A.vessel's geographic position B.vessel's heading C.earth's magnetic field D.influence of the magnetic materials of the vessel
A.Flinders bar should be inverted B.Heeling magnet should be inverted C.The quadrantal spheres should be rotated 180° D.Flinders bar should be moved to the opposite side of the binnacle
A.used B.available C.in use D.can be used
A.permanent magnetism B.subpermanent magnetism C.induced magnetism D.variable magnetism