Electronic Chart Display and Information System (ECDIS)


 

Maris Ecdis900 Mk3

Maris Ecdis900 Mk10

Maris PC Radar Kit

Danelec DM-800E

Kelvin Hughes Manta Digital

Kelvin Hughes ECDISPlus

An Electronic Chart Display and Information System (ECDIS) is a computer-based navigation information system that complies with International Maritime Organization(IMO) regulations and can be used as an alternative to paper nautical charts.

IMO refers to similar systems not meeting the regulations as Electronic Chart Systems (ECS).An ECDIS system displays the information from electronic navigational charts (ENC) or Digital Nautical Charts (DNC) and integrates position information from the Global Positioning System (GPS) and other navigational sensors, such as radar and automatic identification systems (AIS). It may also display additional navigation-related information, such as Sailing Directions and fathometer.

Types of Electronic Charts

Not all electronic charts are in same format; many different formats exist for electronic charts. However, two major types are now in use on merchant ships, they are vector chart and raster charts. Raster charts (RNC), in fact, are scanned paper charts into the pictures with adjustment made suitable for display on the RCDS. This RNC is also known as Admiralty Raster Chart System (ARCS Charts) which produced by the British Admiralty.

Vector charts are digitized charts. Countries are producing unique digital charts based on their interpretation of IHO standards (i.e. S-57 standards)

 

Raster Chart (RNC)

Vector Chart (ENC)

Chart data is a digitized “picture” of a chart.  All data in one layer and one format.

With raster data, it is difficult to change individual element of the chart since they are not separated in the data file.

Chart data is organised into many separate files. It contains layer information to produce certain symbols, lines, area, colours, and other elements.

With vector data, it can change individual elements with additional data.

 

The differences between RNC/ARCS (RCDS) or (ECS) and ENC (ECDIS)

 

RNC (RCDS or ECS)

ENC (ECDIS)

Chart based system similar to paper charts.

Will not trigger automatic alarms.  Some alarm can be generated from user-inserted information.

Chart projection may differ between RNCs.

Chart horizontal datum relates to the datum of the position fixing system, may appear as a shift in position.

Feature cannot be simplified or removed to suit a particular navigational circumstance. This affects the superimposed of radar/ARPA picture.

Cannot select different scale charts.

May affect the readability of chart text and symbols.

Not possible to gain additional information.

Not possible to display a ship’s safety contour or safety depth.

Different colours may be used to show similar chart information.

Displayed at the scale of the paper chart.  Excessive zooming in or out can seriously degrade RCDS capability.

In confined waters, the accuracy of chart data may be less than that of the position fixing system in use.

No chart boundaries.

Will trigger automatic alarms.

 

Alarms/Warnings

ECDIS provide Warnings and Alarms.  It combines several different functions into one computerized system which is possible to provide alarms or display warnings (indication) when certain parameters are met or exceeded as determine by the navigator.

Types of Warning

1. Deviating from a planned route;

2. Approach to waypoints;

3. Failure of the positioning system;

4. Vessel crossing safety contour and;

5. System malfunction or failure etc.

When to use ECDIS or RCDS ?

As the ENC is developed and produced by countries, it is not distributed by one stop shops like the distribution of paper charts, hence ships using ENC and RNC is common nowadays.  Therefore ECDIS can operate in two modes:

The ECDIS mode when ENC data is used,

The RCDS mode when ENC data is not available.

Components of ECDIS

ECDIS represents an item of equipment consisting of hardware, software and data. Whilst a high performance PC or workstation installed in a console linked with other items of ship’s equipment, such as:

· Course to steer linked with Gyro compass

· Rate of turn linked with a turn indicator

· Speed and distance linked with log

· Ship position is fed from the GNSS/GPS

· Radar data overlaid from source of radar.

Advantages over Paper Chart

ECDIS is not only an adequate replacement for the paper navigational chart but also a system containing all information important for navigation. It reduces the time-consuming manual correction of paper charts.

The ECDIS display can be superimposed with radar images and with the radar targets of ARPA; and the vessel’s positions is continuously shown on the chart display and stored at regular intervals. Hence manual chart exchange is no longer required.

The elements of route planning in ECDIS are waypoints and leg lines to ensuring safe track keeping. The cross distance along the leg lines can be set for activation of the alarm if the vessel deviates from the scope of leg lines. ECDIS "knows" whether a vessel can pass safely through an area, on the basis of the vessel's information fed in.

The Risks of ECDIS

It should be noted that the ECDIS is only a tool that helps a mariner safely and effectively navigate a ship. One of the biggest risks with the transition to ECDIS is an over reliance in the information provided.

Limitation of ECDIS

There are some limitations of the ECDIS as followings:

1. Chart Accuracy

ECDIS provides the navigator with a tactical tool which incorporates a high accuracy positioning device. The navigator can "zoom" in on an ECDIS chart to a scale beyond the intended accuracy of the charted information.

2. Technical limitation of other devices

The accuracy is also depends on the technical limitation of other devices linked to the ECDIS, such as GPS, radar, etc. The mariner must be attentive to the source and accuracy of the position fixing device utilized by the ECDIS.

3. Information Overload

The mariner is cautioned to be wary of information overload and a very cluttered display screen. Information overload and a cluttered screen seriously degrade navigation safety for the mariner and could result in a "technology-assisted incident".

4. Familiarization of ECDIS

A mariner must invest time and effort to mastering the device prior to his first navigational watch. This will be crucial to the navigation safety of the vessel in the event paper charts are not required or available on the vessel.