ECDIS, ENC's etc.

Question 1

Alarms required on ECDIS?

Answer 1

• Crossing Safety Contour
• Malfunction of ECDIS
• Deviation from Route
• Area with special conditions
• Positioning system failure
• Approach to critical point
• Different Geodetic Datum

Question 2

Each of following chart types, name the corresponding mode that the equipment is operating?

• Approved ECDIS equipment operating with ENC’s
• Approved ECDIS equipment operating with RNC’s
• Approved ECDIS equipment operating with unapproved Vector charts

Answer 2

• ECDIS Mode
• RCDS Mode
• RCDS Mode

Question 3

Outline the operational limitations of ECDIS equipment operating with RNC’s when compared to ECDIS equipment operating with ENC’s?

Answer 3

o Unlike ECDIS where there are no chart boundaries, chart boundaries are shown on Raster charts making transition between charts not so seamless
o Raster navigational chart (RNC) data does not trigger automatic alarms (e.g. anti-grounding). Some alarms can be generated by the user information. Including:
- Clearing lines
- Ship safety contour lines
- Isolated dangers
- Danger areas
o Horizontal Datums and chart projections may differ between RNCs. In some instances, this can appear as a shift in position.
o chart features cannot be simplified or removed to suit a particular navigational circumstance or task at hand. This could affect the superimposition of radar/ARPA;
o Without selecting different scale charts, the look-ahead capability may be somewhat limited
o Orientation of the RCDS display to other than chart-up, may affect the readability of chart text and symbols
o It may not be possible to interrogate RNC features to gain additional information about charted objects
o It is not possible to display a ship’s safety contour or safety depth and highlight it on the display, unless these features are manually entered during route planning
o Different colours may be used to show similar chart information.
o An RNC should be displayed at the scale of the paper chart. Excessive zooming in or zooming out can seriously degrade RCDS capability
o Mariners should be aware that in confined waters, the accuracy of chart data (i.e., paper charts, ENC or RNC data) may be less than that of the position-fixing system in use. This may be the case when using differential GNSS. ECDIS provides an indication in the ENC which allows a determination of the quality of the data.

Question 4

ECDIS and ENC’s - How is information stored?

Answer 4

The information is stored as ENC data in IHO S-57 format encrypted according to IHO S-63 security scheme

Question 5

ECDIS and ENC’s - How is information displayed?

Answer 5

The ECDIS system converts the ENC data to the System Electronic Navigation Chart for display and integrates the vessel’s position information from the Global Position System. The user can select the data to be displayed according to the circumstances. The density of data is appropriate to the scale of the chart.

Question 6

ECDIS and ENC’s - State precautions that should be observed when OOW selects the type of data to be displayed?

Answer 6

The data selected must be appropriate to the part of the passage. Sufficient safety information to enable a safe passage. Avoiding information overload.
Items to consider: 
-	Safety settings and alarms
-	Safety contours
-	Look ahead and alarms
-	Cross Track Distances
-	Scale of display
-	Density of information displayed such as depths
-	Display palette

Question 7

Key points in MGN 285 regarding the use of risk assessment when operating ECDIS in the RCDS mode?

Answer 7

1. Define the hazard
2. Calculate the risk
3. Decide if the risk is tolerable
4. Control the risk and record procedures
5. Review the risk and develop emergency procedures.