Ecdis Flashcards
What is ECDIS
Electronic chart display information system
It Is an aid to navigation which uses electronic navigational charts to display chart, passage and vessel information on a computer display
Requirements for ECDIS to be primary form of navigation
(x8)
- Type approved
- official up to date ENC’s
- must be maintained to comply with latest IHO requirements
- operators need to have generic and type approval training certificates
- Must be include in the Safety Equipment Certificate’s - Form E
- must have approved, independent, up to date backup system
- risk assessment needs to be completed
- onboard familiarisation training
What is a vector chart or enc
- Digital chart that is made up of different layers of digital information which can be displayed as a seamless chart
- Chart Information is contained in a database and can be displayed and removed as required.
- Developed with information supplied by approved hydrographic offices
- vector charts can be zoomed and will not pixelate.
What is a raster chart
- Rastor chart is a picture of a paper
- if zoomed in it will pixelate
- information can not be selected or deselected
- what you see is what you get
- very space consuming
What is a SENC
- A SENC is made up of information provided in the vector/enc chart so as to be displayed in the Brand/make of Ecdis system
- The SENC is specific to the make of Ecdis system.
Ecdis alarms
(x7)
- crossing safety contour
- XTE/deviation from route
- Approaching a critical point
- Area special conditions
- Malfunction of Ecdis system
- Position system failure
- different geodetic system
Ecdis indications
- larger scale ENC available
- Information over scale
- No ENC available
- Default Safety contour
- route planning across SAFTEY contour
- Route planning across specified area (prohibited area)
- Crossing a danger in route monitoring
- different reference system (i.e. Ft or meter)
- System test failure
- Customised display
What is IHO S52
International standard for enc Presentation library for chart symbols, objects, colors
What is IHO S57
Sets the standard format for Data transfer between the IHO, hydrographic offices, manufactures, software developers and end users of ECIDS.
Types of display
Base display
Standard display
All layers
Custom
What is contained in the base display
- Safety contour
- Coast line
- Isolated dangers that lie with in the safe area of the safety contour
- Iso dangers that lie in safe zone like bridges or overhead cables or bouys
- Traffic routing
- Scale range, orientation, display mode
- Units of depth
What is in standard/ default display
- all base info
- drying line
- AIDS to navigation (lights and bouys)
- boundaries of fairways and channels
- warning indications
- prohibited areas
- indication of cautionary notes
- visual and radar conspicuous features
- chart scale boundaries
What are the CATZOCS
Category zones of confidence
A1. +- 5m, extremely accurate, (6)
A2. +- 20m, Very accurate not as accurate as a1 (5)
All lower CATZOCS require additional safety margins
B. +-50mm, NAV Hazards not expected but may exist (4)
C. +- 500m low accuracy, depth anomalies may exist (3)
D. poor accuracy, severe depth anomalies may exist (2)
U. unsurveyed (1)
How to update ECDIS
Weekly update provide by the UKHO or a RENCS via a disk disk/USB or a direct download via Internet on to a separate computer and transferred to Ecdis system on a clean virus free sub drive
The weekly updates contain latest editions of charts and permanent corrections
Updates are made to the SENC and cannot be edited. The ECDIS system will log and record all updates that are made to the ENC.
How must NAVTEX and NAV warnings be entered into an ecdis
When NAV warnings are released via navtex or Inmarsat SAFTEY net they must be manually entered onto the chart sytem. They Ecdis system will indicate that they are manual corrections and may be deleted.
What is safety depth
A User set depth which is generally set as the same depth as the safety contour. Ecdis will display all soundings shallower than this depth as black/bold and all soundings deeper than this as grey.
What is a safety contour
User defined contour which indicate the boundary between safe and unsafe water. It is made up of the draught of the vessel + squat + a safety margin(minimum UKC)- height of tide.
If there is not a contour for the set depth the ECDIS unit will select the next deepest contour as the safety contour. If the vessel crosses the safety contour an alarm will sound. If the safety contour is crossed during route planning and indication will be displayed.
How do you determine the safety depth and safety contour depth.
Vessel safety = vessel draft + squat + safety margin (min UKC)
Static draft: the draft of the vessel when fully loaded and not making way.
Squat: the amount of squat that the vessel will experience at the maximum speed for that particular area
Safety margin: the minimum under keel clearance that is required by the vessels SMS
What is a shallow contour and how is it calculated
Shallow contour is the depth shallower the safety contour entered in by the user. It indicates the depth at which the vessel will ground. The area shallower than this will be Shaded dark blue.
It is calculated as the draft + squat
What is np133C
It is the admiralty ENC AND ECDIS MAINTENANCE RECORD
It provides a reference guide and record for use of Ecdis
It is used to record all enc software updates, annual performance checks, ,maintenance records
It assists with port state control inspections to ensure the vessels Ecdis system complies with SOLAS chapter 5
What are the differences between RASTER and VECTOR charts
- raster cannot be interrogated.
- raster must be displayed at scale of chart
- cannot zoom
- horizontal datum may be different to the Gnss datum
- raster will not trigger any auto alarms, may trigger user set alarms i.e. Clearing lines, isolated dangers, danger areas
- features on chart cannot be removed
- look ahead may not be as useful as depending on the scale of the raster chart you can only look so far
- changing orientation of the chart may effect readability of symbols and notes
- cannot display ships safety contour or safety depth
When can you use a RNC chart
When there is no enc available for that area. It must be backed up by either a risk assessment or an up to date paper chart
What is SCAMIN and SCAMAX
Scale minimum and scale maximum
SCAMIN is the levels of under zoom at which the Ecdis unit starts to remove certain features. Helps reduce screen clutter.
SCAMAX Ecdis starts to remove items when to far zoomed in
How are t and p notices displayed on the Ecdis display
They will have a red or green shaded area around them..
What is the Safety Frame function
Is either a vector(rectangle)or arc (cone) that lies ahead of the vessel and provides earlier warning of an approaching danger.
What MGN’s discus ECDIS.
MGN 285
MGN 360
MGN 379 use of electronic navigation aids
Whats is the deep contour.
It is the deepest depth at which the vessel will begin to experience squat. Usually about 2 x draft.
Limitations of ECDIS
- Over reliance
- Alarm Deafness
- Tendency fo operator to focus more on the ECDIS than out the window
- Incorrect Scale usage
- SCAMIN, Wrong scale ECDis will auto remove objects
- CATZOCS, not as obvious
- ECDIS programs differ in their functionality and operation
- ECDIS not updated correctly then may not be able to display symbols correctly
- Only as reliable as the info inputted. Bad Gps = Bad position,
- Screen clutter
- Users ability to remove information
How to know if ECDIS is up to date.
ECSIS Chart 1.
(DPPC) Data Presentation and Performance Check
Individual cell used to display a charts symbol key.
If ECDIS does not have the latest software and S-52 library installed symbols will not be displayed.
Records of updates to be entered into ECDIS and ENC Maintenace record
What is S-63
Data Security.
Piracy prevention: Prevent unauthorised use.
Selective access: Restrict access to cells that have been licensed
Authentication: To provide assurance that the information has come from an approved source.
