Radar (Seagull Training) Flashcards
Does the Collision Regulations give any preference to ships equipped with radar?
No.
Does the ships trim affect radar minimum range?
Yes, it may introduce obstructions and blind sectors. Only at short distance.
How can the Beam Width Distortion be minimized?
Reduce the setting of the Gain control.
How can the horizontal extent of a “Blind Sector” be accurately determined?
By turning the ship through 360 degrees and determining when a strong echo disappears and reappears on the radar screen..
How does radar antenna height influence on sea clutter?
High antenna height results in more sea clutter displayed on the screen.
How is the amplifier protected from the transmitted pulse?
By the Transmitter/Receiver switch.
IMO resolution 477 applies to all ships built after?
1984
Is it a requirement to have the HM-suppress button spring loaded?
Yes, it is a IMO requirement.
Marine radar bearing accuracy is generally?
Good, but not as good as the range rings.
Marine radar range accuracy is generally?
Good, but the range rings are better than the VRM.
The action taken to avoid collision in reduced visibility should be:
Positive, in ample time and avoiding a series of small alterations.
The actions required by the Collision Regulations can be ignored when:
Never.
The radar must be able to operate in relative wind speeds up to?
100 knots
The reflection of radar pulses is similar to that of?
Light waves.
We have normal transmission of radar waves when the radar horizon is?
10% longer than the visible horizon.
What is known as “Side Lobes” with reference to marine radar?
Unwanted lobes of energy transmitted outside the main radar transmission beam.
What is sometimes known as a Coded Racon?
A racon which displays a Morse code on the radar screen..
What is the correct setting for the “Gain” control?
A little noise (speckled effect) remaining 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.
What is the effect of error in own ships speed, when completing a plot?
Error in the targets course and speed.
What is the effect of gyro error?
All bearings will be wrong.
What is the effect of Sub-refraction?
Distance to the radar horizon is reduced.
What is the fundamental principle of a marine radar?
Detection of other objects outside own ship.
What is the main content of Rule 19 in the Collision Regulations?
The conduct of vessels in restricted visibility.
What is the main disadvantage of true plotting?
Collision risk (CPA) can only be found by completing the plot.
What is the main function of the antenna?
To transmit the radar signals and receive echoes from objects.
What is the main function of the receiver?
Amplify the incoming signals.
What is the main purpose of plotting?
Obtain information about whether danger of collision exists, CPA, TCPA, target course and speed.
What is the main purpose of the parallel index lines?
To assist the navigator in maintaining the desired course over the ground..
What is the maximum radar “warm-up” time?
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.
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 bearing.
What is the minimum display diameter required on ships bigger than 1600 tons but less than 10 000 tons?
250 mm
What is the minimum number of range scales required?
5
What is the minimum radar display diameter for ships of 10 000 tons and upwards?
16 inch
What is the purpose of a radar reflector?
Making small objects more radar visible.
What is the purpose of determining the Aspect of a target vessel ?
Provide the same information as could be seen visually out of the wheelhouse window.
What is the purpose of the Anti Sea Clutter controls?
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.
What is the purpose of the Heading Line (HL) -suppression control
To switch off the HL temporarily in order to see under the line on the screen.
What is the purpose of the VRM control?
To measure distance of a target on the screen accurately from own ship..
What is the quickest method of deciding whether collision danger exists or not?
By taking several bearings of the target..
What is the relation between the scanner’s horizontal width (size) and horizontal beam width?
Large scanner horizontal width, narrow horizontal beam width.
What is the required accuracy of the heading marker?
+/- 1.0°
What radar range should be selected to suit all conditions?
The range most suitable to the proximity of targets and land, but with frequent checks of higher and lower ranges.
When completing a full Relative plot (North up), what input information is required?
A series of target ranges and bearings and own ship’s course and speed through the water.
When does a radar display the identity signal of a racon?
When the wavelength of the racon is similar to the radar in use.
Which course should be fed in to the radar with a stabilised radar picture?
True course steered by own ship.
Which of the following provides the complete answer, when related to the effect of using incorrect bearings in plotting?
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?
None.
Which radar condition can be associated with a temperature inversion?
Ducting.
Why should radar still be used during the day in clear visibility?
To improve confidence and competence in the use of that specific radar.
Can the frequency of radar pulses transmitted per second affect the radar’s maximum range?
Yes.
