Quadrantal error in a gyrocompass has its GREATEST effect（）.

单项选择题Magnets are placed in horizontal trays in the compass binnacle to compensate for the（）.

A.induced magnetism in the vessel's horizontal soft iron
B.change in the magnetic field when the vessel inclines from vertical
C.permanent magnetism of the vessel
D.magnetic fields caused by electrical currents in the vicinity

单项选择题Magnetic variation changes with a change in（）.

A.the vessel's heading
B.sea conditions
C.seasons
D.the vessel's position

单项选择题Magnetic heading differs from compass heading by（）.

A.compass error
B.true heading
C.variation
D.deviation

单项选择题Magnetic dip is a measurement of the angle between the（）.

A.geographic pole and the magnetic pole
B.lubber's line and true north
C.horizontal and the magnetic line of force
D.compass heading and the magnetic heading

单项选择题Magnetic compass deviation（）.

A.varies depending upon the bearing used
B.is the angular difference between magnetic north and compass north
C.is published on the compass rose on most nautical charts
D.is the angular difference between geographic and magnetic meridians