航海英语磁罗经与陀螺罗经的使用章节练习(2018.01.30)

A.a collision with another vessel
B.being moored on a constant heading for a long period of time
C.being struck by lightning
D.All of the above

A.reduce the variation as much as possible
B.reduce the deviation as much as possible
C.reduce the magnetic dip as much as possible
D.allow the compass bowl to swing freely on its gimbals

A.variation
B.deviation
C.compass error
D.drift

A.compass north
B.the direction of the vessel's head
C.magnetic north
D.a relative bearing taken with an azimuth circle

A.Worn gears in the compass housing
B.Magnetism from the earth's magnetic field
C.Magnetism within the vessel
D.Lack of oil in the compass bearings

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

A.use the magnets one at a time，putting one in one side and then one on the opposite side，one step higher
B.use the magnets in pairs，starting at the top，with trays at the highest point of travel
C.use the magnets in pairs，from the bottom up，with the trays at the lowest point of travel
D.fill all the trays with magnets，then remove them one-by-one until the deviation is removed

A.worn gears in the compass housing
B.magnetism from the earth's magnetic field
C.magnetism within the vessel
D.lack of oil in the compass bearings

A.induced magnetism in vertical soft iron
B.induced magnetism in horizontal soft iron
C.permanent magnetism in ship's steel
D.vessel's inclination from the vertical

A.nonmagnetic
B.weatherproof
C.corrosion resistant
D.capable of being permanently affixed to the vessel