ENCs are the new generation of nautical charts, which, in time, will replace all paper charts when sufficient ENC coverage is in place. ENC data is vector based consisting of points, lines and area features with detailed attributes; and is organized into cells, each seamlessly merges with adjoining cells without overlap.

In order to display ENC and make use of the information it contains, ships have to be equipped with an Electronic Chart Display and Information System (ECDIS). ECDIS can be built by different manufacturers, but stringent standards are set to ensure that all ECDISs will be able to read ENCs as well as to perform certain specific functions that are considered essential for safe navigation. The following international bodies are involved in the standardization of ENC and EDCIS:

• International Hydrographic Organization (IHO)

IHO governs chart contents, updating and display. The two standards it sets are as follows:

S-52: Specifications for Chart Contents and Display Aspects of ECDIS

S-57: IHO Transfer Standard for Digital Hydrographic Data

• International Maritime Organization (IMO)

  IMO sets the ECDIS Performance Standards, the focus of which is on the navigational safety and functionality aspects.

• International Electrotechical Commission (IEC)

  IEC identifies and describes the performance tests for IMO-compliant ECDIS. The standard, IEC1174- Operational and Performance Requirements: Methods of Testing and Required Test Results, forms the basis for type approval of ECDIS.

Unlike static paper charts, the dynamic ENCs are versatile in their use for navigation. The following are some of the things made possible by the advent of ENC:

• Levels for displayed details

  The levels of details of information can be varied to suit prevailing situations or purposes. For example, a ship calling at a port can progressively increase the details of information displayed from the time when she is making a landfall to the time when she is approaching the pilot boarding station. With this functionality, unnecessary distraction caused by cluttering of the display can be greatly reduced.

• Alarm functions

  A particular contour can be defined as safety contour and give anti-grounding warning depending on the ship's nearness to it.

• Provision of additional navigation-related information

  Additional information for a charted feature pops up instantly, only when it is required, simply by a click of a button.

• Automatic updating of charts

  Perhaps this is one of the area where significant improvement is truly realized, in terms of safety of navigation and workload of ships officers, who are required to carry out chart correction duty in addition to their normal navigation duties. With this automatic updating capability, accurate and timely incorporation of chart corrections can be assured.

• Introduction of time-varying information

  It is possible that time-varying information, such as tidal levels, can be fed into the ECDIS so that actual depths in real-time are displayed instead of the charted depths.

• Interfacing with other navigational equipment

  The diagram below illustrates the possibilities of interfacing various essential navigational equipment with ENC.