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.
What is the primary source of position input for ECDIS?
GNSS
Which input enables the ECDIS to generate a heading marker?
Gyro Compass
Which input creates the small triangle on the ECDIS screen which represents other vessels?
Automated Identification System (AIS)
Which system input is used to display water depth and or UKC on the ECDIS?
Echo sounder
Which input provides the ECDIS with the STW data?
Speed Log
Which system can be overlaid on to ECDIS and used for both position monitoring and assessing risk of collision?
Radar
Which two mandatory alerts relate to the vessels GNSS units?
Change in geodetic datum and positioning system failure.
How many mandatory alerts are there on ECDIS?
Five although three additional ones may be raised either as an alert or an indication.
How many mandatory indications are there for ECDIS?
Twelve although three additional ones may be raised either as an alert or an indication.
What is the difference between an alert and an indication?
An alert is audible (and most likely also visual) whereas an indication is solely visual.
What are the three priorities of an alert on ECDIS?
Alarm, warning and caution
What are the five mandatory alerts on ECDIS?
1.Pass closer than the set distance from safety contour.
2.Deviation from route
3.Positioning system failure
4.Approach to critical point
5.Different geodetic datum
Which electronic chart type enables the interrogation of chart data?
ENC’s
Which electronic chart type is a database of information which is then represented graphically to the user?
ENC’s
Which electronic chart type can make it easier to find information on berth names and numbers?
RNC’s
Which of the ECDIS symbols look more like those found on paper charts?
Traditional
Which UKHO publication provides information about the symbols used on electronic charts?
NP 5012 - Admiralty Guide to ENC Symbols used in ECDIS
What are the four categories of symbols found on ENC’s?
- General
- Navigational aids and services
- Topographical
- Hydrographic
Which category of symbols contains depth sounding?
Hydrographic
Which of the contours take into account a minimum UKC value?
Safety contour
What is the safety depth value normally set to?
The same value as the safety contour
Which contour is intended to indicate to the OOW that the vessel is entering an area where they may start to experience squat?
Safety contour
What does a spot sounding which is deeper than the safety depth look like?
A light grey number
What happens when the look ahead sector touches the safety contour?
An alarm will sound on the ECDIS. This is one of the mandatory alarms.
What’s the difference between the safety depth and safety contour?
Although they use the same value the safety contour acts as the ECDIS no go area, broadly dividing areas of safe and unsafe water in a way thats very obvious and also works with the alarm feature of ECDIS. Safety depth gives further context by highlighting depths shallower than the value set in bold, whereas safe depths are in a less noticeable grey.
In the context of ECDIS, what does interrogating mean?
Click on an ENC object to see more information about it
What is SCAMIN
SCAMIN means scale minimum. It is a filter based on scale, which is used to manage the amount of information displayed on the ECDIS.
Which scale/zoom should we navigate on?
In general we should always navigate on the largest scale cell available for the area in which the vessel is navigating and display that cell at its compilation scale.
How should the position be monitored when using ECDIS?
The GNSS into the ECDIS will provide it with continuous position updates but the OOW must also cross check this position at appropriate intervals using other means, such as visual and radar fixes.
Which ENC standard ensures the consistency of presentation across ECDISS systems?
S-52
Which is the current version of the presentation library?
Version 4 - 2017
What are the four ENC standards?
- S-52
- S-57
- S-63
- S-100
What is the difference between S-57 and S-100?
S-57 is a single standard which defines the procedure to construct an ENC, where is S-100 is a universal hydrographic data model which will enable a variety of S-100 based products.
What are VDR’s used for?
To record data from various systems during a voyage so that this information can be an accessed in the case of an accident, much like the black box on a plan.
Which data remains reliable even with a gyro error or failure?
CPA and TCPA because these are based on relative motion and therefore do not require a speed/heading input.
What is target swap?
Target swap occurs when ARPA-acquired objects pass too close to each other, such as when two vessel’s pass or a vessel passes a fixed object like a buoy. When this happens, the tracking gates end up on top of one another, which can result in the acquisition switching to the other object or, at leas, causing the tracking data to be inaccurate until three minutes have passed.
Why is there a delay between a vessel altering course and this being reflected by the ARPA data?
Because ARPA tracks a vessel’s past motion in order to predict its future motion it is inherently retrospective. If a vessel alters course, the ARPA will provide inaccurate information until the old course is no longer incorporated into its tracking window, which is why we must wait for three minutes.
What will happen to the radar/ARPA if the vessels gyro fails?
The radar is likely to default to another gyro input for its heading, or if none are available, to the TMC (magnetic) heading input. If so, compass error will need to be applied and the magnetic compass may not be steady enough to provide reliable ARPA data, particularly in heavy weather.
What must the OOW do if target swap occurs?
Ensure that both targets are reacquired (if necessary) and ensure that three minutes elapses before the target data is used for collision avoidance again.
What will happen to the radar if all heading inputs fail?
The radar will default to unstabilised head-up orientation.
AIS:
AIS data types:
1. Voyage
2. Static
3 Dynamic
- This info relates to the current voyage of the vessel such as destination, ETA and draft
- Info that is not subject to change such as vessel name, call sign, IMO number, dimensions and type
- Info about the vessel which is consistently changing, including the speed, course, position and heading
AIS:
How often does Class A AIS transmit dynamic info for a vessel alongside?
Every 3 minutes
AIS:
Under the Workboat Code, which vessels are required to carry an AIS unit?
Those operating more than 20nm from land
AIS:
Passenger vessels on international voyages are required to be fitted with which class of AIS?
Class A
AIS:
What is voyage information?
Info relating to the current voyage of the vessel, such as destination, ETA, and draft
AIS:
Over which band do AIS units transmit?
VHF (very high frequency)
AIS:
Which MGN outlines the procedures for the appropriate use of AIS?
MGN 324
AIS:
Why should voyage data not be relied upon?
Because the OOW on the other vessel may not have updated the voyage data before departure, after anchoring, following a change of ETA, etc.
AIS:
Which data should always be given priority on the radar for collision avoidance; AIS or ARPA?
ARPA data must always be given priority for collision avoidance
AIS:
What is an MKD
A Minimum Keyboard Display
AIS:
What are some advantages of AIS data over ARPA?
AIS enables us to see targets which are behind obstructions or in heavy rain and AIS data is current, whereas ARPA data is historical
AIS:
How often does an AIS SART transmit each of its 8 distress messages?
Once a minute
AIS:
Which type of AIS ATON is physical object but has its AIS message transmitted from ashore?
A Synthetic AIS ATON
AIS:
Which type of AIS ATON does not physically exist?
A Virtual AIS ATON
Compass:
Which pole does a magnetic compass point towards?
It points towards the Magnetic North Pole.
Compass:
Which vessels are required to carry a magnetic compass onboard?
All vessels
Compass:
At which pole does the magnetic field exit the earths surface?
At the magnetic South Pole
Compass:
What keeps the compass level in rough seas?
The gimbal
Compass:
Which vessels are required to carry a spare magnetic compass?
Vessels over 150gt, if they aren’t fitted with an approved gyro compass
Compass:
What are the cardinal points?
North, South, East and West
Compass:
Which pole moves slowly over time; magnetic or true?
The magnetic pole moves slowly over time. True north is a fixed geographical point.
Compass:
Calculate the compass error of the variation is 7° west and the deviation is 3° East.
4° West
Compass:
Which type of magnetism changes with the vessels latitude and heading?
Induced magnetism (soft iron)
Compass:
What is metal which acquires permanent magnetism also referred to as?
Hard iron
Compass:
How can the OOW check the deviation that they should expect on a particular heading?
By reference to the vessel’s deviation card
Compass:
Which changes slowly due to the movement of the earths magnetic poles; deviation or variation?
Variation
Compass:
On a paper chart, how is the variation in a location quantified?
The center of the compass rose gives the variation for the year of publication, as well as an annual correction which should be applied in subsequent years.
Compass:
Which type of compass corrector corrects for induced magnetism in the ships funnel?
Flinders bar
Compass:
Who is qualified to swing a magnetic compass?
In the UK, only a compass adjuster holding appropriate compass adjusters CoC May adjust the compass
Compass:
How often must a compass be corrected?
Once every two years, unless a compass record book is being maintained and regular compass checks are being carried out.
Compass:
Which magnets correct for permanent magnetism in a longitudinal direction?
Fore and aft correcting magnets.
Compass:
Which body is typically used to take an amplitude for the purpose of checking the compass error?
The Sun
Compass:
How can the Line of Berth be used to conduct a compass error?
If a large vessel is firmly alongside a straight berth, the vessels heading can be compared to the line of berth from the chart.
Compass:
How often should the compass error be checked?
Once per watch and after each major course alteration.
Compass:
Which method of controlling a gyro changes the gyros path from a circle to an ellipse?
Gravity control.
Compass:
What size vessels should carry a gyro compass?
Vessels over 500gt on international voyages.
Compass:
What is the difference between a gyroscope and a gyrocompass?
A gyroscope is a heavy, free-spinning wheel which points at a fixed location in space, but it can’t be used for navigation (i.e. as a gyrocompass) until it has been controlled through precession and damping to make it point in the same direction.
Compass:
Aside from the bridge, where else must a gyro repeater be fitted?
In the steering gear flat, for use when emergency steering.
Compass:
Calculate the bearing:
Gyro bearing = 095
Gyro Error = 1.5 Low
096.5 True
Compass:
Which factors will increase speed error?
A higher vessel speed, a higher latitude and a more northerly/southerly course.
Compass:
Calculate the gyro bearing:
True bearing = 311 (T)
Gyro error = 0.5 High
Gyro bearing = 311.5
Compass:
What is lubber line error?
The error caused when the gyrocompass isn’t perfectly aligned with the vessels centerline.
Compass:
How are modern gyro errors corrected?
Modern gyrocompasses typically have an input from the GNSS so that the gyrocompass knows the speed, latitude and course and can automatically make corrections. Older models may have manual inputs for key values.
Compass:
How many rings of optical fibre are used to make a fibre optic compass?
Three, one for each axis.
Compass:
What are the carriage requirements for fiber optic compasses?
None. But SOLAS V Reg 19 permits them to be carried in lieu of Gyro compasses.
Compass:
Before using a Pelorus to take a relative bearing, what two things must an OOW align?
The bearing plate with the ships head.
Compass:
What is the azimuth mirror used for?
To take bearings of the sun or other objects that are above the horizon.
Compass:
What must an azimuth ring be fitted to before it can be used?
It just be fitted to the magnetic compass bowl or gyro-repeater.
Speed Logs + Echo Sounders:
Which speed log works by detecting the change in frequency of the returning signal?
A Doppler log.
Speed Logs + Echo Sounders:
Which speed log works by measuring the voltage induced as seawater passes through an electromagnetic field?
An electromagnetic log.
Speed Logs + Echo Sounders:
Which type of speed log is commonly fitted to smaller vessels?
An impeller
Speed Logs + Echo Sounders:
Do echo sounders transmit acoustic or electromagnetic pulses?
Acoustic
Speed Logs + Echo Sounders:
How is the depth calculated by an echo sounder?
The echo sounder transmits a pulse and listens for the echo which returns. The time between transmission and return is divided by 2 and multiplied by the speed of sound in water (1500) to give the distance.
Speed Logs + Echo Sounders:
What is the speed of sound in water?
1500 meters per second (for depth sounding purposes)
Speed Logs + Echo Sounders:
What is a double Janus configuration?
When a speed log transmits fore and aft as well as athwartship.
Speed Logs + Echo Sounders:
When an echo sounder is exhibiting second trace echos, which trace should the OOW rely on?
The OOW should search for the seabed from the top down to make sure that the weaker, true echo is not missed.
Speed Logs + Echo Sounders:
What can affect the accuracy of a Doppler log?
Anything which interferes with the pulse (attenuation by air bubbles or marine growth on the transponder) or which affects its velocity (salinity, particle content and temperature of water). Non-Janice Doppler logs can also be affected by rolling, yawing and pitching errors.
Speed Logs + Echo Sounders:
What is Pythagoras error?
An error caused by the transmitting and receiving components of an echo sounder being in different places on the hull, although this should be corrected for on installation.
Speed Logs + Echo Sounders:
How can trim effect accuracy of an echo sounder?
If a vessel with an echo sounder mounted near the bow is trimmed by the stern, the UKC given by the echo sounder will be more than the actual UKC because the stern is deeper in the water than the bow.
Autopilots and Trackpilots:
Which autopilot mode does not rely on a GNSS?
Heading mode
Autopilots and Trackpilots:
Which vessels should be fitted with an autopilot system?
Vessels over 10,000gt, although autopilots are commonly gotten on vessels of all sizes.
Autopilots and Trackpilots:
What are the risks of operating in course mode?
Although it is a useful tool, the OOW may lose situational awareness and become complacent if they are not monitoring the drift angle, etc.
Autopilots and Trackpilots:
What is the difference between course mode and track mode?
Course mode uses a GNSS input to maintain a given course over the ground.
Track mode takes this one step further and uses an ECDIS input to ensure that the vessel is proceeding along the planned track.
Autopilots and Trackpilots:
What is the drift angle?
The difference between the heading and the course over the ground, expressed in degrees.
Autopilots and Trackpilots:
If the OOW encounters a gyro compass failure whilst using the autopilot, what is their first action?
Engage hand steering.
Autopilots and Trackpilots:
How do weather-related settings affect how an autopilot performs in adverse weather conditions?
They tell the autopilot to accept a certain degree of yawing without reacting, which minimizes steering inputs in bad weather. This can result in better heading-keeping, prevent unnecessary wear and tear, and decrease fuel consumption.
Autopilots and Trackpilots:
How will GNSS failure affect a trackpilot?
Trackpilots use GNSS input to maintain a given course over the ground or to keep to a given track on the ECDIS. Without a GNSS input, it will not be able to perform these functions and is likely to revert to heading control.
Autopilots and Trackpilots:
What should the OOW do if the speed log input fails?
The OOW should switch to hand steering and then ensure that the autopilot has a correct manual speed input before engaging it again.
Autopilots and Trackpilots:
Before engaging hand steering, in which position should the helm be?
Amidships
Autopilots and Trackpilots:
What is yawing?
An oscillation in direction or heading, either side of the desired value.
Autopilots and Trackpilots:
What should happen immediately after hand steering is engaged?
Test. The crew member should apply a couple of degrees of helm each side to ensure that they have control and that the rudder is responding appropriately.
Ancillary Equipment:
For how long prior to an incident is data required to be captured by a VDR?
The ‘fixed’ and ‘float-free’ storage units are required to preserve 48 hours of data from before the incident, whereas the long term storage unit is required to preserve 30 days of data.
Ancillary Equipment:
When must the BNWAS be in operation?
The BNWAS is required to be turned on whenever the vessel is underway at sea, regardless of the time of day.
Ancillary Equipment:
Where is the ‘fixed’ VDR storage unit required to be mounted?
The ‘fixed’ storage unit must be mounted to an external deck of the vessel, so it can be recovered by divers or an ROV. A separate storage unit is required to float free.
Ancillary Equipment:
Which vessels are required to be fitted with a BNWAS?
A Bridge Navigation Watch Alarm System is required to be fitted to cargo vessels over 150gt and all passenger vessels, irrespective of size.
Ancillary Equipment:
How is the ‘float-free’ VDR storage unit meant to be located once it had detached from the vessel?
It must be capable of transmitting a locating signal, similar to that used by an EPIRB.
Ancillary Equipment:
Which vessels are required to be fitted with a VDR?
All cargo vessels over 3000gt and all passenger vessels, irrespective of size.
Ancillary Equipment:
What is a VDR?
A Voyage Data Recorder. It is a recording system installed on vessels to collect and preserve operational and navigational data to aid incident investigation.
Ancillary Equipment:
What happens if the OOW fails to press the BNWAS button at the required interval?
If the OOW fails to respond to the flashing light/buzzer on the bridge, the BNWAS is required to transfer the alarm to the cabin of the master or another officer. If this fails to yield a response, it is required to transfer the alarm to the locations of further crew member, such as an all-Officer call or alarming in the crew mess.
