The compass heading of a vessel differs from the true heading by（）.

单项选择题The compass error of a magnetic compass that has no deviation is（）.

A.zero
B.equal to variation
C.eliminated by adjusting the compass
D.constant at any geographical location

单项选择题The compass deviation changes as the vessel changes（）.

A.geographical position
B.speed
C.heading
D.longitude

单项选择题Quadrantal error in a gyrocompass has its GREATEST effect（）.

A.in high latitudes
B.near the equator
C.on north or south headings
D.on intercardinal headings

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