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WorksheetsNAV 1 QUIZ 2 2025 MIDTERM
Total questions: 35
Worksheet time: 18mins
Why does deviation happen in a ship’s magnetic compass?
Because of Earth’s magnetic field alone
Because of the ship’s permanent and induced magnetism
Because of chart projection errors
Because of gyro errors
How does a ship’s own magnetism affect the readings of its magnetic compass?
By altering the ship’s speed
By deflecting the compass needle from Magnetic North
By changing the variation angle
By aligning the compass with True North
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.
How does Earth’s magnetic field cause induced magnetism in a ship’s steel hull?
It permanently magnetizes the hull.
It temporarily magnetizes the hull in Earth’s field
It changes the compass graduation.
It eliminates all deviation.
How can ship’s heading, cargo, and magnetic latitude influence compass deviation?
They affect the compass card’s material.
They change magnetic forces on the compass
They reduce variation.
They have no effect on deviation.
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
Why does a ship often experience a change in deviation after being in dry dock for a long time?
Because permanent magnetism in the hull changes.
Because variation decreases.
Because the compass loses sensitivity.
Because cargo weight increases.
How does wrong phase setting affect echo-sounder accuracy?
It disables the stylus motor unit
It causes incorrect timing of pulses
It increases the chart scale error
It removes all shallow water clutter
What is the effect of velocity changes in water on depth readings?
Depth readings become inconsistent
Stylus speed increases automatically
Transducer signal becomes distorted
Display unit resets chart scale
How does the echo-sounder convert sound into visual depth data?
Gain control adjusts signal strength
Stylus burns through chart paper
Echoes are processed and displayed
Transducer emits continuous pulses
Why are multiple echoes more common in deep water?
Sound reflects repeatedly off seabed
Stylus speed increases with depth
Gain control resets automatically
Transducer signal becomes weaker
What should be done when trim and heel affect depth readings?
Adjust draft offset and scale
Disable transducer and restart chart
Increase stylus speed and gain
Level the ship and recalibrate unit
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
Alexander Behm’s invention was applied after 1912. Apply its use to marine navigation today.
Detecting icebergs ahead a
Determining wind strength
Identifying vessel traffic
Measuring depth of sea
A vessel operates echo sounder in shallow water. Apply the setting to avoid overlapping echoes.
Increase chart paper speed
Lower sound velocity input
Use shorter pulse length
Relocate transducer forward
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 believing they create permanent deviation inside the compass
By removing them as they disturb compass card movement
Which statement best defines the Earth's magnetic field and its influence on a magnetic compass?
It's a static force from a solid core.
It's a static force from fixed poles.
It's a dynamic force from a liquid core.
It's a recent, man-made phenomenon.
How is Magnetic Variation best described?
Compass mechanical error.
Angle between needle and keel.
Angle between True and Magnetic North.
Temporary solar storm error.
How is a magnetic compass's alignment with the Earth's poles best described?
North pole aligns with true North Pole.
North pole aligns with magnetic South Pole.
North pole aligns with a fixed magnetic North Pole.
North pole aligns with a shifting magnetic North Pole.
How does a deviation card help mariners navigate accurately using a magnetic compass?
It logs maintenance activities for the compass
It lists compass errors by heading
It serves as an emergency-use document
It shows total magnetic variation for the region
How does Earth’s magnetic field cause induced magnetism in a ship’s steel hull?
It permanently magnetizes the hull.
It temporarily magnetizes the hull in Earth’s field
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 permanent magnetism in the hull changes.
Because variation decreases.
Because the compass loses sensitivity.
Because cargo weight increases.
A vessel in deep water has long pulse intervals. Apply the best operator action.
Reduce chart paper speed
Use deeper range scale
Increase gain sensitivity
Lower transmitted frequency
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 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
A ship displays readings in meters but the navigator needs fathoms. Apply the correct setting.
Change display unit scale
Increase pulse repetition rate
Relocate transducer position
Shorten transmitted pulses
How does a deviation card help mariners navigate accurately using a magnetic compass?
It logs maintenance activities for the compass
It serves as an emergency-use document
It shows total magnetic variation for the region
It lists compass errors by heading
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
What should be done when multiple echoes appear on the depth trace?
Adjust the gain and pulse length
Reduce the stylus speed setting
Reposition the transducer mount
Increase the chart paper feed
How can ship’s heading, cargo, and magnetic latitude influence compass deviation?
They affect the compass card’s material.
They reduce variation.
They change magnetic forces on the compass
They have no effect on deviation.
How does a ship’s own magnetism affect the readings of its magnetic compass?
By altering the ship’s speed
By changing the variation angle
By aligning the compass with True North
By deflecting the compass needle from Magnetic North
If two magnets with opposite poles are placed near each other, what principle explains the force they exert?
Opposite poles attract, so they pull toward each other.
Opposite poles repel, so they push away.
Opposite poles have no effect on each other.
Opposite poles sometimes attract and sometimes repel depending on orientation
How is UKC determined using echo-sounder data?
A. Add draft to measured depth value
B. Subtract draft from measured depth
C Multiply depth by ship’s beam size
D.Divide depth by ship’s length overall
How should a mariner identify the true seabed echo when a vessel encounters false echoes?
A. Increase recording speed
B. Adjust to a deeper scale
C. Select the strongest echo
D. Lower transmitted power
How can a mariner correct for cross noise on the echo-sounder display?
A. Increase the chart scale setting
B. Adjust the swept gain control
C. Disable the stylus motor unit
D. Recalibrate the transducer angle
