This presentation is just a quick guide on how to solve the compass error by means of the sun in 2 methods, by the ABC method and the standard method

1. By: Gian Gabriel Ibo
Deck Cadet

2.  First you need the following information
 -Date
 -Time in UTC or GMT
 - Ships Posotion
 -Variation (can be found on charts and ECDIS)
 -Gyro course
 -Gyro Bearing
 -Magnetic Course

3.  Date: 22 July 1997
 Time: 15h 10m 20s (Philippine Local Time)
 Position: Latitude- 12° 00’N
 Longitude- 121° 30’ E
 Variation: 1.25’W
 Gyro Course: 270°
 Gyro Bearing: 286.1°
Magnetic Course: 265°

4.  1.) First is to get the GMT
 15h 10m 20s- Local Time (+8 time zone)
 08h 00m 00s(-)
 07h 10m 20s - GMT

5.  - Get the GHA by the use of the Nautical
Almanac
 - Get also the increments by the use of the
Nautical Amanac

8. You Have now your GHA and Increments
GHA= 283° 23.9’
INC= 2° 35.0’ + Always plus
GHA= 285° 58.9’
Long= 121° 58.9’E
LHA= 406° 88.9’ E
+1 -60
407° 28.9’
-360°
LHA= 47° 28.9’ W
E (+)
W (-)
-360 if LHA is over 360°

10. Get Declination
Dec= 20° 15.1’ N
0.1’ (-)
Dec= 20° 15.0’ N
d= 0.5 (bottom part
of the
declination
page)
Minus because Declination
Is Decreasing

11. Get the True Bearing
Tan Z=
Sin LHA
Tan Dec x Cos lat (+)(-) Cos LHA x sin Lat
(+) Different name
(-) Same name
Lat and Dec

12. tanZ=
Sin (47° 28.9)
Tan(20°15.0’)xcos(12°) – cos (47°28.9’)x sin(12°)
tanZ= (3.34) Z= tan-1(3.34)
Z= N 73.36 W
N
S
EW
-360 As is
+180 -180
360
Zn= 286.4°
LHA Declination

13. OR YOU CAN SOLVE IT BY USING
THE ABC METHOD

14. A= Tan Lat
Tan LHA
B= Tan Dec
Sin LHA
C= A(+,-)B
Change name of latitude
if LHA is not in range
between 90°-270°
Name of Declination
Z= Cx Cos lat= x
1/x= tan-1= Z

15. A= Tan 12°
Tan 47°28.9’
B= Tan 20°15
Sin LHA
C= A(+,-)B
Z= Cx Cos lat= x
1/x= tan-1= Z
=0.19S
=0.50N
=0.31N
0.31 x cos(12°)= 0.30
1/0.30= 3.33
Tan-1(3.33)= N73.36W
TB=286.4°

16. GB= 286.1°
TB= 286.4°(-)
GE= 0.3 E
GC=270°
TC= 270.3°
MC=265°
CE= 5.3E
Var= 1.4W (E)
Dev= 6.7 E
Remember the rule
Compass best Error (W)
Compass Least Error (E)
Change the name of the
Variation when solving for
The deviation

17. Checking:
C- 265°
D- 6.7°E
M- 271.7°
V- 1.4°W
T- 270.3°

18. Thank you and Godbless