Find the true bearing of the lines with the following observed magnetic bearings and declinations.
(a) Bearing of line = N 45° 20′ E, Declination = 2° 15′ W
(b) Bearing of line = S 15 °25′ E, Declination = 1° 10′ E
Solutions :
(a) magnetic bearing of line= N 43° 20′ E
corresponding WCB= 43°20′
True bearing of line = magnetic bearing of line – Declination (west)
TB= 43°20′ -2°15′
= N 41°05’E
(b)
magnetic bearing of line= S 15°25′ E
corresponding WCB= 180° – Q B
= 180° -15°25′ = 164° 35′
True bearing of line = magnetic bearing of line + Declination (East)
TB= 164°35′ +1°10′
= 165°45 ‘
Reduced bearing of = 180′ -165°15’
= S 14°15 ‘E
Note:
True bearing = Magnetic bearing + Declination
(b) Declination East
[Use + sign when Declination’ East]
[Use – sign when Declination West]
Magnetic bearing = True bearing + Declination
[Use + sign when Declination West]
[Use – sign when Declination East]