TO INSURE PASSING OUTSIDE OF A SPECIFIED RANGE FROM THE GUIDE WITH A COLUMN OF SHIPS, USING 



HEAD OF COLUMN CHANGE OF COURSE 



Example B. — The leading vessel and flagship of a Cruiser Division of 3 ships in column formation, with a distance o 

 1,000 yards between vessels, is on Fleet Course of 139° at Fleet Speed 10.0 knots. Cruiser Flagship, now stationed 8,000 yard- 

 broad on the port bow of the Fleet Guide, receives orders to proceed with the division to new station 8,000 yards on the stars 

 board quarter of the Fleet Guide, keeping clear of the antisubmarine screen en route. The Cruiser Division Commander 

 decides to use 20.0 knots, to allow 3,000 yards radius for the screen, and to make the change to new station by column move- 

 ments, passing ahead of the Guide. 



Required. — (a) Course to cross ahead of the Guide, (b) Course to final station after clearing Guide, (c) Range and 

 bearing of Fleet Guide from Cruiser Flagship when course is changed as in (b). (See fig. 9.) 



Procedure. — Plot Fleet Guide at G. Plot initial positions of the cruisers at CF, CA, and CB, CF being the Cruiser 

 Flagship, and final position of CF at CF' . 



Draw Guide's vector e . . . . g. 



Advance G along the Fleet Course the distance it would run while CB at 20.0 knots in advancing to the point where CF 



Speed of G 10.0 



changed to the first course. This distance is equal to . __ X 2,000 yards or — ~X2,000 yards=l,000 yards. This is 



done because in any column movement speed changes are made simultaneously while course changes are made in succession. 

 About the advanced Guide's position G' draw a circle with radius equal to 3,000 yards, enclosing the antisubmarine area. 



From CF draw a tangent to this circle. From CF' draw a second tangent to this offset circle, intersecting the first tangent 

 at X. CF . . . . X represents the Relative Movement of the Cruiser Flagship in respect to the Guide while on the first 

 leg. X . . . . CF' represents similarly the Relative Movement while on the second leg. The bearing and distance of the 

 Guide from CF at the turning point for starting the second leg is represented by X .... G. 



Transfer slopes CF . . . . X and X . . . . CF' to g, intersecting the 20.0-knot speed circle at Ci and c 2 respectively. 

 The vector of the first leg is e .... Ci and of the second leg is e .... c 2 . 



Answer.— (a) 211 1 / 2 °- (b) 285°. (c) Range 4,200 yards, bearing 348°. 



NOTE. — This particular example is included to emphasize the fact that a column of ships may occupy considerable space. When maneuvering 

 in the vicinity of other formations and units, all course and speed changes planned should take this entire space into consideration. Should the 

 total length of the column be neglected, vessels following the column leader may be compelled to take an echelon formation to keep out of the 

 danger area. This further reacts to increase the speed required to resume proper station in column, with consequent increase in fuel consumption. 



The path CB .... CA .... F ... . CB'", etc., indicates the Relative Movement of the last vessel in the column 

 with respect to the Guide. While CB is advancing to the turning point for CF, its vector is indicated by e . . . . cb, and its 

 speed relative to the Guide is £ . . . . cb, or 10.0 knots. Using the Logarithmic Scale and the 3 minutes required for this 

 advance, it is found that CB advances 1,000 yards relative to G, making it occupy the original relative position of CA, the 

 second ship in column. From this point, its movement relative to G is indicated by the slope CA . . . . Y, which passes 

 outside of the 3,000-yard antisubmarine screen circle about G. 



The Cruiser Flagship, as shown by its Relative Movement Lines CF . ... X ... . CF', passes well outside of this 

 3,000-yard circle, but the extra distance travelled has prevented the embarrassing of the other ships in column and maintained 

 better concentration. 



The positions occupied by the three ships on the first and second legs for any moment are shown by CF" , CA" , and 

 CB" and by CF'", CA'", and CB'" respectively. 



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