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Case XVI 



TO SCOUT FROM INITIAL RELATIVE POSITION IN A GIVEN GENERAL DIRECTION AND RETURNING TO A 

 FINAL RELATIVE POSITION, SPEEDS AND TIMES ON BOTH LEGS BEING SPECIFIED 



GIVEN: COURSE AND SPEED OF GUIDE, INITIAL AND FINAL RELATIVE POSITION OF SCOUT, GEN- 

 ERAL DIRECTION OF FIRST COURSE, AND TIME AND SPEED OF SCOUT ON EACH LEG. 



TO DETERMINE: COURSES OF SCOUT AND RELATIVE POSITION AT TURNING POINT. 



Example. — Guide is on course 320°, speed 12.0 knots, with scout A now stationed 10.0 miles broad on the starboard 

 beam of the Guide. A is ordered to scout in a northerly direction, using a speed of 20.0 knots for 4 hours and a speed of 

 15.0 knots for 4 hours. At the end of the 8 hours, A must reach its new station, 10.0 miles on the starboard quarter of the 

 Guide, ready to assume course and speed of the Guide. 



Required. — (a) Course of A on first leg. (b) Course of A on second leg. (c) Relative position of A from the Guide at 

 turning point. (See fig. 20.) 



Procedure. — Since the Guide is on a steady course for 8 hours and the distances are fixed that A must travel on each 

 leg, it is readily apparent that regular chart work, or the Navigational Plot, is indicated. 



Plot the initial position of the Guide and of A at Gx and A t respectively. Advance the position of the Guide to G 2 for the 

 run of 8 hours or 96.0 miles on course 320°. Locate A 2 , the position of the scout at the end of 8 hours. 



With Ai as a center, draw a circle with radius of 80.0 miles, the distance covered by the scout on the first leg. Similarly, 

 with A 2 as a center, draw a circle with radius of 60.0 miles. These circles intersect at K and K! . By the conditions of the 

 problem A is to scout in a northerly direction, so A x .... K represents the course on the first leg and K . . . . A 2 the course 

 on the second leg. 



To find the relative position of A at the turning point, locate G', the position of the Guide at the end of 4 hours. G' . . . . K 

 represents the bearing and distance of A from the Guide. 



Answer.— (a) 359°. (b) 257°. (c) 62.5 miles bearing 037° from the Guide. 



NOTE. — In case the initial course for A had been specified instead of the initial speed, this course would have been laid out from A\, inter- 

 secting the circle about Ai at X and X' . The courses for the second leg, in this case, would be X .... At or X' ... . A 2 , depending upon 



whether the speed indicated by A\ 





X divided by 4 hours or A\ 



X' divided by 4 hours is used. 















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