Passage Planning ECDIS

Question 1

Factors to consider when passage planning on an ECDIS

Answer 1

When planning a passage on ECDIS, the 00W should:
• Be aware that the charted objects on an ENC are not more accurate or precisely
plotted than charted objects on the corresponding RNC or paper chart.
• Make sure that there is enough of a safety margin between charted hazards and the
ship’s intended route to allow for the accuracy and precision of charts.

Depending on the ship’s certification, ECDIS may be the primary tool for passage planning on board. Effective use of route planning tools, voyage notes and action points contribute to a comprehensive passage plan.
When using ECDIS for passage planning, the following factors should be considered:
• Availability of and access to the required up-to-date ENCs and RNCs for the intended passage.
• This should include identification of areas where ECDIS may need to be in raster chart display system (RCDS) mode and where paper charts might therefore be required MGN 285.
• If reusing a previous passage plan, the need to recheck the route to confirm that it remains safe and no changes are necessary.
• An appropriate large scale ENC or RNC should be used when planning a route.
• Making sure that any old or previous routes are removed from the display.
• The need to select chart symbols (pick report) on ENCs to get additional detailed
safety and navigational information.
• Applying a maximum acceptable cross track distance (XTD) to each leg of a route.
This should comply with any requirements in the SMS and be appropriate for the
area.
• Calculating safety depths and safety contours and setting them up in line with the
under keel clearance (UKC) requirements in the SMS.

• Setting estimated time of arrival (ETA) information manually or using route planning tools. If this is set incorrectly, it may affect tidal data and time dependent information for the route.
• Applying current and tidal data, if integrated with ECDIS and up to date, to the route.
• Checking information about the vessel’s characteristics and confirming it as correct. This includes details about draught (including any allowance for squat or additional
safety margins, turn radius and vessel dimensions).

Question 2

MGN 285

Question 3

Safety Depth

Answer 3

Safety Depth: Value set by the mariner that is used by ECDIS to portray soundings as black if they are equal to or shoaler than the value and gray if they are deeper.

Question 4

Safety Contour:

Answer 4

Safety Contour: A specific depth contour set by ECDIS. It demarks the boundary between “safe-water” and shallow water with an extra wide isoline and is used to give an alarm if the ship, within a time specified by the mariner, is going to cross the safety contour.

Question 5

CATZOC

Answer 5

Category zone of confidence (CATZOC)
In calculating the ship’s safety depth, it is also important to consider the category zone of confidence (CATZOC) values of the chart in use.
The CATZOC value highlights the accuracy of data presented on charts; with six categories, it informs the user about how far they can rely on the chart when planning a passage or conducting navigation.

Question 6

Route Checking

Answer 6

To avoid losing critical information, the passage plan should not be over-detailed and it should be available in a format that can be easily understood by the bridge team.
When the officer planning the passage has completed the berth-to-berth passage plan, it should be checked and approved by the Master. These checks should include a careful inspection of navigational charts to ensure that the route is appropriate and safe.
When checking a route on ECDIS, it should be visually inspected at optimum scale (1:1) for the ENC or ANC in use. When a route is plotted on an ENC, the ECDIS route scanning function should be used as well as a visual inspection. For the route scanning function to be effective, the ECDIS should be correctly set up with safety depths and contours reflecting UKC requirements.
When the route scanning function is used, the officer should check each item that may be raised by the scan. If necessary, the officer should amend the route as required.

Question 7

Monitoring a passage plan on ECDIS

Answer 7

Monitoring a passage plan on ECDIS
ECDIS is an effective tool for monitoring a passage as long as the following checks are made before departure:
• The correct passage plan is loaded on both the primary and backup ECDIS terminals
• The safety settings, particularly depth safety contours.
• Information from all sensors connected to the ECDIS is available and correct.
Particular attention should be paid to the availability of information from the GPS receiver, gyro compass and log and that backup sensors are providing the correct inputs.
When using ECDIS to monitor the ship’s passage, the OOW should consider:
• The capabilities and limitations of ENCs and RNCs
• The need to select individual chart symbols (pick reports) on ENCs to get more
detailed safety and navigational information.
• The need to manage the amount of information displayed on an ECDIS terminal to
avoid obscuring charted features and information, and the effects of information
overload.
• The potential for positioning or related errors. Every opportunity should be taken to
confirm the validity of a GNSS position with traditional fixing techniques. These
fixes should, whenever possible.
• Looking ahead or using an offset view can improve situational awareness.
• The display of relative or true vectors and the appropriate interpretation of them.
• The potential for software anomalies.
• The OOW should be aware that the charted detail on some ENCs/RNCs may not be as
accurate as the GNSS position of the ship on ECDIS.
• Over-reliance on ECDIS should be avoided, particularly if it prevents a proper look-
out from being maintained.