What are ECS and ECDIS?
Electronic chart systems (ECS) encompass many electronic systems that display digital chart data. The chart data can be vector or raster. No specific format is currently defined, although many ECS can use NOAA ENC data. The Radio Technical Commission for Maritime Services (RTCM) has published Standard for Electronic Chart Systems, RTCM 10900.7. The USCG now allows most commercial vessels on domestic voyages to use an ECS with NOAA ENCs for navigation without paper charts.
Use of an electronic chart display and information system (ECDIS) with ENC data is required for large commercial vessels on international voyages. ECDIS are certified to comply with several international standards, some of which are listed below.
- IHO Transfer Standard for Digital Hydrographic Data, IHO S-57
- IHO Specifications for Chart Content and Display aspects of ECDIS, IHO S- 52
- IMO Performance Standards for ECDIS, MSC.232(106)
- ECDIS - Operational and performance requirements, methods of testing and required test results, IEC 61174
How can I obtain NOAA ENCs?
You can download individual NOAA ENCs from the NOAA Chart Locator or by region from the ENC download page. NOAA ENCs downloaded directly from these Coast Survey websites are free.
NOAA ENCs may also be obtained from the International Centre for Electronic Navigational Charts (IC-ENC) through a Value Added Reseller. IC-ENC charges a fee for this service.
Why does the ENC look like gibberish after I downloaded and clicked on it?
Each ENC is a digital database that stores the NOAA nautical chart features and their location, shape, and attributes. They are published in the format of the International Hydrographic Organization S-57 Standard. They require an electronic chart system that reads and displays the data and are only intended to be used in their electronic form.
Historically, a sophisticated navigational computer called an Electronic Chart Display and Information System, or ECDIS, was required, however, ENCs can now be used on simpler electronic chart systems and chart plotters.
The NOAA ENC® Viewer provides a seamless display of NOAA ENCs similar to how the data is portrayed in an ECDIS, however please note that the viewer or images captured from them are not suitable to use for navigation.
For help getting started, refer to the Electronic Navigational Charts Online Viewer short video tutorial.
Is a NOAA ENC simply a copy of the paper chart?
ENCs were originally digitized from NOAA paper nautical charts. New source documents are now used to compile and maintain ENCs independently. Traditional NOAA paper nautical charts are no longer produced or maintained. The online NOAA Custom Chart application can be used to create custom paper charts derived from NOAA ENC data. Each custom chart is a static representation of the ENC data from which it is derived, while the digital ENCs have layers of data that can be turned on and off in the chart display and interact with the navigation system to provide warnings and alarms of dangers. The display of ENCs is also often simpler and less cluttered than the portrayal rendered on a paper chart.
What are the sources of data used to compile NOAA ENCs?
NOAA obtains data from a number of chart data sources. The primary ones are water depths and the identification of wrecks, rocks, and other obstructions from NOAA's Hydrographic Surveys Division, depths within federally maintained channels from the U.S. Army Corps of Engineers, delineation of shoreline from NOAA's National Geodetic Survey, and positions, types, and characteristics of aids to navigation (buoys, beacons, and navigational lights) from the U.S. Coast Guard.
How current are the NOAA ENCs?
All NOAA ENCs are under continuous maintenance. As new source data is received by NOAA, it is evaluated, compiled, and released to the public every weekday evening. This includes relevant USCG Local Notice to Mariners and NGA Notice to Mariners.
Our NOAA Navigation Updates Application visualizes where critical corrections to charts have occurred over a given time period for a specific area.
What hardware and software is required use NOAA ENCs?
Display of NOAA ENC depends on navigation software such as an ECDIS, which conforms to international standards. However, the NOAA ENC is not dependent on unique operating systems or navigation software. Since it is provided in a standard format, any navigation software company choosing to support NOAA ENC data can create applications that use it.
There are a wide variety of navigation apps and programs that use NOAA ENC data. While some use ENCs in their native format, many producers have put this ENC data into their own proprietary format. As a result, they control how and when NOAA chart updates are incorporated into their program. We encourage all mariners to make sure they understand how NOAA updates are incorporated into the specific application they decide to use.
Does NOAA provide any ENC viewing software?
The NOAA ENC® Viewer provides a seamless display of NOAA ENCs similar to how the data is portrayed in an ECDIS. The NOAA Chart Display Services portrays NOAA ENC as it would appear on a traditional paper nautical chart. Neither of these viewers or images captured from them are not suitable to use for navigation.
A brief video tutorial on using this tool is available on NOAA's YouTube site here: https://www.youtube.com/watch?v=SgIrHCbSBY0
What does the date entry mean on the NOAA ENC download page?
Each ENC has an Update Application Date, an Issue Date and various Cleared Dates. For more information, see ENC dates.
Do NOAA ENCs have edition numbers?
Yes, every NOAA ENC starts with a file header that contains information about that particular ENC, including edition number, issue date, and update application date.
What other files are included with the NOAA ENC?
CATALOG.031 - lists of the cells and ancillary files that are included in an NOAA ENC "exchange set."
README.TXT - lists all of the NOAA ENCs with their corresponding paper/raster chart number, title and other information.
Ancillary files - text files that are analogous to chart notes on paper charts or possibly information from the United States Coast Pilot®.
Image files - a picture that links to a feature(s) on the NOAA ENC, such as a picture of a bridge.
What is the difference between the NOAA ENC and the Digital Nautical Chart (DNC™)?
They are both vector format charts. However, the NOAA ENC is based on the International Hydrographic Organization Transfer Standard for Digital Hydrographic Data, Publication S-57 and is approved by the International Maritime Organization for SOLAS class vessels to use for navigation in ECDIS. The DNC is based on the Vector Product Format Standard, which is a NATO standard for digital military map and chart data. More information about DNCs can be found at the National Geospatial-Intelligence Agency.
What is rescheming? Are you changing the NOAA ENCs?
NOAA's Marine Chart Division is actively rescheming and improving NOAA ENCs to create a new layout of rectangularly shaped charts at a set of consistent scales. This effort will result in a more consistent suite of coverage with improved detail in many areas. This will result in larger standard scale coverage and resolve discontinuities in adjacent ENCs. Our ENC Rescheming Status Interactive Map shows our current progress.
Where can I download data not for navigation i.e. for a chart basemap or backdrop?
Please refer to our GIS Data & Services page to learn how to download ENC data in alternate formats or to display ENC data seamlessly within a Geographic Information System
A brief video tutorial on using this tool is available on NOAA's YouTube site here: https://www.youtube.com/watch?v=SfH-fQQWM_w