CHAPTER IV. TYPICAL DEVIATION CURVE AND THE 

 ESTIMATION OF APPROXIMATE COEFFICIENTS 



38. Simple analysis. — The data for the deviation curve illustrated 

 in figure 21 is as follows : 



Ship's compass heading : 



Deviation 



N. (000°) 10.5° E. 



NE. (045°) 20.0° E. 



E. (090°) 11.5° E. 



SE. (135°) 1.2° W. 



S. (180°) 5.5° W. 



SW. (225°) 8.0° W. 



W. (270°) 12.5° W. 



NW. (315°) - 6.8° W. 



Since A is the coejQBcient of constant deviation, its approximate value 

 is obtained from the above data by estimating the mean of the alge- 

 braic sum of all the deviations. Throughout these computations the 

 sign of east deviation is considered plios, and west deviation is con- 

 sidered minus. 



Mfsreet/ 



Dbv ^ a ->■ a 5//tf 4 -^C Coi> 4 *■ D SiN 2 4 +E: Cos e i 



Typicni. De-viaTiom Cut 



.& IT^ 



lr^oi\^/oufiL Cof^PoNe-Nr& 



Figure 21. 



8 J.= + 10.5° +20.0° + 11.5^ -1.2° -5.5° -8.0° -12.5° -6.8* 

 8 ^ = +42.0° -34.0° = +8.0° 

 ^--+8.0°/8= + 1.0° = 1.0° E. 



29 



