The use of ENCs within ECDIS.

06.08.2020

AVCS is available in S-63 Edition 1.2 format on DVD and via the Internet.

Notice of all known changes is usually given in ENCs (using updates or new editions) in advance of the implementation date by using the attributes Date Start (DATSTA) on new features that are being introduced and Date End (DATEND) on existing features that are being discontinued. The purpose of these attributes is to allow mariners to preview forthcoming changes and ECDIS to apply the changes automatically at the appropriate time.

ECDIS must be maintained to the latest IHO standards. The mariner can use ECDIS Chart 1 (a legend of the entire set of symbols that may be used within an ENC) to review the new symbols introduced in IHO S-52 Presentation Library Edition 4.0.

Positions obtained from Global Navigation Satellite Systems, such as GPS, are normally referred to WGS84 Datum. In many parts of the world, however, charts were originally produced on a variety of local datums for which the shift to WGS84 may be unknown or unreliable. ENCs derived from such charts may not be accurately referred to WGS84 Datum. This can result in small but noticeable positional differences that may be significant to navigation. The estimated values of the differences for these cells are detailed in the Information attribute of Caution Areas.

The UKHO's weekly updating service for ENCs includes the latest updates issued by all the contributing hydrographic offices. These updates may or may not be synchronised with Notices to Mariners and new editions produced for their national paper chart series. Mariners should be aware that the appearance and content of the data displayed in electronic charts may differ substantially from the same or similar data in paper chart form.

Most ENC producers include Temporary (T) and Preliminary (P) Notices to Mariners in their cells wherever possible, but where this is not the case mariners are advised to consult relevant T&P NMs published in Notices to Mariners bulletins or on the ENC producer's website.

Each object in an ENC has a Scale Minimum (SCAMIN) value. This determines the display scale below which the object must not be displayed by an ECDIS and reduces excessive information on the screen. Latest ECDIS standards provide a control on the ECDIS that overrides this SCAMIN display criteria. Mariners should use this during planning to see all the information along the track.

Some national languages, especially those that use additional character sets, e.g. Turkish, Korean, etc. cannot be viewed in some ECDIS equipment.

"Cancellation" is the term used when an ENC producer issues an update to cancel and delete a base cell.

"Withdrawal" is the term used when the UKHO decides to withdraw an ENC from ADMIRALTY services. There is nothing to prevent end users continuing to use the cell until their permit expires. While cells remain withdrawn they will not be updated and their carriage will not satisfy SOLAS requirements. The withdrawal of ENCs from ADMIRALTY services is communicated in the README.TXT file and Section VIII of the ADMIRALTY Notices to Mariners Bulletin. A full list of withdrawn ENCs is maintained in the Updates tab at https://www.admiralty.co.uk/digital-services/digital-charts/admiralty-vector-chart-service.

The issuing of temporary and preliminary information is considered an essential part of keeping navigational charts up to date. However, T&P NMs are produced for paper charts, not ENCs and not every ENC producer includes T&P NM information in their ENCs. The latest confirmed status of T&P NM information in the ENCs that are available in AVCS is shown in the ENC-TandP-NM-Status.pdf file available in the INFO folder on AVCS discs and the Updates tab at https://www.admiralty.co.uk/digital-services/digital-charts/admiralty-vector-chart-service. ADMIRALTY T&P NMs for paper charts are included in the ADMIRALTY Information Overlay (AIO).

To find out more, please read https://www.admiralty.co.uk/AdmiraltyDownloadMedia/AVCS/Important-Information-for-AVCS-users.pdf