment. 



COMPENSATION. 



How would you test a magnetic com- 

 pass for sensitivity? 



How would you detect and correct re- 

 tained magnetism in the Flinders Bar? 



What sources of magnetism other 

 than the vertical induction from the 

 earth's field may influence the action of 

 the Flinders Bar? 



Given a compass and its Flinders Bar 

 corrector arranged in alternate posi- 

 tions as sketched. In which position will 

 the Flinders Bar exert the greatest 

 effect on the compass. Why? 



I 



