ECDIS Flashcards

1
Q

Advantages of Raster Charts

A
  1. Global Coverage
  2. Familiar
  3. Fully approved
  4. Cheap
  5. Same areas
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2
Q

Disadvantages of Raster Charts

A
  1. Cluttered when zoomed out
  2. Different Scales
  3. Not Scalable
  4. No Grounding Alarms
  5. Not Seamless, has boundaries
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3
Q

Advantages of Vector Charts

A
  1. Intelligent can be interrogated
  2. Seamless & Scalable with no distortion when zooming
  3. Information layers may be added or removed
  4. Alarms & Indications
  5. Ability to monitor own ships Route
  6. Small file size when updating
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4
Q

Disadvantages of Vector Charts

A
  1. Expensive to produce
  2. Same survey data as paper
  3. Not all approved data
  4. Unfamiliar symbols
  5. Operator error
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5
Q

ECDIS: Alarms!!!

A
  1. Crossing safety contour
  2. Area with Special conditions
  3. Deviation from route
  4. Position system failure
  5. Approach to critical point
  6. Different Geodetic datum
  7. Malfunction of ECDIS
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6
Q

ECDIS: Indications!

A
  1. Default safety contour
  2. Information Overscale
  3. Larger scale ENC available
  4. Different reference system
  5. No ENC available
  6. Customised display
  7. Route planning across safety contour
  8. Route planning across specified area
  9. Crossing a danger in route monitoring mode
  10. System test failure
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7
Q

ECDIS: RCDS Mode, Alarms!!!

A
  1. Deviation from Route
  2. Approach to mariner entered feature, e.g. area, line
  3. Position system failure
  4. Approach to critical point
  5. Different geodetic datum
  6. Malfunction of RCDS Mode
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8
Q

ECDIS: RCDS Mode, Indications!

A
  1. ECDIS operating in the raster mode
  2. Larger scale information available, or Overscale
  3. Larger scale RNC available for the area of the vessel
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9
Q

Base Display

A

To be permanently shown on the ECDIS Display.

  1. Coastline (high water)
  2. Own ships safety contour
  3. Isolated underwater dangers of depth less than the safety contour which lie within the safe waters defined by the safety contour
  4. Isolated dangers, which lie within the safe water defined by the safety contour, such as fixed structures, overhead wires, ect.
  5. Scale, Range & North arrow
  6. Units of depth & height; and Display mode
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10
Q

Standard Display

A
  1. Display Base
  2. Drying line
  3. Buoys, beacons, other aids to navigation & fixed structures
  4. Boundaries of fairways, channels, ect.
  5. Visual & RADAR conspicuous features
  6. Prohibited & restricted areas
  7. Chart scale boundaries
  8. Indiaction of cautionary notes
  9. Ship routeing systems & ferry routes
  10. Archipelagic sea lanes
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11
Q

S52

A

IHO Approved standard for chart display information

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12
Q

S57

A

IHO Approved standard for electronic chart data format

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13
Q

S61

A

IHO standard information for raster charts

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14
Q

RENC

A

Regional electronic chart coordination centre

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15
Q

RCDS

A

Raster chart display System

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16
Q

ARCS

A

Admiralty Raster chart service

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17
Q

AVCS

A

Admiralty Vector Chart System

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18
Q

SENC

A

System Electronic Navigation Chart

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19
Q

ECDIS Mandatory Sensors

A
  1. GPS
  2. SPEED LOG
  3. GYRO
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20
Q

ECDIS Additional Sensors

A
  1. RADAR: RADAR Image Overlay (RIO)
  2. AIS
  3. ECHO SOUNDER
  4. VDR (VOYAGE DATA RECORDER)
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21
Q

What is a Safety Contour?

A

A depth contour that is displayed as a thick line separating safe water from shallow areas.

If not set, it will automatically set at 30m

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22
Q

What is a Safety Depth

A

The calculated depth of water we can safely navigate in. I.e. Draft+UKC+Squat
All Soundings less than that depth will be BOLD.
DEPTHS greater than the safety depth will be greyed out.

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23
Q

When are paper charts required to be carried onboard? (solas V reg 19, IMO res 232)

A
  • If there isn’t an independent fully compliant second ECDIS unit connected to the ships main and emergency power
  • If the ECDIS is not type approved
  • If the ECIDS is not using official ENC’s
24
Q

What alarms and indications would an ECDIS give? (5 mandatory and 6 warnings)

A

Alarms
- Crossing safety contour
- Approach to critical point
- Mandatory sensor failure
- Deviation from route
- Different Geodetic datum

Indications
- Default safety contour
- Information overscale
- Larger ENC available
- No ENC available
- Customised display
- System test failure

25
Q

Main difference between ECDIS, ENC, ECS and RCDS. What are the carriage requirements for these 3 systems. What paper backups would be required for each system

A
  • New passenger ships over 500 gross ton and cargo ships over 3000 gross ton are required to be fitted with ECDIS
  • ECDIS is a computer based navigation system which can be used as an alternative to paper charts.
  • ENC’s (electronic navigation charts) are an official database containing the chart data, which must meet the IHO S-57 and S-52 performance standards produced by an authorized hydrographic office. ENC’s contains all the chart information for safe navigation.
  • An Electronic Chart System is an unofficial chart display system as its data is not upheld to IHO standards. Does not meet SOLAS requirements
  • RCDS (raster chart display system) display raster navigation charts which are essentially copies of paper charts. They are unintelligent and are just an electronic means of displaying a paper chart. They are used when ENC’s are not available.
  • ECS and RCDS always require paper backups.
25
Q

Carriage requirements

A
  • ECDIS: ENC’s required, no paper charts if authorised as primary means of navigation
  • ECS: Paper charts required
  • RCDS: Paper charts required
26
Q

Define ECDIS

A
  • Electronic chart display and information system
27
Q

What is a SENC (5 marks)

A
  • A system electronic navigation chart is created when an ECDIS converts an ENC into its own internal SENC format. It is the equivalent of an up to date paper chart. ENC conversion to SENC’s are individual to each ECDIS manufacturer. The SENC may also contain other information added by the mariner.
28
Q

Describe what a display base is

A
  • Minimum set of information which must be displayed and cannot be removed from the screen
29
Q

List 6 types of information found on a display base

A
  • Coastline
  • Own ships safety contour
  • Units of depth and height
  • Scale, range and north arrow
  • Isolated underwater dangers which lie in depths less than the safety contour
  • Isolated dangers which lie within safe water
30
Q

What is a standard display

A
  • The information contained in the display base and most of the detail required for safe navigation. This is the minimum level in which can be used for navigation
31
Q

Name 8 things you would see on a standard display

A
  • Base display
  • Drying line
  • Buoys
  • Boundaries of fairways/channels
  • Visual and radar conspicuous features
  • Prohibited and restricted areas
  • Chart scale boundaries
  • Ship routing systems
  • Indication of cautionary notes
32
Q

What is integrity monitoring

A

Integrity monitoring is consistently checking the system is displaying the correct information. This can be done through
- Position fixing
- Echo sounder
- Compare gyro and mag compasses
- Radar overlay
- ARPA overlay on chartered features
- Track history

33
Q

What is a vector chart

A
  • A vector chart is visual representation of a database.
  • Every object has a digital value.
  • Data is grouped in layers
  • Chart is intelligent and can be customised
  • It is a smart chart in that I can be interrogated, information can be added and removed.
34
Q

What is a raster chart

A
  • Produced by scanning a paper chart
  • Image made up of pixels
  • Level of information is fixed
35
Q

Advantages of a vector chart

A
  • Seamless join between charts
  • Safety contour and safety depth can be defined and displayed
  • Alarms automatically defined when approaching defined or fixed dangers
  • Chart features can be interrogated
  • Can add or remove information
36
Q

Disadvantages of a vector chart

A
  • Different presentation for those used to paper charts
  • Yet to have worldwide coverage
  • Information necessary for safe navigation can be deselected by the user
  • Too many layers can be added, potentially obscuring information
37
Q

Advantages of a raster chart

A
  • Presentation familiar for existing users
  • All information for safe navigation is displayed at all times
  • Cannot remove safety critical information
  • Worldwide coverage
38
Q

Disadvantages of a raster chart

A
  • Cannot be interrogated
  • Chart display cannot be customised
  • When overlaid with other information it may appear cluttered
39
Q

3 ways to update an electronic chart

A
  • CD, online through download or email
40
Q

What are 5 marks you find in both IALA systems

A
  • Cardinal marks
  • Isolated danger
  • Emergency wreck mark
  • Safe water mark
  • Lateral marks
41
Q

How would know if you were in IALA A or IALA B

A
  • On approach to harbour in IALA A you would port hand lateral marks would be red, in IALA B they would be green.
  • You could check the areas covered online or look at the admiralty buoyage system book
42
Q

How does an ENC display

A
  • Electronic navigation charts would be displayed as a vector chart. This is an intelligent chart that can be interrogated, with information being able to be added or removed.
43
Q

Explain the differences between a safety contour and safety depth

A
  • Safety depth is the depth value selected by the mariner. Depths below this value will show in black, depths deeper than this value will show in grey
  • Safety contour is defined by the user but then moved to the next highest contour by the ECDIS. Crossing the safety contour will generate an audible alarm
44
Q

Three factors to consider when setting a safety contour

A
  • Ships draught
  • Under keel clearance
  • Height of tide
  • How close the depth contours are
45
Q

Identify symbols on a vector chart (generic isolated danger, sounding of low accuracy, outer limit to unofficial vector charts)

A
46
Q

How would weather and navigation warnings show on ECDIS

A
  • If values exceed pre-set limits then they show visually
47
Q

3 factors for setting a safety depth

A
  • Ships draught
  • Under keel clearance
  • Height of tide
  • How close the depth contours are
  • Where the officer would like to show safe and unsafe water
48
Q

State how you would notice an MSI on an ECDIS

A
  • As a box on the ECDIS display in the position where the MSI originated from
49
Q

State how you can show Maritime Safety Information on an ENC

A
  • Enter the information on the chart in the appropriate place using a Mariners Note
50
Q
  1. Describe the main differences between Vector and Raster Electronic Charts.
    (10 marks)
A

Vector charts; Database of information digitised in “layers”.
Raster charts: A scanned version of paper chart.

51
Q
  1. What are the advantages and disadvantages of Vector and Raster charts?
A

Vector
Advantages:
1. All charts are to same datum WGS84
2. Charts are seamless
3. Are intelligent and can be interrogated for individual information.
4. Fully scaleable
5. Can be displayed other than in “north up” orientation.
6. Layers can be edited to produce individual “user maps”.
7. Automatic warning of dangers available.
Disadvantages:
1. Not all Vector Charts are officially approved
2. Non traditional standard symbols can cause confusion.
3. traditional symbols available
4. Editing of layers can lead to suppression of information
5. Area coverage of vector charts available small

Raster:
Advantages
1. Looks like a paper chart.
2. Area coverage of Raster charts available world wide.
Disadvantages
1. Traditional format.
2. Differing datums/projections.
3. Charts are individual
4. Charts are not intelligent no access to individual information other than
what can be sighted on chart.
5. No automatic warning of dangers.
6. Only displayed in “north up” orientation.

52
Q

Describe the difference between Vector and Raster charts used in
electronic charts systems. (10 marks)

A

Vector: constructed in layers of information. Each item an individual entry.
Raster: Scanned version pf paper chart. All information in one file.

53
Q

What is understood by the term ‘Datum’ as applied to navigational
charts? . (10 marks)

A

The point from which the position of all information is plotted.
World Geodetic Survey 1984 (WGS ’84)is the standard for electronic
charts. Paper charts vary according to Survey.
Greenwich.
Newlyn.
Ordinance Survey
Etc.,

54
Q

Explain the difference between ECS and ECDIS. (8 marks)

A

ECS generic name for any piece of equipment capable of displaying any type or format of
electronic chart. Unless ECS ECDIS then cannot be used legally for navigation. (4)
Electronic chart display and information system. Type approved, running type approved
software.
Official ENCs
Capable of displaying information from SENC, position information from navigational sensors.
(4)

55
Q

If a radar target of a single navigational buoy is overlayed on the electronic chart and
does not coincide with the displayed position of the charted buoy, state 4 possible
causes of the error. (8 marks)

A

Buoy out of position.
Chart incorrect or out of date.
Ships position incorrect.
Gyro error.
Incorrect datum