WorksheetsNAV 1 REVIEW 3
Total questions: 30
Worksheet time: 15mins
What does it indicate if a ship’s compass error changes as the ship’s heading changes?
The compass is affected by variation.
The error is caused by deviation.
The ship is at the magnetic equator.
The compass card is misaligned.
Why are compass correctors like soft iron spheres and a Flinders bar used on ships?
To align the compass with True North.
To minimize deviation by balancing magnetic forces
To measure magnetic dip.
To calculate variation more accurately.
How does a seafarer confirm that the magnetic compass card moves freely?
By heating the compass bowl to reduce friction.
By checking that it oscillates slightly then settles quickly.
By tilting the ship deliberately to test movement.
By removing magnets near the helm before observation.
How should a mariner identify the true seabed echo when a vessel encounters false echoes?
Select the strongest echo
Increase recording speed
Adjust to a deeper scale
Lower transmitted power
A survey requires depth in fathoms. The sounder shows 36 meters. Apply the conversion to fathoms.
18 fathoms
20 fathoms
24 fathoms
12 fathoms
A ship displays readings in meters but the navigator needs fathoms. Apply the correct setting.
Increase pulse repetition rate
Change display unit scale
Relocate transducer position
Shorten transmitted pulses
A chart indicates 50 meters but the sounder reads 47 meters. Apply the best adjustment for accuracy.
Check sound velocity input
Change paper recording speed
Shift transducer forward
Increase pulse repetition rate
A vessel in deep water has long pulse intervals. Apply the best operator action.
Use deeper range scale
Reduce chart paper speed
Increase gain sensitivity
Lower transmitted frequency
What step helps correct stylus speed error during operation?
Stabilize voltage to stylus motor
Increase gain to reduce clutter
Adjust zero line to match depth
Reposition transducer near keel
What should be done when multiple echoes appear on the depth trace?
Reduce the stylus speed setting
Adjust the gain and pulse length
Reposition the transducer mount
Increase the chart paper feed
How should a mariner adjust the echo-sounder to avoid shallow water clutter?
Increase the stylus speed setting
Adjust the gain and pulse length
Change the transducer location
Disable the depth recorder unit
How should a mariner respond to false echoes from thermal layers?
Increase stylus speed for clarity
Adjust gain and verify seabed trace
Disable transducer and restart unit
Recalibrate the depth scale setting
How can aeration be identified on the echo-sounder display?
Dots and irregular marks appear
Depth trace becomes a straight line
Stylus burns through chart paper
Gain control resets automatically
A ship uses bathymetric navigation. Apply knowledge to identify which feature must be compared with charts.
Magnetic compass bearings
Atmospheric pressure values
Ocean surface wave heights
Geological seabed profile
How should a mariner apply knowledge of Earth’s magnetic field to determine the initial direction shown by a ship’s magnetic compass?
By recognizing it attracts the compass toward the true geographic north pole
By understanding it aligns the compass with Earth’s magnetic North
By assuming it forces the compass to point eastward regardless of location
By knowing it stabilizes the compass card against the ship’s motion
How should a mariner apply knowledge of the liquid inside a magnetic compass to ensure proper operation?
By believing it eliminates variation and deviation
By knowing it reduces friction and steadies the compass card
By using it to align the compass needle with true north
By relying on it to detect annual variation
How can a navigator ensure proper maintenance of the magnetic compass?
Ignore deviations during short trips since they are minor.
Replace the compass card after every voyage.
Check for leaks, bubbles, and free movement
Adjust annual change directly on the compass face.
How can deviation from permanent magnetism be reduced?
Recalculate annual change of variation each year.
Place and adjust corrector magnets near the compass.
Record deviation without using compensation devices.
Use only a liquid-filled compass instead of a dry one.
A magnetic compass is primarily designed to align with which of the following?
The Earth’s lines of longitude.
The celestial North Star.
The Earth’s geomagnetic field lines.
The local gravitational field.
How does the concept of 'annual change' affect magnetic navigation over time?
It results from poor compass maintenance
It causes yearly changes in deviation values
It alters compass accuracy every voyage
It reflects the gradual shift of Earth’s magnetic poles
Why are multiple echoes more common in deep water?
Stylus speed increases with depth
Gain control resets automatically
Sound reflects repeatedly off seabed
Transducer signal becomes weaker
How should a mariner respond when the echo sounder shows multiple echoes stacked below the seabed line?
Calibration adjustment line
Double reflection error
Actual seabed position
Incorrect frequency setting
What should a mariner do to apply knowledge of variation and deviation when determining the ship’s true heading?
Align the compass with GPS data
Prevent the ship from rolling and pitching
Adjust the compass course to find the true heading
Eliminate all compass errors permanently
Why do opposite magnetic poles attract each other according to the principles of magnetism?
Because their magnetic fields complement and pull together
Because they have no measurable interaction
Because they sometimes attract and sometimes repel randomly
Because they repel each other due to field resistance
How can a mariner correct for cross noise on the echo-sounder display?
Increase the chart scale setting
Disable the stylus motor unit
Recalibrate the transducer angle
Adjust the swept gain control
A return echo is too weak over soft mud seabeds. Apply the adjustment needed on the equipment.
Increase gain sensitivity
Lower transmitted frequency
Shorten transmitted pulses
Decrease chart paper speed
How should a mariner apply knowledge of magnetic compass maintenance when bubbles are present?
By assuming they cause the compass to shift eastward on all headings
By thinking they alter Earth’s magnetic field around the vessel
By removing them as they disturb compass card movement
By believing they create permanent deviation inside the compass
How is a magnetic compass's alignment with the Earth's poles best described?
North pole aligns with magnetic South Pole.
North pole aligns with true North Pole.
North pole aligns with a fixed magnetic North Pole.
North pole aligns with a shifting magnetic North Pole.
How does Earth’s magnetic field cause induced magnetism in a ship’s steel hull?
It temporarily magnetizes the hull in Earth’s field
It permanently magnetizes the hull.
It changes the compass graduation.
It eliminates all deviation.
Why does a ship often experience a change in deviation after being in dry dock for a long time?
Because variation decreases.
Because the compass loses sensitivity.
Because cargo weight increases.
Because permanent magnetism in the hull changes.
