Bridge Equipment Flashcards
What does ECDIS stand for?
Electronic Chart Display and
Information System
What is the primary purpose of ECDIS?
To enhance the safety of navigation.
How can OOWs 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 of 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 desensitised and fail to respond to alarms appropriately.
What is an ECS?
An Electronic Charting System which does not meet the performance standards laid down by the IMO for it to be classed as an ECDIS.
Which vessels are required to be fitted with ECDIS?
All newly-built passenger ships of 500gt or more and all newly-built cargo ships (including tankers) of 3,000gt or more, on international a voyages.
Must a vessel carry two, independent ECDIS systems to meet the carriage requirements of SOLAS V R19?
No, it is also acceptable to carry an ‘appropriate folio’ of paper charts.
If a vessel does carry an additional ECDIS unit as a back-up, 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 ‘appropriate folio’ of paper charts is carried as a back-up, what are the additional requirements?
The paper charts must be corrected and kept up-to-date at all times, be readily available and the passage plan must be indicated on the charts.
Which part of SOLAS states the carriage requirements for
ECDIS?
SOLAS Chapter V (Safety of Navigation), Regulation 19 (Carriage requirements for shipborne navigational systems and equipment).
What are the training requirements for the use of
ECDIS?
All Officers using ECDIS must have attended a Generic
ECDIS Course and have received type-specific ECDIS
Training.
Are Officers required to complete a type-specific
ECDIS training course?
No but the company must ensure that their Officers are appropriately trained and familiarised with the equipment. This may be through a course or a program of onboard training.
Where is the vessel’s approval to use ECDIS as the Primary
Means of Navigation recorded?
On the vessel’s Record of Equipment, which is part of the Cargo Ship Safety
Equipment Certificate (where it is known as Form E) or the
Passenger Ship Safety
Certificate (where it is known as Form Pl
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?
Global Navigation Satellite
System (GNSS)
Which input enables the
ECDIS to generate a heading marker?
Gyrocompass
Which input creates the small triangles on the ECDIS screen which represent other vessels?
Automated Identification
System (AIS)
Which system input is used to display water depth and/or under keel clearance on the
ECDIS?
Echosounder
Which input provides the
ECDIS with STW data?
Speed log
Which system can be overlaid onto ECDIS and used for both position monitoring and assessing risk of collision?
Radar
Which two mandatory alerts relate to the vessel’s GNSS units?
Change in geodetic datum and positioning system failure.
How many mandatory alerts are there?
Five, although three additional ones may be raised either as an alert or an indication.
How many mandatory indications are there?
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 alert on an ECDIS?
Alarm, warning and caution.
What are the five mandatory alerts on ECDIS?
- Pass closer than the set distance from the safety contour.
- Deviation from route.
- Positioning system failure.
- Approach to critical point.
- Different geodetic datum.
Which electronic chart type is preferable when navigating with an ECDIS unit?
An Electronic Navigational
Chart (ENC)
Does a small-scale chart represent more or less land/sea area?
More. A small-scale chart uses a smaller scale to represent more land/sea area on a single chart.
Which scale is an ENC at scale
6?
Berthing
What is an ECDIS called when it is being used to display
RNCs?
A Raster Chart Display System
(RCDS)
Which electronic chart type enables the interrogation of chart data?
ENCs
Which electronic chart type is a database of information which is then represented graphically to the user?
ENCs
Which electronic chart type can make it easier to find information on berth names/numbers?
RNCs, because this
information is often harder to find on ENCs and can be laid out less clearly.
Which set of ECDIS symbols looks 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 ENCs?
- General
- Navigational Aid and Services
- Topographical
- Hydrographical
Which category of symbols contains depth sounding?
Hydrographical
Which of the contours takes into account a ‘Minimum UKC value?
Safety Contour.
Which Chart Presentation
Mode contains the least chart information?
Base.
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?
Deep 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’s no-go area, broadly dividing areas of safe and unsafe water in a way that’s very obvious and also works with the alarm features of ECDIS. Safety Depths give 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?
Clicking 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 screen.
Which scale/zoom level 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 feed 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 ECDIS systems?
S-52
Which is the current version of the Presentation Library?
Version 4 - 2017
What are the four ENCs standards?
5-52, S-57, S-63 and S-100
What is the difference between S-57 and S- 100?
S-57 is a single standard which defines the procedures to construct an ENC, whereas S-100 is a Universal Hydrographic Data Model which will enable a variety of S-100-based products (such as S-102 - Bathymetric Surface, i.e. depth information) to be overlaid on top of S-101, the new S-100-series standard for ESPCs.
We have a vessel that is 336m in length, anchored with 8 shackles on deck. What radius should the swinging circle be set toß
0.3 nm (3 cables)
What are VDRs used for?
To record data from various systems during a voyage so that this information can be accessed in case of an accident, much like the black box on a plane. S
How many metres are there in a shackle?
27.5m
How many GPS satellites must be in sight of the receiver unit in order to provide a 3D fix?
4
Under SOLAS, which vessels are required to carry a GNSS unit?
All vessels on international voyages, regardless of size.
Which was the original GNSS system?
The American NAVSTAR
Global Positioning System
(GPS).
What is an advantage of
GLONASS over GPS?
GLONASS’s 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?
In latitude & longitude.
What does a GNSS give speed in reference to?
GNSS speed is always Speed
Over Ground.
Is a more accurate position fix indicated by a smaller or larger
DOP value?
Smaller
How does RAIM work?
For receivers using the
NAVSTAR GPS constellation, it uses additional satellites that are within range to cross-check the integrity of the position data.
What is SBAS?
Space Based Augmentation
System.
What is the current status of dGPS in the UK?
dGPS was the primary form of Ground Based Augmentation
System 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 source of interference is the deliberate substitution of a genuine position signal with a fake one?
Spoofing.
Which error can occur when the GNSS signal bounces off of a vessel’s funnel before being received by the antenna?
Multipath error.
How does the radar understand the bearing of detected objects?
By reference to the vessel’s heading.
What size vessels are required to carry an X band radar?
Over 300gt.
Why must the first radar carried by a vessel be an X band?
Because only X band radars are able to detect SARTs.
What size 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, so it’s best to have one 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
A radar must ensure that targets can be detected while the vessel encounters a roll of up to how many degrees?
Within 1 degree.
What are the requirements for range discrimination of a radar?
In calm conditions, on a range scale of 1.5m or less, the radar must be capable of displaying two point targets on the same bearing, separated by 40 m in range, as two distinct objects
What are the requirements for bearing discrimination of a radar?
In calm conditions, on a range scale of 1.5m or less, the radar must be capable of displaying two point targets at the same range, separated by 2.5° in bearing, as two distinct objects.
When should you conduct a performance monitor on your radar?
On start up & 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?
B - R - G- T - Rain then Sea Clutter
How should the gain be set for optimum performance?
It should be increased slowly until a light speckling appears across the entire radar screen and then decreased ever so slightly until the speckling disappears.
What should the performance monitor result be checked against?
The image in the
manufacturer’s instructions.
Which speed input is used with a sea stabilised radar?
A speed log, giving the vessel’s speed through the water (STW).
In open sea, why is sea stabilisation of the radar preferred for collision avoidance?
Because the true vector of the other vessel will give a more accurate representation of the other vessel’s aspect.
In coastal or pilotage waters, why may ground stabilisation of the radar be preferred?
Because ground stabilisation 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 clearer visual indication of our vessel’s set and drift by displaying 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 stabilised?
Head Up.
Which error causes multiple targets at the same bearing but different ranges?
Multipath error
How much sea and rain clutter should be applied on our radar?
The minimum necessary to achieve a usable image. We should not attempt to have a
‘clean’ radar screen.
Which error results from additional, weaker radiation emanating from the radar scanner?
Side-lobe error
What causes indirect echo error?
What causes indirect echo error?
What is likely to occur in a vessel’s blind sector?
Targets will not be detected and acquired targets are likely to be lost.
Which may be more accurate, especially on smaller vessels; radar ranges or bearings?
Radar ranges, due to the beam width causing poor bearing discrimination.
How many lines of position must be used for all position fxes?
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/ECDIS.
Which MGN gives guidance on the use of electronic navigation aids?
MGN 379
Your Pl is set off of a headland to starboard of your track, at 3.6m. If the Pl is to seaward of the headland (i.e. over the water, not the land), are you to port or to starboard of your track? go
To port
Why is parallel indexing referred to as a ‘real-time’ method?
Because it enables continuous monitoring of the vessel’s position, as opposed to fixes which are always historic.
Which technique is used to help the OOW monitor the cross-track distance?
Clearing ranges.
Which technique is used to help ensure that the vessel stops at the required point?
Dead ranges.
When should Pls 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 a SART located in relation to the twelve dots?
At the first dot.
Which type of radar can detect
SARTs?
Only X band radars can detect
SARTS.
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 need to wait before taking decisions based on ARPA data?
Three minutes.
What size vessels are required to carry an ARPA?
Vessels over 10,000gt.
What does ARPA stand for?
Automatic Radar Plotting Aid
How many targets should an
ARPA be capable of tracking simultaneously?
40
Which system is used to assist the OOW with manual plotting of 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 manoeuvre’?
Automatic Radar Plotting Aid
(ARPA).
How quickly is ARPA required to provide preliminary CPA and TCPA data?
Within one minute.
How quickly must the ARPA provide accurate CPA/ТСРА data on which collision avoidance decisions can be made?
Three minutes.
Which data remains reliable even with a gyro error or failure?
CPA/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 the least, 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 vessel’s 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 errors 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 un-stabilised head-up orientation.
Which mode gives us a prediction of the future movement of another vessel in relation to our vessel?
Relative vectors.
Which mode gives us a historic representation of a vessel’s actual motion?
True trails.
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).
How often does Class A AIS transmit dynamic information for a vessel alongside?
Every 3 minutes.
Under the Workboat Code, which vessels are required to carry an AlS unit?
Those operating more than
20nm from land
Passenger vessels on international voyages are required to be fitted with which class of AIS?
Class A.
What is voyage information?
Information relating to the current voyage of the vessel, such as destination, ETA and draft.
What is dynamic information?
Information about the vessel which is constantly changing, including the speed, course, position and heading.
What is static information?
Information that is not subject to change, such as the vessel’s name, call sign, IMO number, dimensions and type.
Over which band do AlS units transmit?
Very High Frequency (VHF).
Which MGN outlines the procedures for the appropriate use of AIS?
MGN 342
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.
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.
What is an MKD?
Minimum Keyboard Display.
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.
How often does an AIS SART transmit each of its eight distress messages?
Once a minute
Which type of AIS ATON is physical object but has it’s AIS message transmitted from ashore?
A Synthetic AIS ATON.
Which type of AIS ATON does not physically exist?
A Virtual AIS ATON.
Which pole does a magnetic compass point towards?
points towards magnetic North Pole
Which vessels are required to carry a magnetic compass onboard?
All vessels
At which pole does the magnetic field exit the Earth’s surface?
The gimbal.
Which vessels are required to carry a spare magnetic compass?
出
Vessels over 150gt, if they aren’t fitted with an approved gyro compass.
What are the cardinal points?
North, South, East and West.
Which pole moves slowly over time; Magnetic or True
The magnetic poles move slowly over time. True north is a fixed, geographical point.
Calculate the compass error if the variation is 7°W and the deviation is 3°E.
4° West
Which type of magnetism changes with the vessel’s latitude and heading?
Induced magnetism.
What is metal which acquires permanent magnetism also referred to as?
Hard iron.
How can the OOW check the deviation that they should expect on a particular heading?
By reference to the vessel’s deviation card.
Which changes slowly due to the movement of the Earth’s magnetic poles; deviation or variation?
Variation.
On a paper chart, how is the variation in a location quantified?
The centre 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.
Which type of compass corrector corrects for induced magnetism in the ship’s funnel?
Flinders bar
Who is qualified to swing a magnetic compass?
In the UK, only a Compass
Adjuster holding the appropriate Compass
Adjuster’s Certificate of Competency may adjust a 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.
Which magnets correct for permanent magnetism in a longitudinal direction.
Fore & aft correcting magnets.
Which body is typically used to take an amplitude for the purpose of checking the compass error?
The Sun
How can the Line of Berth be used to conduct a compass error?
If alarge vessel is firmly alongside a straight berth, the vessel’s heading can be compared to the Line of Berth from the chart.
How often should the compass error be checked?
Ideally, the compass error should be checked once per watch and after each major course alteration.
Which method of controlling a gyro changes the gyro’s path from a circle to an ellipse?
Which method of controlling a gyro changes the gyro’s path from a circle to an ellipse?
What size vessels should carry a gyrocompass?
Vessels over 500gt on international voyages
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.
Aside from the Bridge, where else must a gyro repeater be fitted?
In the Steering Gear Flat, for use when emergency steering.
Calculate the true bearing:
Gyro bearing = 095°(G)
Gyro error = 1.5° Low
096.5°(T)
Which factors will increase speed error?
A higher vessel speed, a higher latitude and a more
northerly/southerly course.
Calculate the gyro bearing:
True bearing = 311°(T)
Gyro error = 0.5° High
311.5°(G)
What is lubber line error?
The error caused when the gyrocompass isn’t perfectly aligned with the vessel’s centreline.
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.
How many rings of optical fibre are used to make a fibre-optic compass?
Three, one for each axis.
What are the carriage requirements for fibre-optic compasses?
There is no carriage
requirement for fibre-optic compasses but SOLAS V R19 does permit them to be carried in lieu of gyro compasses.
When is the voltage induced in the two sensing coils the same?
When the fluxgate compass is aligned with the Earth’s magnetic field
How are fluxgate compasses used on large vessels?
To provide Rate of Turn data.
Before using a pelorus to take a relative bearing, what two things must the OOW align?
The bearing plate with the ship’s head.
What is the azimuth mirror used for?
To take bearings of the sun or other obiects that are above the horizon.
What must an azimuth ring be fitted to before it can be used?
It must be fitted to the magnetic compass bowl or gyrocompass repeater.
Which speed log works by detecting the change in frequency of the returning signal?
A doppler log.
Which type of speed log is commonly fitted to smaller vessels?
An impeller.
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 two and multiplied by the speed of sound in water to give the distance.
What is the speed of sound in water?
varies due to a range of different factors but, for depth sounding purposes, we assume that it travels at 1500 metres per second.
What is a double Janus configuration?
When a speed log transmits pulses fore/aft and athwartships.
When an echo sounder is exhibiting second trace echoes, 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.
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 the water). Non-Janus doppler logs can also be affected by rolling, yawing and pitching errors.
What is Pythagoras error?
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.
How can trim affect the 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.
Which autopilot mode does not rely on a GNSS input?
Heading mode
Which vessels should be fitted with an autopilot system?
Vessels over 10,000gt, although autopilots are commonly fitted on vessels of all sizes.
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.
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.
What is the drift angle?
The difference between the heading and the course over the ground, expressed in degrees.
If the OOW encounters a gyrocompass failure whilst using the autopilot, what is their first action?
Engage hand steering.
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 minimises steering inputs in bad weather. This can result in better heading-keeping, prevent unnecessary wear and tear, and decrease fuel consumption.
How will GNSS failure affect a trackpilot?
Trackpilots use GNSS inputs 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.
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.
Before engaging hand steering, in which position should the helm be?
Amidships.
What is yawing?
An oscillation in direction or heading, either side of the desired yalue.
What should happen immediately after hand-steering is engaged?
The crewmember should apply a couple of degrees of helm each side to ensure that they have control and that the rudder is responding appropriately.
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.
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.
Where is the ‘fixed’ VDR storage unit required to be mounted?
The ‘fixed’ storage unit must be mounted securely to an external deck of the vessel, so that it can be recovered by divers or a Remotely Operated Vehicle (ROV). A separate storage unit is required to float-free.
Which vessels are required to be fitted with a BNWAS?
A Bridge Navigational Watch
Alarm System is required to be fitted to cargo vessels over 150gt and all passenger vessels, irrespective of size.
How is the ‘float-free’VDR storage unit meant to be located once it has detached from the vessel?
It must be capable of
transmitting a locating signal, similar to that used by an EPIRB.
Which vessels are required to be fitted with a VDR?
All cargo vessels over 3000gt and all passenger vessels, irrespective of size.
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.
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 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 crewmembers, such as an all-Officer call or alarming in the crew mess.
