What is an ENC OR Electronic Navigational Chart ?

ENC stands for “Electronic Navigational Chart”.The term was originally introduced for digital chart data complying with the IHO chart data transfer standard S-57.

ENC means the database, standardized as to content, structure and format, issued for use with ECDIS on the authority of government-authorized Hydrographic Offices. The ENC contains all the chart information useful for safe navigation, and may contain supplementary information in addition to that contained in the paper, which may be considered necessary for safe navigation

By IMO definition ENCs can only be produced by or on the authority of a government authorised Hydrographic Office or other relevant government institution; however the term ENC is not protected and has been widely (and incorrectly) used by private organisations to refer to their own products.To avoid possible confusion the word “official” has been used as a prefix to ENC in this document.

ENCs are vector charts compiled from a database of individual geo-referenced objects from Hydrographic Office’s archives including existing paper charts

Official  ENCs have the following attributes:

  • ENC content is based on source data or official charts of the responsible  Hydrographic Office;
  • ENCs are compiled and coded according to international standards;
  • ENCs are referred to World Geodetic System 1984 Datum (WGS84);
  • ENC content is the responsibility of the issuing Hydrographic Office;
  • ENCs are issued only by the responsible Hydrographic Office; and
  • ENCs are regularly updated with official update information distributed digitally
  • An ENC is a digital chart produced by National Hydrographic Offices which complies with the IHO’s (International Hydrographic Organisation’s) S-57 Edition 3 product specification, which describes in detail the structure and format to be used by the Hydrographic Offices for the exchange of ENC (Electronic Navigational Chart) data between themselves, manufacturers and other users. In short, this is the specification for the electronic charts to be used in the approved ECDIS
  • An ENC contains all necessary navigational information, which is not shown on paper charts, e.g. characteristics of objects such as lighthouses, lights, bouys, etc. 
  • Official ENCs fulfil the IHO S-57/3.1 product specification and have the most recent updated data from originating National Hydrographic Offices. When used in an ECDIS, ENC data facilitates unique functionality that improves the safety of navigation at sea.INDERJEET SINGH