1. ENC or ARCS, ECDIS or ECS? What is the difference?
  2. NAUDEQ Chart Service with ENC S-57 and ARCS
  3. NAUDEQ Chart Service: ENC Service
  4. Download ENCs

Navigators became sure of which type of electronic chart to select!

1. ENC or ARCS, ECDIS or ECS? What is the difference?

The IMO convention "Nav 44" ratified the use electronic navigation charts (ENC) base of official sources for as long as they met or exceeded the specification known as S-57. In this case, and provided that they were displayed on type-approved ECDIS software and hardware and utilising the ENC could be considered as paper-equivalent. This means actual replacement of the paper chart.

Electronic chart systems have for the last ten years used a variety of privately produced electronic charts mostly in vector format. The UK Hydrographic Office introduced an official and up to date electronic chart in raster format, the ARCS service. The same format was adopted by the Australian HO for their Seafarer service and in the US, NOAA have licensed official raster charts in the BSB format.

However, as a potential customer you must consider two principal aspects:

  1. Are my ECDIS software and hardware type approved?
  2. Are the navigational charts which I wish to use are in S-57 standard?



You must keep in mind, however, that the IMO expects that a suitable back-up system is in place in case of electrical or mechanical breakdown. This back-up system can be either a second ECDIS approved unit or a set of paper charts!!!
ECDIS approved systems comprise the type approved hardware: display, CPU, keyboard, trackball, back-up, console, UPS and operating system. Most ECDIS units are compatible with ARCS charts as well as S-57 charts because official S-57 chart coverage is still limited to Northern Europe and is likely to be some years before a decent worldwide coverage is available.


Alternatively, non-ECDIS display systems, known as ECS (Electronic Chart System) are available and can take two forms:


Types of electronic charts are available:

  1. Official ENC.
    These charts are official products commercialised through RENC. PRIMAR-STAVANGER in Norway who are currently consolidating data from the following countries: Denmark, Estonia, Finland, France, Greece, Latvia, Norway, Poland, Russia, Singapore & Sweden. IC-ENC c/o UKHO now consolidates data from Belgium, Germany, Greece, India, the Netherlands, Portugal, Spain, South Africa and the United Kingdom. Subscriptions include a year of weekly updates supplied on CD-Rom which can be sent at regular weekly intervals to the vessel or to your office for onward distribution. Other authorities are also developing ENC's and these include the Canadian Hydrographic service through NDI, the Japanese Hydrographic association & the Australian Hydrographic service. No doubt, over the course of time, further developments can be expected at national hydrographic services and we will keep you informed in our site.
  2. ARCS charts.
    These are raster charts produced by the UKHO and cover the same areas as the paper charts. Pricing is on an annual subscription basis and quantity discounts are available. The subscription price allows the use of the data and the updates for a 12 month period.
  3. Private sector of electronic charts.
    Several vectorised electronic charts are available through private-sector of manufacturers. NAUDEQ onboard systems are not working with this kind charts as not official chart data. All our onboard systems are working only with official chart data developed by national hydrographic offices.


NAUDEQ can offer a complete advisory and supply service for electronic charts!

2. NAUDEQ Chart Service with ENC S-57 and ARCS

The NAUDEQ Chart Service is working on the behalf of the global hydrographic office community to provide to our customers a worldwide official electronic charting solution that meets IMO Regulations. Where supported by appropriate official Electronic Navigational Charts (ENC) and official Raster Navigational Charts (RNCs) such as ARCS, can be used in our MASTER-DEQ type-approved ECDIS for primary navigation in the areas where ENCs are not yet available.

The NAUDEQ Chart Service combines the most accurate official vector (ENCs) and official raster electronic charts (ARCS) which are available to deliver from global electronic chart coverage. We provides ENCs where available and ARCS charts where ENCs are not yet. This IMO-approved combination with dual official chart formats enables to shipping companies to reap the benefits of ENCs while coverage is still growing. As new ENCs become available, they are automatically issued to NAUDEQ Chart Service customers, replacing their corresponding ARCS charts.

Dual use of ENCs and ARCS in ECDIS minimizes the carriage requirement for paper charts and delivers the optimum combination of electronic chart safety and functionality, worldwide.

Regulatory Situation

All ships irrespective of size shall have nautical charts and nautical publications to plan and display the ship's route for the intended voyage and to plot and monitor positions throughout the voyage; an electronic chart display and information system (ECDIS) may be accepted as meeting the chart carriage requirements of this sub paragraph.

IMO SOLAS Chapter V, Regulation 19, 2.1.5

What is "SOLAS"?

IMO resolution MSC.86(70) permits ECDIS equipment to operate in a Raster Chart Display System (RCDS) mode in the absence of Electronic Navigational Charts (ENC). When operating in the RCDS mode, ECDIS should be used together with an appropriate folio of up-to-date paper charts.

IHO Product Specification for RNC, Foreword

As an IC-ENC, PRIMAR STAVANGER distributor, we can provide a very fast response to requests by using onboard ECDIS/ECS to generate permits.

This can effectively mean that within few minutes we can provide a licence for additional charts on an existing licence. This licence, in the form of a short data file will E-Mailed to the vessel and will enable it to download the new charts required from the CD-ROM set on board.

New licences for a vessel that had not yet ENC/ARCS charts on board are also set up in minutes but the necessary BASE CD's need to be on board before the charts can be activated. These can be sent from Paris to any port around the world or get from any our agency or distributor.

Weekly Update CD-ROM is sent at regular intervals to a suitable port from nearest our agency or distributor where they can be delivered on board the vessel and help to installed.


3. NAUDEQ Chart Service: ENC Service

Electronic Navigational Charts (ENC) are official vector nautical charts that conform to IHO Specifications and produced by national hydrographic organisations which are designed primarily for use on Electronic Chart Display and Information Systems (ECDIS) to meet the needs of the commercial shipping industry. Electronic Chart Display and Information Systems display ENCs, and present all the information needed for safe navigation.

ECDIS displaying ENCs are recognised under SOLAS regulations as being capable of meeting the chart carriage requirements for international shipping. So, unlike other electronic charts, they may be used as the primary source of navigational information, in place of paper charts.

Only the national Hydrographic Office (HO) can produce or authorise the production of ENCs of its own territorial waters, for example, the United Kingdom Hydrographic Office. Mariners trading internationally will therefore grow increasingly used to using charts produced by a much wider variety of national HOs.

ENCs are the only vector charts that may be used for primary navigation in place of paper charts. When operating with ENCs, an ECDIS can be programmed to automatically trigger alarms to warn of impending dangers and provide significant benefits in terms of maritime safety, risk management, cost savings and other operational efficiencies.


The NAUDEQ Chart Service include ENC corrections are issued every week to ensure all subscribers have fast access to all safety critical information. Updates are provided on CD-ROM every week and include all Notices to Mariners, New Editions, Replacement Charts and Temporary and Preliminary Notices.


The NAUDEQ Chart Service brings together Electronic Navigational Charts (ENC) from a wide range of official sources. The NAUDEQ Chart Service are able to provide users with access to a geographical ENC Chart Catalogue to enable viewing and ordering of the latest ENCs, allowing users to select ENC coverage. Alternatively, an electronic catalogue showing global commercially available coverage is available from the The International Center for ENCs:


ENC coverage is sold in units, each approximately equivalent in size to a standard BA paper chart. A unit may contain one or more ENC Cells. To make purchasing easy, where possible each unit (regardless of producing nation or number of cells it contains) is sold at a standard price. Current prices per unit are listed below against the country that produces them. To additional information about price for ENCs we ask you to address to our Commercial department. Examples of ENCs price are indicated on appropriate RENCs.


4. Download ENCs

From this page you can download the latest ENCs Base and Update CD. The content of these CDs are encrypted and can only be viewed by compatible systems. Always use your latest set of permit keys to view the content of these CDs. Please contact commercial department for obtain the permits.
Please note that it will take some time to download the Base CD due to the big amount of data.

Click here for download last base or update CD