66 



HANDBOOK OF MAGNETIC COMPASS 



bar is present at the time of calculations, it must be remembered 

 that it is already correcting an amount of c in the ship (see figure 

 34 (b) ) which must be added to the uncorrected c, calculated by 

 the above formula. This total value of c, is used in conjunction 

 with figure 34 (b) to indicate directly the necessary total amount 

 of Flinders bar. If this total c is negative, Flinders bar is re- 

 quired on the forward side of the binnacle; and if it is positive, 

 Flinders bar is required on the aft side of the binnacle. The iron 



DBGRetr> cpeetcT/oN ^ 



LBNGTH OP BAB 



Note! Flinders bar not shimmed away from 

 binnacle for Heeling Coll. When shimmed, 

 this data is only 90^ effective. 



DIF' ' DE-VIATIONCUeV£i. 

 FOB FLINOeeS ) e>Fil3 



Figure 34. 



• sections of Flinders bar should be continuous and at the toy of 

 the tube with the longest section at the top. Wooden spacers 

 are used at the bottom of the tube to achieve such spacing. See 

 problem 6 in the appendix for solution of a typical problem. 

 It will be noted that the B deviations used in this formula are 

 based on data on E./W. magnetic headings rather than on com- 

 pass headings, as with the approximate coefficients. The Napier's 

 diagram will assist in conversion of data from compass headings 

 to magnetic headings, if necessary. 



