Bridge Equipment Flashcards
How many satellites must be in sight of the receiver unit in order to provide a 3D position?
4
Under SOLAS, which vessels are required to carry a GNSS unit?
All vessels involved in international voyage no mater what size
Which was the original GNSS system
The American NAVSTAR
Global Position System (GPS)
What is an advantage of GLOBAS over GPS
GLOBAS constellation provides better accuracy at high latitudes
What type of course data will be provided by a GNSS
Course over ground (COG)
How does a GNSS present position data
Latitude & Longitude
What does a GNSS give speed in reference to?
Always Speed over ground
Is a more accurate position fix indicated by a smaller or larger DOP value?
Smaller
How does RAIM work?
(Receiver Autonomous Integrity Monitoring)
For receivers using the NAVSTAR GPS constellation, it uses additional satellite that are within range to cross check the integrity of the position data.
What is SBAS?
Space Based Augmentation Systems
Augmentation methods improve the accuracy,reliability and availability of GNSS devices using external information to help with the calculation of position
What is the current status of DGPS in the UK?
DGPS was the primary for ground based augmentation systems in the UK but the service was terminated in 2022
According to MGN 379, what is the approximate accuracy of GNSS derived positions?
5-25m, 95% of the time
However high quality receivers may achieve better results and augmentation systems may increase accuracy to 1m or less.
Which interference is the deliberate substitution of a genuine position with a fake one?
Spoofing
Which error can occur when the GNSS signal bounces off a vessels funnels before being received by the antennas?
Multi Path Error
How does the radar understand the bearing of detected objects?
By reference the the vessels heading
What vessels are required to carry an X-Band radar?
Vessels over 300gt
Why must the first radar carried by a vessel be an X-Band?
Because only X-Band radar are able to detect SART’s
What vessels are required to carry an additional X-Band or an S-Band radar?
Vessels over 3000gt are required to carry either two X-Band radars or one of each
Why do most large vessels carry an X-Band and an S-Band radar?
Because each has its advantages and it’s best to carry on of each.
A radar must ensure that targets can be detected while the vessel encounters a roll of up to how many degrees?
+| - 10 degrees
What is the required bearing accuracy for detected objects?
Within 1 degree
What are the requirements for range discrimination of a radar?
In calm conditions on a range scale of 1.5nm or less, the radar must be capable of displaying two point targets on the same bearing, separated by 40m in range as two distinct objects
What are the requirements for bearing discrimination of a radar?
In calm conditions, on a range scale of 1.5nm or less, the radar must be capable of displaying two point targets at the same range, separated by 2.5 degrees in bearing as two distinct objects
When should you conduct a performance monitor on your radar?
On start up and once per watch
Which type of clutter control reduces the amplification of the returning pulse in the vicinity of the vessel?
Sea clutter
What is the correct order in which to set up a radar
Brilliance - Gain - tune
Rain before sea
RADAR
How should the gain on your radar be set for optimal performance?
It should be increased until a lightly speckling appears across the screen and then decrease ever so slightly until the speckling disappears
What should the performance monitor results be checked against?
(Radar)
The image in the manufacturers instructions
RADAR
Which speed input is used with a sea stabilized radar
Speed Log giving the vessels speed through the water (STW)
In open sea, why is sea stabilization of the radar preferred for collision avoidance?
Because the true vector of the other vessel will give a more accurate representation of the other vessels aspect
In coastal or pilotage waters, why may ground stabilization of the radar be preferred?
Because ground stabilization may improve situational awareness because land and other fixed objects won’t display trails in true motion (which reduces clutter) and the radar will provide the OOW with a clear indication of our true vector on the screen
Which radar setting fixes the vessel at one point of the screen and causes objects on the screen to move around the vessel as if it was not moving ?
Relative motion
Which radar orientation is not stabilized?
Head up
Which error causes multiple targets at the same bearing but different ranges?
Multi path error
How much sea and rain clutter should be used on our radar
The minimum necessary to achieve a usable image. We should not attempt to have a clear radar screen?
Which error results from additional weaker radiation emitting from the radar scanner?
Side lobe error
What causes indirect echo error?
When the radar pulse returns to the scanner having bounced off of part of the ship’s structure such as the funnel.
What is likely to occur in a vessels blind sector?
Targets will not be detected or acquired, targets are likely to be lost.
Which may be more accurate, especially on smaller vessels; radar ranges or bearings?
Ranges due to the beam width causing poor bearing discrimination
How many lines must be used for all position fixes?
A minimum of three
How should charted objects/features be selected for use in position fixing using radar?
objects/features must be radar conspicuous and easily identifiable so that there isn’t any inaccuracy or confusion when applying the range/bearing to the chart/bearing.
Which MGN gives guidance on the use of electronic navigation aids?
MGN 379
Why is parallel indexing referred to as a real time method?
Because it enables continuous monitoring of the vessels position, as opposed to fixes which are always historic.
Which technique is used to help the OOW monitor the cross track distance?
(Radar)
Clearing ranges
Which technique is used to help ensure that the vessel stops at the required point?
Dead range
When should PI’s be identified and marked on the chart?
During the passage planning process
How does a SART indicate its position on an X Band radar at a range of approximately 6nm?
Arcs
What is the battery life of a SART in passive mode
96 hours
Where is the SART located in relation to the twelve dots.
At the first dot
Which type of radar can detect SART’s?
X-Band
What pattern does a RACON form on the radar screen?
A series of dots and dashes to create a Morse code letter.
How long does the OOW have to wait before taking decisions based onARPA data?
3 minutes
What size vessels are required to carry ARPA
Vessels over 10,000 GT
What does ARPA stand for?
Automatic Radar Plotting Aid
ARPA:
Which mode gives us a prediction of the future movement of another vessel in relation to our vessel?
Relative vectors
ARPA:
Which mode gives us a historic representation of a vessels actual motion?
True trails
ARPA:
What information can relative vectors provide at a glance?
An indication of whether a target could have risk of collision (when the vector is pointing towards our vessel)
ARPA:
How many targets should an ARPA be capable of tracking simultaneously?
40 targets
Which system is used to assist the OOW with manual plotting targets?
Electronic Plotting Aid (EPA)
Which system enables automatic tracking of targets but isn’t required to acquire them automatically?
Automatic Tracking Aid (ATA)
Which system must be capable of carrying out a trial maneuver?
Automatic radar plotting aid (ARPA)
How quickly is ARPA required to provide primary CPA and TCPA data?
One minute
How quickly must the ARPA provide accurate CPA/TCPA data on which collision avoidance can be made?
3 minutes
Which vessels are required to carry full ECDIS?
All new built passenger ships of 500 GT or newly-built cargo ships (including tankers) of 3000 GT or more on international voyages.
Must a vessel carry two independent ECDIS’s to meet the carriage requirements of SOLAS V R 19?
No it is also a acceptable to carry an appropriate folio of paper charts
If a vessel does carry an additional ECDIS unit as a backup, what are the additional requirements?
It must be an independent type approved ECDIS unit with a separate (normal and emergency) power supply and GNSS input.
If an additional folio of paper charts is carried as a backup what are the additional requirements?
The paper charts must be
1. corrected and
2. kept up to date at all times
3. be readily available
4. the passage plan must be indicated on the chart
Which part of SOLAS states the carriage requirements for ECDIS?
SOLAS V (Safety of Navigation) Regulation 19 (Carriage requirements for ship-born navigation system and equipment.
What dose ECDIS stand for?
Electronic Chart Display and Information System
What is the primary purpose of ECDIS?
To enhance the safety of navigation
How can OOW’s avoid becoming over reliant on ECDIS?
By regularly cross checking the position given by the ECDIS and by thoroughly understanding the limitations of the system.
What is datum shift?
Datum shift is when the datum used to derive the position doesn’t match the datum on the chart on which that position is plotted.
What is alarm fatigue?
Alarm fatigue is when users who are exposed to high levels of spurious/false alarms begin to be desensitized and fail to respond to alarms appropriately.
What is an ECS?
An Electronic Chart System which does not meet the performance standards laid down by the IMO for it to be classed as an ECDIS.
What are the training requirements for the use of ECDIS?
All officers using ECDIS must have attended generic ECDIS course and have received type specific ECDIS training
Are officers required to complete type specific ECDIS training?
No but the company must ensure that their officers are appropriately trained and familiarized with the equipment. This maybe through a course or a program of onboard training.
Where is the vessels approval to use ECDIS as the primary means of navigation recorded?
On the vessels record of equipment, which is part of the Cargo Ship Safety Equipment Certificate ( Also known as form E) or the passenger ship safety certificate ( Also known as form P)
What must the SMS contain regarding ECDIS?
It must include procedures for carriage and safe operation with ECDIS.