E = Electronic
C = Chart
D = Display and
I = Information
S = System
The definition of an ECDIS and its use is specified in IMO ECDIS Performance Standards (IMO Resolution A.817 (19) and Resolution MSC.232 (82)):
‘Electronic Chart Display and Information System (ECDIS) means a navigation information system which, with adequate back-up arrangements, can be accepted as complying with the up-to-date chart required by regulation V/19 & V/27 of the 1974 SOLAS Convention, by displaying selected information from a system electronic navigational chart (SENC) with positional information from navigation sensors to assist the mariner in route planning and route monitoring, and by displaying additional navigation-related information if required.’
ECDIS is thus more than an “electronic nautical chart”. Nautical charts are in fact presented electronically, but in principle all kinds of chart – aviation charts, street maps, railway maps, etc. – could be presented on a computer display using the same methodology. However, we shall restrict ourselves to comments on the electronic nautical charts. ECDIS was initially developed for shipping, and thus the use of both terms as synonyms is entirely justified.
BRIEF HISTORY OF ECDIS
The International Hydrographic Organisation (IHO) in the 80s identified that emerging computer technology and position fixing systems could provide a digital representation of the paper chart on a computer screen, along with real-time positioning and interfaces to radar and other navigation sensors. The IHO formed working groups to define the standards for data encoding and digital chart presentation.
The first standard, S-57, describes the data model, object and attribute definitions for charted objects, encoding guidelines, product specifications and data structure of the Electronic Navigation Chart (ENC). The second standard, S-52, describes the presentation of the colours as well as chart and navigation symbols for ECDIS.
The IHO also works closely with the International Maritime Organisation (IMO), to develop operational performance specifications and a rigorous type-approval test regime for ECDIS manufacturers
The new amendments to SOLAS Chapter V (Safety of Navigation) Regulation 19 ‘Carriage Requirements for Shipborne Navigational Systems and Equipment’ require mandatory carriage of ECDIS for certain new ships built on or after 1 July 2012 and a subsequent timeline plan for retrofitting ECDIS to existing applicable ships.
The Manila amendments to the STCW code have also been updated to complement the new ECDIS carriage requirements and include mandatory training for ships operating with ECDIS. The Manila amendments entered into force on 1 January 2012.
WHAT ARE THE COMPONENTS OF ECDIS?
ECDIS represents an item of equipment consisting of
- Software and
The Hardware of the ECDIS
Is generally a computer with graphics capability, a high performance PC or a graphics workstation installed in a console linked with other items of ship’s equipment. Thus, ECDIS obtains the course from the gyro compass, the rate of turn from the turn indicator, and the ship’s speed through water from the log (the ship’s “speedometer”). Key features are the links with the position sensors of the ship (transit satellite navigation system) and in particular with the GPS (global positioning system, a satellite based positioning system), supplying via the NMEA interface a constant stream of highly precise position data (NMEA National Marine Electronics Association; NMEA0183 Standard for Interfacing Marine Electronic Devices, data record). Even radar pictures can be superimposed, either as raw data from a rasterscan radar, or as synthetic ARPA (automatic radar plotting aid) radar information. The hardware should be type-approved and comply with the guidelines of International Electro-technical Commission.
Should be as the IMO Performance Stanadards [Resolution A817(19)] It consists of the user interface (UI) and the so-called ECDIS kernel, the software that makes it possible to read the data and display a chart. This software is also called ‘function library’. In addition to the chart picture, the user interface shows buttons and keys for operating the nautical chart.
Electronic navigational Chart (ENC) –There are two different types of electronic charts in use with ECDIS and all navigation officers and marine managers should be aware of their differences and limitations.
Electronic Navigational Charts (ENC), commonly referred to as ‘vector charts’, are layered with digital information enabling the mariner to electronically interrogate features on the chart such as buoys, navigational marks, traffic separation schemes (TSS) and safety contours with detailed information displayed for the user
ENC’s enable the ECDIS to set different types of navigational alarms to act as a warning to the mariner. These warnings are usually visual as well as audible to give a clear indication of any dangers that lay ahead. The navigational alarms can include such hazards as shallow depths, shoals and isolated dangers as well as minimum under-keel clearance (for example, anti-grounding alarm) provided the ships echo sounder has been integrated with the ECDIS, draught details and alarm parameters specified. Early warning alarms of approaching waypoints and alteration of course points, position fixing reminders and changing electronic chart alarms can also be specified within the alarm parameters. ENCs provide the mariner with a clear display of the navigational situation without distorting the chart display when reducing the chart scale.ENC must conform to IHO (International Hydrographic Office) S-57 standards.
Overreliance on ECDIS when using ENC data may prove dangerous if inadequate training and familiarisation has been given. Unfamiliarity with ENC data and ECDIS functionality may cause operator error. The International Hydrographic Office has issued a circular warning that ECDIS may not display some isolated shoal depths
when operating in ‘base’ or ‘standard display’ mode. As a result, route planning and monitoring alarms may not always be activated when approaching such dangers and may result in groundings.
Mariners must ensure their ECDIS display has been set-up properly to the circumstances and conditions so that it includes all information necessary for safe navigation. ECDIS display modes that are set-up in ‘base’ display mode may remove vital information.
WHAT ARE ADVANTAGES OF ECDIS?
- All chart information necessary for safe and efficient navigation is available at the click of a mouse
- Simple, reliable and fast updating of the ENC
- Reduces the navigational workload as compared to use of a paper chart
- It enables the mariner to execute in a convenient and timely manner
- Route planning
- Route monitoring
- Real-time position plotting
- Route and waypoint management
- Real time monitoring of vessel’s position by OOW
- Radar / ARPA can be superimposed for enhanced command action (Anti-collision)
- Anti Grounding Tool
- Weather and forecast data can be superimposed.
- Ice data can be superimposed
- Log keeping electronic and easy
- Voyage playback possible
- Real time update of chart possible
One of the most important features of ECDIS that makes it a unique aid to navigation, is the capability of generating alarms (anti-grounding, off route, etc.) based on input from sensors and analysis of chart information
The international standard for vector charts has been finalised by the International Hydrographic Organization (S-57, Version 3)
LIST OF ALARMS
- Under scale
- Exceeding XTE limits
- Crossing safety contour
Area with special conditions *
- Deviation from route
- Approach to critical point
- Different geodetic datum
- Malfunction of ECDIS
- Information over scale
- Larger scale ENC available
- Different reference system for added
- Navigational information
- Route planning across safety contour
- Route planning across specified area
- Positioning system failure
- Position test failure
*Area with special conditions includes Traffic separation zone,Traffic routing scheme crossing or roundabout, Traffic routing scheme precautionary area, Two-way traffic route, Deepwater route, Recommended traffic lane, Inshore traffic zone, Fairway, Restricted area, Caution area, Offshore production area, Areas to be avoided, Military practice area, Seaplane landing area, Submarine transit lane, Ice area, Channel, Fishing ground, Fishing prohibited, Pipeline area, Cable area, Anchorage area, Anchorage prohibited, Dumping ground, Spoil ground, Dredged area, Cargo trans-shipment area, Incineration area, Specially protected areas
What is the difference between Raster & Vector Electronic Charts?
A RASTER CHART
Is basically just a visual scan of a paper chart. It is a computer based system which uses charts issued by, or under the authority of, a national hydrographic office, together with automatic continuous electronic positioning, to provide an integrated navigational tool.
RASTER CHARTS are digitized by “scanning” the paper chart (using technology common in desktop publishing). Each tiny segment of each line on a chart is converted to a “raster” picture element or “pixel”. These pixels are similar to a television picture or magnified newsprint in that they appear as “dots” on a grid. That is where the raster chart stops: the pixels form images on a computer screen, but the computer is “dumb” about what the images mean.
A digital representation of a paper chart in a matrix-like scheme of pixels. This chart is created by scanning a paper chart
A VECTOR CHART
Is more complex. Each point on the chart is digitally mapped, allowing the information to be used in a more sophisticated way, such as clicking on a feature (for example, a lighthouse) to get all the details of that feature displayed.
Vector charts represent individual chart features with points, lines and polygons given through their coordinates and appropriate codes
Comparision between Raster And Vector Charts
Privately produced vector charts
|Official Raster (RNCs)|
|Generally a copy of the paper chart||An exact replica of the paper chart||All data merged into cells|
|A different image to the original paper chart is presented at all levels of zoom and scale||The same image as the paper chart is always presented. The chart is more equivalent to the paper chart than any vector chart including ENCs||No resemblance to the paper chart|
|Symbols and colour vary with manufacturer.||Symbols and colour are the same as the paper chart equivalent.||The IHO publication S-52 defines new colours and symbols for ENCs.|
|Accuracy, reliability and completeness vary with manufacturer||ENCs should be more accurate and reliable than the paper version.||A new operational regime is required|
|A new operational regime is required||The same operational regime as paper charts is followed.||A new operational regime is required|
- What are errors of ECDIS?
- Who approves the ECDIS?
- What are Limitations of ECDIS?
- What are ECDIS Back-Up Requirements?
- Difference between RCDS AND ECDIS?
- CURRENT IHO ECDIS and ENC STANDARDS?
- What to do in areas without official ENC coverage?
- What is ECS ( ELECTRONIC CHART SYSTEM)?
- What are RASTER Charts?
- What are the disadvantages of RASTER charts?
- What are the advantages of raster charts?
- What are the disadvantages of Vector charts?
- What are VECTOR chart?
- What are the advantages of VECTOR charts?