SCAMIN
Scale Minimum
The SCAMIN value of an object determines the display scale below which the object is no longer visible on an ECDIS.
Purpose:
1. Reduce the amt of clutter displayed to the user.
2. To prioritize the display of objects. (Safety critical info may be removed.)
3. To improve display speed.
ECDIS CATZOC Accuracy
- reflects the depth accuracy and safety depth/ UKC (Vertical value)
- position accuracy (Horizontal value) for determining XTL.
If XTL not properly used or understood, it becomes a danger to the safety of navigation. - Settings must be defined for each leg, safety contour, safety depth, shallow contour, deep countour, XTL and look-ahead function.
For ease of reading, this can be interpreted as follows:
* 1. High accuracy depth information (ZOC A1 and A2), shown as 6 stars or 5 stars. (20m from charted position, 0.5-1m from charted depth)
* 2. Medium accuracy depth information (ZOC B), shown as 4 stars. (50m from charted position, 1m from charted depth)
* 3. Poor accuracy depth information (ZOC C, D and U), shown as 3 stars, 2 stars or Unassessed ‘U’. (500m from charted position, 2m from charted depth).
3 main factors of CATZOC allowance
- Sounding Depth Accuracy
- Sounding Position Accuracy
- Quality of the Survey
Look-ahead zone
Safety Frame or Anti-Grounding Cone
- angle or width
- vessel speed,
- proximity to navigational hazards,
- available sea-room,
- traffic concentration,
- geographical limitations
- manoeuvrability
- The parameters for the look-ahead zone should be planned appropriate for the vessel’s speed and manoeuvring characteristics.
- They should be set for each leg of the passage and should consider pevailing conditions.
- The look-ahead zone should be reassessed in CATZOC areas that have reduced position accuracy (such as B, C, D, U) to ensure the vessel has a sufficient safety margin.
- The look-ahead zone should be highlighted on the display.
Change of S-52 and Mariner’s Benefit (Presentation Library 4.0)
- Detection of Navigation Hazard.
- Ensure all ECDIS raise the required alerts in a consistent manner, reducing training needs and improving safety at sea.
- Reduce the number of alarms raised because of ECDIS safety checking.
- Detection of Special Condition area.
- Ensure all ECDIS raised the required alerts in a consistent manner, reducing training
needs and improving safety at sea. - Reducing the number of alarms raised because of ECDIS safety checking.
- Ensure all ECDIS raised the required alerts in a consistent manner, reducing training
- Detection of safety contour.
- The IMO ECDIS Performance standards state that rock, wrecks, and obstruction detected inside the safety contour should result in an indication on the ECDIS.
- Reduces the number of alarms on ECDIS, whilst ensuring that the mariner remains aware of danger as rock, wrecks and obstruction will be detected if they meet the “Detection and Notification of Navigation Hazard” criteria.
- Add new symbol to indicate where in the ENC feature with temporal attribute are located.
- Will allow mariner to quickly identify where feature that have temporal attributes are located, such as seasonal buoys, traffic separation scheme.
- Add name in Anchorage / Fairway / Publication.
- Anchorage area- display a name in ENC.
- Fairway – display of name in ENC
- Nautical publication – new visible presentation for the meta feature nautical publication
- Allow the mariner to navigate to an anchorage without the need to repeatedly interrogate each area on the ENC:
- Presenting the name of fairway on the ENC for quick identification of location.
- Presenting a graphical indication on the ENC to give mariner the ability to easily select the nautical publication feature using the pick report.
- Add time or date within the ECDIS to display.
- Will allow the mariner the ability to plan and check routes, viewing the condition they will encounter on a given date or time in the future.
- Add a new symbol “Indication Highlight-designed for warning and caution condition that require an indication highlight on the ENC.
- Clear and unambiguous presentation of feature that require an indication highlight.
- Added guidance on “hover-over” function for a limited number of ENC feature.
- If provided, the hover-over function speed up the process of ENC enquiry by the Mariner. The new guidance ensure that the hover-over function does not result in the ENC presentation becoming obscured.
- Standardized symbol has been added to identify where automatic ENC update have been applied.
- Ensure the mariner is aware of updates that have been applied automatically to their ENC.
- Standardization of the ECDIS pick report.
- Ensure all ECDIS present pick report information in a consistent manner, reducing training needs and improving safety at sea. - Display of complete tidal stream panel in ECDIS pick report.
- Provide the mariner with tidal data in a form that is like the paper chart. - Standardized viewing group name.
- Ensure all ECDIS use viewing group in a consistent manner, reducing training needs and improving safety at sea. - Turn isolated danger in shallow water on/off.
- In certain circumstances mariners must navigate across the safety contour, this change allows the mariner the flexibility to navigate in shoal areas with or without the isolated danger symbol displaying on the ENC. - Display of the shallow water pattern at night.
- Important feature in ECDIS as it because increasingly difficult to detect change in the ENC depth shades during night navigation.
Responsible navigational practices
It is the responsibility of Master and operators as per STCW code and SMS which includes:
- Variety of nav aids.
- Verification by radar.
- Understanding capabilities,
- Cross Track Limits
- Over scaling
- Safety contours and depth alarms.
- Whenever possible, use radar overlay and P.I techniques to monitor the ship and the planned track.
- Consider the CATZOC and the horizontal and depth accuracy.
Marine Order 27
For an electronic nautical chart, the owner must ensure:
- The owner of a vessel needs to ensure charts and pubs for the intended voyage are adequate and up-to-date.
- The owner of a vessel:
a) Officially issued.
b) Assessible by computer
i) Located on the Bridge.
ii) Available at all times to OOW
iii) Connected to the vessel’s main and emergency power supplies.
Performance Standards for ECDIS
(a) if installed on or after 1 January 2009, conform to performance standards not
inferior to those specified in the Annex to the present resolution.
(b) if installed on or after 1 January 1996 but before 1 January 2009, conform to
performance standards not inferior to those specified in the Annex to
resolution A.817(19), as amended by resolutions MSC.64(67) and MSC.86(70).
Presentation of information, the effective size of the chart presentation should not be <250mm x 250mm / 250mm diameter.
Usage Bands
- Overview
- General
- Coastal
- Approach
- Harbour
- Berthing
Components of ECDIS
SENC
System Electronic Navigational Chart (SENC) means a database, in the manufacturer’s internal ECDIS format, resulting from the lossless transformation of the entire ENC contents and updates.
* It is this database that is accessed by ECDIS for the display generation and other navigational functions, and is equivalent to an up-to-date paper chart.
* The SENC may also contain information added by the mariner and information from other sources.
Types of displays
- Base Display
- Min. set of info that must be displayed and cannot be removed.
- Shows:
- Coastline
- Own ship’s safety contour
- Isolated underwater dangers of depths less than the safety contour which lie within the safe waters defined by the safety contour.
- Isolated dangers which lie within the safe water defined by the safety contour, such as
fixed structures, overhead wires. - Scale, range and north arrow.
- Units of depth and height.
- Standard Display
- Info contained in Base Display and most of the info needed for nav.
- Display base
- Drying line
- Buoys, beacons, other aids to navigation and fixed structures.
- Boundaries of fairways, channels.
- Visual and radar conspicuous features.
- Prohibited and restricted areas
- Chart scale boundaries.
- Indication of cautionary notes.
- Routeing systems and ferry routes.
- Archipelagic sea lanes.
- Info contained in Base Display and most of the info needed for nav.
- All Other Information
- To display individual info on demand.
- Spot soundings.
- Submarine cables and pipelines.
- Details of all isolated dangers.
- Details of aids to navigation.
- Contents of cautionary notes.
- ENC edition date.
- Most recent chart update number.
- Magnetic variation.
- Graticule.
- Place names.
- To display individual info on demand.
ECDIS Safety Settings
Appropriate safety settings are important as values such as safety depth and safety contour needs to be set properly.
OOW should always verify display settings, alarms settings aand safety parameters settings.
Safety Depth, affects the display of soundings.
Safety Contour, highlights the boundary between safe and unsafe water.
Shallow Contour, highlights the gradient of seabed.
Deep Contour, highlights the area where own ship may experience squat.
ECDIS chart carriage requirements
1 Type-approved
2 Use up-to-date ENC.
3 Maintained so as to be compatible with the latest IHO standards.
4 Have adequate, independent back-up arrangements in place.
Hydrographic services
Contracting governments are to ensure that hydrographic surveying is carried out, to prepare and issue nautical charts, to promulgate notcies to mariers and to ensure the info is made available on world-wide scale as timely as possible.
Difference between raster and vector data.
Vector data uses X and Y coordinates to define the locations of points, lines, and areas that correspond to map features.
Raster data, on the other hand, uses a matrix of square areas to define where features are located. These squares, also called pixels, cells, and grids, typically are of uniform
size, and their size determines the detail that can be maintained in the dataset.
Vector data are excellent for capturing and storing spatial details, while raster data are well suited for capturing, storing, imagery.
Raster Charts
- Scanning technique is used to reproduce the image of the paper chart.
- Image is composed as a set of
pixels. - Computer doesn’t have any info on these pixels apart from
colour and position. (Don’t over-zooming.)
Advantages:
- User familiarity, same as paper chart.
- Same reliability and integrity.
- User cannot inadvertently omit any navigational
information from the display.
- Kept in step with paper charts.
- Lower cost of production.
- Easier to ensure quality.
- Same format for other publications.
- Wider availability (worldwide coverage).
Disdavantages
- Over zooming causes pixelization.
- Datum may or may not be WGS 84.
- User cannot customise the display.
- No additional information available, cannot be interrogated without
additional database.
- Inaccuracies of paper charts are also been transferred.
- Cannot be sensibly rotated.
- Larger memory requirements than Vector charts.
- Cannot directly provide indications, alarms or warnings.
Vector Charts
Intelligent form of digital geographic Data. An object representation is described by attributes and coordinates.
- Operator has control of the display – can turn on & off data as required
- Allows different symbols & shades to display the information.
Advantages
- Chart info is in layers which allows for selective data display.
- Chart data is seamless.
- Possibility of zooming without distortion.
- Can select safety contours.
- Indications/alarms can be given.
- Charted objects may be interrogated.
- Provides additional information.
- Objects may be shown with different symbols.
- File sizes are smaller.
- Chart can be easily rotated (C up).
- Chart data may be shared with radar and ARPA.
Disadvantages
- More complex than raster charts.
- More costly and takes longer time to produce.
- Worldwide coverage is still not achievable.
- More difficult to ensure the quality and integrity of the displayed data.
- Requires Training.
Depth Contours
Depending on the safety parameters, the display mode and the position of an object will be different.
E.g. Isolated Danger
