This page contains answers to Seagull CES test about Radar Plotting and Observation, and serve as a database of questions and answers, using which seafarer can prepare to exams for getting certificate of competence, or just to challenge yourself with knowledge in this theme.
Test about Radar Plotting and Observation
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Amount of questions: 53.
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Can the frequency of radar pulses transmitted per second affect the radar’s maximum range?
No.
Yes.
Only at short range.
Only during rain, snow etc.
Does the Collision Regulations give any preference to ships equipped with radar?
No.
Yes.
Only in good visibility.
Only during reduced visibility.
Does the ships trim affect radar minimum range?
No.
Yes, it may introduce obstructions and blind sectors.
Only at long distance.
Only at short distance.
How can the Beam Width Distortion be minimized?
Adjust centre position.
Adjust the setting of the Brilliance control.
Adjust Heading Marker.
Reduce the setting of the Gain control.
How can the horizontal extent of a “Blind Sector” be accurately determined?
By visually looking for on-board obstructions.
By turning the ship through 360° and determining when a strong echo disappears and reappears on the radar screen.
By determining the direction of indirect echoes.
By looking at the sectors on the radar display with no sea clutter.
How does radar antenna height influence on sea clutter?
High antenna height results in less sea clutter being displayed.
High antenna height results in more sea clutter displayed on the screen.
Antenna height has no effect on the amount of sea clutter displayed.
Low antenna height results in more sea clutter being displayed.
How is the amplifier protected from the transmitted pulse?
By the Transmitter/Receiver switch.
By timing the pulse transmissions to precise times.
By having separate transmission and receiver scanners.
Not necessary.
IMO resolution 477 applies to all ships built after:
1972.
1982.
1984.
1992.
Is it a requirement to have the HM-suppress button spring loaded?
No requirement.
Yes, it is a IMO requirement.
HM-switch may be spring loaded.
HM-switch must not be spring loaded.
Marine radar bearing accuracy is generally:
Not very good.
Good, but not as good as the range rings.
Excellent.
Bad.
Marine radar range accuracy is generally:
Excellent, but better with the VRM than the fixed rings.
Good, but the range rings are better than the VRM.
Poor.
Variable.
The action taken to avoid collision in reduced visibility should be:
Always by a large alteration of course to starboard.
Always by a reduction of speed.
Sometimes by no alterations as own ship may be the “Stand-on” vessel.
Positive, in ample time and avoiding a series of small alterations.
The actions required by the Collision Regulations can be ignored when:
In a traffic separation Line.
In clear visibility.
When at anchor.
Never.
The radar must be able to operate in relative wind speeds up to:
50 knots.
75 knots.
100 knots.
No requirement.
The reflection of radar pulses is similar to that of?
Sound waves.
Ice.
Snow.
Light waves.
We have normal transmission of radar waves when the radar horizon is:
The same as the visible horizon when at the same vertical height.
10 % longer than the visible horizon.
25 % longer than the visible horizon.
50 % longer than the visible horizon.
What is known as “Side Lobes” with reference to marine radar?
The unwanted affects on magnetic compass, when being close to radar equipment.
Unwanted lobes of energy transmitted outside the main radar transmission beam.
The separate transmissions eventually being returned to the scanner after bouncing back and forth between the sides of own ship and another vessel.
The horizontal extensions of the radar scanner.
What is sometimes known as a Coded Racon?
A racon, which automatically activate itself.
A racon only working at night.
A racon, which displays a Morse code on the radar screen.
A racon, which has the transmitter sending a signal continuously.
What is the correct setting for the “Gain” control?
No noise (speckled effect) visible on the screen.
A noise (speckled effect) visible across the whole screen.
No sea clutter remains visible on the screen.
A little noise (speckled effect) remains visible on the screen.
What is the correct type of radar display to be selected when at sea?
Always use a compass stabilized display either True Motion or Relative Motion to suit experience and environment.
Always use ships Head-up unstabilised display.
Always a North-up Stabilized Relative Motion display.
Always a North-up Stabilized True Motion display.
What is the effect of Sub-refraction?
Distance to the radar horizon is reduced.
Distance to the radar horizon is increased.
Distance to the radar horizon not effected.
Possible radar black-out.
What is the effect of error in own ships speed, when completing a plot?
Error in calculated CPA and TCPA.
Error in the targets course and speed.
Error in calculated target aspect and CPA.
Error in CPA, TCPA and target course.
What is the effect of gyro error?
All bearings will be ignored.
All ranges will be wrong.
Bearings and ranges will be wrong.
None of the three alternatives.
What is the fundamental principle of a marine radar?
Detection of other objects outside own ship.
Provide early warning of ships.
Determine the course of other ships.
Provide an early warning of ships on collision course.
What is the main content of Rule 19 in the Collision Regulations?
The conduct of vessels in sight of one another.
The necessity of keeping a proper lookout.
The conduct of vessels in restricted visibility.
The conduct of vessels in any visibility.
What is the main disadvantage of true plotting?
It provides immediate collision risk information.
Collision risk (CPA) can only be found by completing the plot.
The chart scale is not always suitable to be used for true plotting.
Can be done on ordinary piece of paper.
What is the main function of the antenna?
To transmit radar signals.
To receive radar signals from objects outside own vessel.
To transmit the radar signals and receive echoes from objects.
To provide information about echo range bearing.
What is the main function of the receiver?
Amplify the incoming signals.
Amplify the outgoing signals.
Display signals of interest.
Reduce receiver noise.
What is the main purpose of plotting?
Obtain CPA and TCPA only.
Obtain target course and speed only.
Obtain information about whether danger of collision exists, CPA, TCPA, target course and speed.
Obtain target-calculated aspect only.
What is the main purpose of the parallel index lines?
To assist the navigator in maintaining the ships heading.
To assist the navigator in maintaining the ships steered course.
To assist the navigator in maintaining the desired course over the ground.
To assist the navigator in finding the ships set and drift.
What is the maximum radar “warm-up” time?
1 min.
2 min.
3 min.
4 min.
What is the meaning of “Radar Bearing Discrimination”?
The radar ability to display as separate spots on the screen, close targets on the same range.
The radar ability to display as separate spots on the screen, close targets on the same bearing.
The radar ability to pick up large targets.
The radar ability to pick up small targets.
What is the meaning of “Radar’s Range Discrimination”?
The radar ability to display as separate spots on the screen, close targets on the same range.
The radar ability to display as separate spots on the screen, close targets on the same bearing.
The radar ability to provide accurate bearings of small echoes.
The radar ability to provide accurate ranges of small echoes.
What is the minimum display diameter required on ships bigger than 1 600 tons but less than 10 000 tons?
250 mm.
340 mm.
360 mm.
380 mm.
What is the minimum number of range scales required?
2.
3.
5.
6.
What is the minimum radar display diameter for ships of 10 000 tons and upwards?
9 inch.
12 inch.
16 inch.
20 inch.
What is the purpose of a radar reflector?
Making objects less radar visible.
Making small targets more visible to the eye.
Making large echoes smaller.
Making small objects more radar visible.
What is the purpose of determining the Aspect of a target vessel?
Provide the relative bearing of the target.
Provide the same information as could be seen visually out of the wheelhouse.
Determine the probable reflective properties of the target.
Avoid a collision risk developing.
What is the purpose of the Anti-Sea Clutter controls?
Reduces the amount of echoes from the sea waves.
Reduces the strength of the transmitted signal.
Reduces the height of the sea waves.
Reduces the affects of the echo returns from the sea waves.
What is the purpose of the Gain control?
To adjust the amount of amplification of the echoes.
Adjust antenna sensitivity.
Adjust the strength of the transmitted signal.
Adjust the brightness of the screen.
What is the purpose of the Heading Line (HL) suppression control?
To switch off the HL permanently in order to see under the line on the screen.
To switch off the HL temporarily in order to see under the line on the screen.
To switch on the HL.
To adjust the position of the HL in azimuth.
What us the purpose of the VRM control?
To measure distance of a target on the screen accurately from own ship.
To measure bearing of a target on the screen accurately.
To measure range and bearing of a target on the screen accurately.
To measure the length of all the target trails on the screen.
What is the quickest method of deciding whether collision danger exists or not?
By taking several bearings of the target.
By taking several range measurements to the target.
By true plotting.
By relative plotting.
What is the relation between the scanner’s horizontal width (size) and horizontal beam width?
No relation.
Small scanner horizontal width, narrow horizontal beam width.
Large scanner horizontal width, narrow horizontal beam width.
Large scanner horizontal width, wide horizontal beam width.
What is the required accuracy of the heading marker?
+/- 0,5°.
+/- 1,0°.
+/- 1,5°.
No requirement.
What radar range should be selected to suit all conditions?
The 12 miles range.
The 12 miles range with frequent changes to higher ranges to determine distant targets.
The range most suitable to the proximity of targets and land, but with frequent checks of higher and lower ranges.
The 6 mile range with frequent observations of the 12 mile range.
When completing a full Relative plot (North up), what input information is required?
A series of target ranges and bearings and own ships course and speed over the ground.
A series of target ranges and bearings and own ships course and speed through the water.
A series Ranges and bearings only.
The CPA and TCPA.
When does a radar display the identity signal of a racon?
When the wavelength of the racon is similar to the radar in use.
Always when using all marine radars.
Always when using a S-band radar.
No radar can activate a racon.
Which course should be fed in to the radar with a stabilised radar picture?
Magnetic Compass course steered.
Master Gyro course steered.
True course steered by own ship.
True course made good over the ground.
Which of the following provides the complete answer, when related to the effect of using incorrect bearings in plotting?
Calculation of CPA is effected.
Calculation of TCPA is effected.
Calculation of target course and speed are effected.
CPA, TCPA, Course and Speed of the target are effected.
Which of the radar controls can be left at the setting determined when the set was first switched on?
Tuning control.
None.
Sea Clutter.
Pulse length.
Which radar condition can be associated with a temperature inversion?
Ducting.
Sub-refraction.
Super refraction.
Radar black-out.
Why should radar still be used during the day in clear visibility?
To avoid looking out the wheelhouse windows.
To improve confidence and competence in the use of that specific radar.
To remove the necessity of keeping a good lookout.
Because radar is the only method to determine any risk of collision from other ships.
Test about Radar Plotting and Observation
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