航海英语(甲类船长)航海仪器单选题练习1
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Which magnetic compass corrector（s）can be set while the vessel is on a heading of magnetic north or magnetic south ________．
- A.Quadrantal spheres
- B.Heeling magnets
- C.Flinders bar
- D.Fore-and-aft magnets
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Which compensates for errors introduced when the vessel heels over ________．
- A.The soft iron spheres on the arms of the binnacle
- B.Magnets placed in trays inside the binnacle
- C.A single vertical magnet beneath the compass
- D.The Flinders bar
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When relieving the helm，the new helmsman should know the ______．
- A.Course per magnetic steering compass
- B.Gyro error
- C.Variation
- D.Maximum rudder angle previously used
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When a vessel changes course from one cardinal heading to another cardinal heading while adjusting the compass，which action should be taken ________．
- A.The course change should be made rapidly to prevent transient induced magnetism while passing the intercardinal headings
- B.After the new heading is reached，the vessel should steam on that course for at least two minutes before the adjustment
- C.During the course change，you should gently tap the compass to remove any error caused by friction on the pivot bearing
- D.After steadying on the new heading，the compass card should be slewed by a magnet and allowed to oscillate freely to remove any gaussin error
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When crossing the magnetic equator the ______．
- 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
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This induced magnetism ______ the permanent magnetism already present in the ship．
- A.will add to
- B.will subtract from
- C.may add to or subtract from
- D.will not change
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What is used to correct for both induced and permanent magnetism，and consequently must be readjusted with radical changes in latitude ________．
- A.Flinders bar
- B.Soft iron spheres
- C.Fore-and-aft permanent magnets in their trays
- D.Heeling magnet
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The most accurate method of determining gyrocompass error while underway is by ______．
- A.Comparing the gyro azimuth of a celestial body with the computed azimuth of the body
- B.Comparing the gyro heading with the magnetic compass heading
- C.Determining from the chart the course made good between celestial fixes
- D.It cannot be determined accurately at sea due to drift of unknown currents
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The gyrocompass error resulting from your vessel's movement in OTHER than an east-west direction is called ______．
- A.Damping error
- B.Ballistic deflection
- C.Quadrantal error
- D.Speed error
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The magnetism in the various structures of a ship changing as a result of cruising，vibration，or aging is termed ______．
- A.permanent magnetism
- B.subpermanent magnetism
- C.induced magnetism
- D.variable magnetism
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The error in a magnetic compass caused by the vessel's magnetism is called ______．
- A.Variation
- B.Deviation
- C.Compass error
- D.Bearing error
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The Flinders bar and the quadrantal spheres should be tested for permanent magnetism at what interval ________．
- A.They are not subject to permanent magnetism; no check is necessary
- B.Semiannually
- C.Annually
- D.Every five years
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Any piece of metal on becoming magnetized will develop regions of concentrated magnetism called ______．
- A.flux
- B.poles
- C.magnets
- D.azimuth
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A vessel is heading magnetic northwest and its magnetic compass indicates a heading of 312°．What action should be taken to remove this error during compass adjustment ________．
- A.If the quadrantal spheres are all the way out，replace them with smaller spheres
- B.If the quadrantal spheres are all the way in，replace them with larger spheres
- C.If the quadrantal spheres are all of the way out，move the spheres in
- D.If the quadrantal spheres are all the way out，replace them with larger spheres
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A ship under construction or major repair will acquire permanent magnetism due to ______ while sitting stationary in the earth's magnetic field．
- A.hammering and jarring
- B.vibration and pounding
- C.varying magnetic fields
- D.stable or permanent magnetism of the ship
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our radar displays your ship off center．As you proceed on your course，your ship's marker moves on the PPI scope while echoes from land masses remain stationary．What is this display called ________．
- A.Off center
- B.True motion
- C.Stabilized
- D.Head up
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Your radar is set on a true motion display．Which of the following will NOT appear to move across the PPI scope ________．
- A.Echoes from a buoy
- B.Own ship's marker
- C.Echo from a ship on the same course at the same speed
- D.Echo from a ship on a reciprocal course at the same speed
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Your ARPA has two guard zones．What is the purpose of the inner guard zone ________．
- A.Alert the watch officer that a vessel is approaching the preset CPA limit
- B.Warn of small targets that are initially detected closer than the outer guard zone
- C.Guard against target loss during critical maneuvering situations
- D.Sound an alarm for targets first detected within the zone
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Your ARPA has automatic speed inputs from the log．Due to currents，the log is indicating a faster speed than the speed over the ground．What should you expect under these circumstances ________．
- A.The generated CPA will be less than the actual CPA
- B.The generated TCPA will be later than the actual TCPA
- C.The range of initial target acquisition will be less than normal
- D.The targets true course vector will be in error
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Your ARPA has been tracking a target and has generated the targets course and speed．The radar did not receive a target echo on its last two scans due to the weather．What should you expect under these circumstances ________．
- A.The ARPA will generate data as if the target was still being tracked by radar
- B.The ARPA will give an audible and/or visual lost target alarm
- C.The ARPA will generate data based on sea return echoes from the vicinity where the target was lost
- D.The ARPA has lost all memory of the target and must recompute the target data
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Which statement about the gyrocompass is FALSE ________．
- A.Its accuracy remains the same at all latitudes
- B.It seeks the true meridian
- C.It can be used near the Earth's magnetic poles
- D.If an error exists，it is the same on all headings
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You have another ship overtaking you close aboard to starboard．You have 3 radar targets bearing 090° relative at ranges of 0.5 mile，1 mile，and 1.5 miles．In this case，the unwanted echoes are called ______．
- A.Multiple echoes
- B.Spoking
- C.Indirect echoes
- D.Side-lobe echoes
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Which statement about the Flinders bar of the magnetic compass is CORRECT ________．
- A.It compensates for the error caused by the vertical component of the Earth's magnetic field
- B.It compensates for error caused by the heeling of a vessel
- C.It compensates for quadrantal deviation
- D.It is only needed in equatorial waters
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What provides little or no indication that a vessel is dragging anchor ________．
- A.Increasing radar range to a fixed object ahead
- B.Drift lead with the line leading perpendicular to the centerline
- C.Vibrations felt by placing a hand on the cable
- D.Changing bearings to distant fixed objects abeam
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When the relative motion display is selected all tracked objects will display ______ vectors．
- A.motion
- B.stationary
- C.dynamical
- D.flashing
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The ______ has a built-in world map; most areas are displayed on a scale of 4000 nm from the top to the bottom of the screen，and can be zoomed in to 150 nm．
- A.chartplotter
- B.C-MAP NT
- C.C-Cards
- D.PPI
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The development of ______ led to the fully automatic ARPA systems installed on commercial ships．
- A.SeaTalk
- B.powerful microprocessors and mega memory capacity
- C.chartplotter
- D.small-scale chart
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The articulated light is superior to other types of buoys because ______．
- A.The radar reflectors reflect better signals
- B.Fog horn signals travel farther to sea
- C.It is equipped with strobe lights
- D.It has a reduced watch circle
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Although manual plotting for CPA works well，the workload can become overwhelming when confronted with ______．
- A.one target
- B.two targets
- C.three targets
- D.a large number of targets
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______ typically extends from close as 0.1 nautical miles out to 32 NM．
- A.EBL
- B.VRM
- C.CRT
- D.target tracking range
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Which magnetic compass corrector（s）CANNOT be set on a heading of magnetic east or magnetic west ________．
- A.Heeling magnet
- B.Flinders bar
- C.Fore-and-aft magnets
- D.All of the above can be set on magnetic east or magnetic west headings
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______ is not used in modern radar．
- A.EBL
- B.VRM
- C.CRT
- D.Grease pencil
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______ is not a job of the radar antenna．
- A.To receive the high-frequency pulses from the transmitter
- B.To focus the pulses into a beam，and send them into space
- C.To pick up reflected pulses coming from objects that have been struck by the beam
- D.To reflect microwaves