Worksheetsmidterm quiz 1 nav 1
Total questions: 30
Worksheet time: 15mins
What is the main function of an echo-sounder?
To accurately determine the ship's position
To measure the depth of the water below the ship
To locate and identify objects on the seabed
To communicate with underwater vehicles
What does the acronym SONAR stand for?
Sound Observation and Ranging
Sound Navigation and Ranging
Sonar Operations and Reporting
Sounding Navigation and Recording
Which physicist is credited with inventing echo-sounding?
Alexander Graham Bell
Alexander Behm
Thomas Edison
Robert Fulton
What is the purpose of the transducer in the echo-sounder?
It records the depth on a paper chart
It converts sound waves to electrical signals
It generates the electrical pulses for transmission
It amplifies the returning echo signal
What is the approximate speed of sound in water?
1500 meters per second
1000 meters per second
500 meters per second
2000 meters per second
How is the depth calculated by an echo-sounder?
Using time and the ship’s speed over ground
Using the time interval and sound speed in water
Using the frequency of the returning sound signal
Using the amplitude of the initial sound pulse
What is a common cause of 'cross noise' in an echo-sounder?
A very low gain setting on the receiver
A malfunctioning transducer element
Air bubbles passing over the transducer
The ship being in a state of trim or heel
What is the function of the receiver component?
It converts electrical pulses into sound waves
It generates the high-voltage electrical pulses
It processes and amplifies the returned signal
It displays the depth reading visually on a screen
What is a common cause of 'false echoes'?
An incorrect zero line adjustment
Multiple reflections from the seabed
The stylus speed being set incorrectly
The presence of a 'Pythagoras error'
What is UKC short for in marine navigation?
Underwater Keel Clearance
Under-Keel Compensation
Ultimate Keel Coefficient
Under-Keel Clearance
Why is the time for the echo to return halved in the depth formula?
To account for the density layers in the water
Because the signal travels to the bottom and back
To correct for the ship's speed through the water
Because the sound pulse weakens on its journey
How can a ship’s trim or heel cause an inaccuracy in depth?
It increases the speed of sound in the water column
It causes the transducer to not point directly downward
It changes the frequency of the sound waves being sent
It creates multiple echo reflections from the seabed
Why do salinity, temperature, and pressure affect an echo-sounder?
They directly alter the speed of the stylus motor
They cause the transducer to overheat and fail
They change the speed of sound in the water
They can cause a severe 'Pythagoras error'
How does an incorrect zero line adjustment affect readings?
It causes the stylus to move at an irregular speed
It produces a consistent error in all depth readings
It can lead to the transducer overheating and failing
It results in a complete loss of the depth display
What is the main reason for a 'Pythagoras error' in a two-transducer system?
The distance between the transmitter and the receiver
The difference in the time it takes for a pulse to return
The incorrect amplifier gain setting on the receiver
The wrong phase setting is being used by the system
A ship's echo-sounder measures a return time of 0.1 seconds. What is the approximate depth?
75 meters
150 meters
100 meters
1500 meters
A ship has a draft of 6 meters and the echo-sounder reads 25 meters. What is the UKC?
19 meters
21 meters
25 meters
31 meters
A navigator adjusts the echo-sounder to a different unit setting. What kind of error is being avoided?
False echo
Scale error
Stylus speed error
Pythagoras error
A mariner adjusts the gain control to reduce the irregular dots near the zero line. What issue are they correcting?
Multiple echoes
Stylus speed error
Cross noise
Pythagoras error
If a ship’s echo-sounder consistently shows a depth of 10 meters deeper than charts, what is a likely cause?
The amplifier gain is set too low
The stylus speed is too slow
The zero line is adjusted incorrectly
The transmitter is failing
Why is a high-sensitivity amplifier a potential source of error?
It can increase the ship's trim and heel
It may pick up and amplify irrelevant signals
It reduces the overall power output of the transducer
It can cause the zero line to become unstable
How does a transducer covered in marine growth affect the reading?
It can introduce a significant Pythagoras error
It will increase the speed of sound in the water
It can scatter the sound pulses, weakening the echo
It changes the ship’s draft, affecting the UKC
Why would a navigator use event markers on an echo-sounder?
To manually correct for the speed of sound error
To log a specific point in time or location
To manually adjust the stylus speed
To compensate for the ship's trim and heel
If the echo-sounder shows multiple lines of varying depths, what is the most likely cause?
A stylus speed error
A scale error on the display
Multiple echoes from the seabed
The zero line is incorrectly adjusted
What is the primary factor that makes a 'Pythagoras error' more prominent?
The number of transducers used
The physical separation between transducers
The velocity of sound in the water
The sensitivity of the receiver amplifier
Why is cross-checking the echo-sounder reading with charts considered a crucial safety practice?
To ensure the charts are always accurate and up-to-date
To verify the echo-sounder reading and prevent groundings
To make sure the zero line is always properly adjusted
To determine the exact speed of sound in the water
In what scenario is the UKC reading of highest navigational importance?
When a ship is in open sea with unlimited depth
When a ship is navigating in a deep, narrow channel
When a ship is transiting a shallow, confined channel
When a ship is moored at a protected port facility
How would you best correct for a stylus speed error on an old paper-based echo-sounder?
By increasing the frequency of the electrical pulses
By recalibrating the stylus motor's power supply
By adjusting the transducer’s angle on the hull
By manually adjusting the gain on the receiver
Why is the proper setting of the ship's draft offset critical for accurate UKC calculation?
It ensures the depth is measured from the keel of the ship
It calibrates the stylus speed for the entire voyage
It removes all false echoes from the display screen
It accounts for the changing velocity of sound in water
When is it most important to consider the potential for multiple echoes?
When operating the echo-sounder in extremely deep water
When the ship is in a state of trim or heel
When navigating in very shallow water over a hard bottom
When the amplifier gain is set too low
