ENC Direct to GIS Help

ENC Direct to GIS displays and allows downloading of NOAA ENC data in a variety of GIS/CAD formats, using web mapping services.

The NOAA ENC data are in International Hydrographic Organization (IHO) S-57 format, which is the data standard for the exchange of digital hydrographic data. Nautical chart features contained within a NOAA ENC provide a detailed representation of the U.S. coastal and marine environment. This data includes coastal topography, bathymetry, landmarks, geographic place names, and marine boundaries. Features in a NOAA ENC are limited in that they only represent the geographic region depicted in that particular ENC. Aggregating nautical features from all NOAA ENCs in the creation of GIS data results in a contiguous depiction of the U.S. coastal and marine environment.

Screenshot of ENC Direct to GIS Application Screenshot of ENC Direct to GIS Application. Note that some data will not display on-screen until you have zoomed in to the appropriate level. However, when extracting data, all selected data in the scale band will be extracted whether visible on-screen or not.
Default Extent The Default Extent button returns the user to the default extent.
My Location The My Location button allows the network to detect your physical location and zoom the map to it.
ENC Scale Band button The ENC Scale Band button located at the top right corner allows users to turn on and off layers at a particular scale band. Clicking the drop down arrow next to the scale band's name provides several functionalities, such as changing dataset transparency or reading about the description of the dataset.
Basemap button The Basemap button in the top right corner allows users to overlay the ENC data with several choices of base maps.

Arrow to open extendable inset The arrow in the lower right corner of the screen opens an extendable inset allowing users to quickly zoom to a specific area on the map.
Navigation Bar The left side of the screen contains the zoom in and zoom out buttons. This can also be accomplished via mouse wheel. Panning is accomplished via clicking in the map interface in the desired direction.
Data Extract Button The Data Extract button allows users to extract ENC data by scale band. Refer to the "How to Extract ENC data" instructions below for details.

Data Extract Button The Data Extract tool allows users to extract ENC data by scale band. The tool doesn't require the data to be visible on the screen. Users can extract data by drawing a polygon on the screen to define the area of interest. The ENC data will be clipped using this user-defined polygon. Users can select various output file formats, such as shapefile (.shp), geodatabase (.gdb), or various CAD file formats.

The following is an example of extracting data within the Overview scale band:

Step 1: Select your scale band

Data Extract Button

Click the Data Extract button to expand the six scale band choices: Overview, General, Coastal, Approach, Harbour, and Berthing Click Extract Overview.

Step 2: Select your geographic limits and data layers

Data Extract Button

    In the Extract Overview :

  • 1. Select area - select a shape and draw a polygon on the screen. This will be used as a boundary to clip the ENC data.
  • 2. Select layers to extract - check the boxes next to the layers that you would like to extract. The layers do not need to be visible on the screen to be extracted.
  • 3: Select file format - choose the desired output file format.
  • 4: Click the Extract button. If you ask to extract data from a feature layer that has no data, an empty layer will be created as output.

Step 3: Save your data

Save your Data

When the extraction is completed, the user will be prompted to save the output .zip file. The default output filename is 'extractedData.zip' - the user may rename it if desired. Please note that if the output .zip file is not renamed and another output .zip file is downloaded, the new output .zip file will override the previous output .zip file.

ENC Scale Band

    To view metadata for data layers:

  • 1. Choose the ENC Scale Band button and click the three dots on the right of the layer.
  • 2. Choose 'Description.'
  • 3. A new browser window will show the description for the map service. Click on a layer to see metadata for a specific layer.

ENC Direct to GIS provides services for each scale band in a number of formats.

Title Esri Map Service Esri Geoprocessing Service Web Map Service KML
ENC Overview icon icon icon icon
ENC General icon icon icon icon
ENC Coastal icon icon icon icon
ENC Approach icon icon icon icon
ENC Harbor icon icon icon icon
ENC Berthing icon icon icon icon

In addition, three specific theme layers can be viewed or obtained for the entire United States. These standardized data sets are based on several Federal Geographic Data Committee (FGDC) and Open Geospatial Consortium (OGC) standards.

Title ArcGIS Viewer REST Service Web Map Service KML Shapefile Metadata
Coastal Maintained Channels icon icon icon icon icon icon
U.S. Maritime Limits & Boundaries icon icon icon icon icon icon
Shipping Lanes and Regulations icon icon icon icon icon icon

How does data from ENC Direct to GIS differ from NOAA ENCs?

ENC Direct to GIS data is in a format not certified for navigation. The data is derived from the official NOAA Electronic Nautical Charts (ENC) through GIS conversion software.

Can I use ENC Direct to GIS for navigation?

No, ENC Direct to GIS is not certified for navigation. You can download NOAA ENC®s for navigation.

Where do all of the data layers originate?

The data layers have been created by merging S-57 object classes from all NOAA ENCs into seamless layers. For example, the coastline layer for the Harbour scale band is a composite of the S-57 object class COALNE from all current Harbour ENCs.

Where can I find information about the ENC Direct to GIS layers?

Use the free S-57 object catalog to look up layer and attribute definitions. (This service is for informational purposes only and does not constitute an endorsement by the U.S. Government.) In addition, you may click the 'Description' from the 'ENC Scale Band' drop down list for each scale band to get a list of available GIS layers.

How are the data layers organized?

The data layers are grouped in folders by thematic categories that describe the layers that they contain. ENC Direct to GIS contains more than 200 data layers, which are found by navigating through the appropriate folders/subfolders.

Why are some of the S-57 object classes separated into individual geometry layers (point, line, polygon)?

S-57 object classes contain multiple geometry types. For example, the WRECKS object class can contain point and polygon features. It is important to note that an S-57 object in ENC Direct to GIS can have point, line, and polygon parts.

Why can I only see certain layers when I am zoomed into a particular scale?

Layers are configured with scale dependency. The data is displayed by scale band. As you zoom in at certain scale ratio, the application will display ENC data compiled for that scale band. For example, if you zoom in at scale 1:36,112, the application will display ENC data within the Approach and Harbour scale band. If you would like to find out which scale band you are viewing, simply click on the screen and a popup window will appear displaying the current ENC name.

In addition, to speed up the map service and reduce data clutter in the map frame, the point layers for the Overview scale band are displayed at a smaller scale within the Overview scale range. The scale range for the Overview scale band is ranged 1:1,500,001 or smaller. The line and area features are visible with a minimum scale ratio of 1:4,622,324. The point layers are visible with a minimum scale ratio of 1:2,311,162.

What is the coordinate system for data used in ENC Direct to GIS?

Data used is in GCS-WGS 1984 coordinate system.

What is the map projection for ENC data?

The majority of NOAA charts use a Mercator projection, classified as a cylindrical projection upon a plane, the cylinder tangent along the equator. The Mercator is the most common projection used in maritime navigation, primarily because rhumb lines plot as straight lines.

All ArcGIS services and basemaps are stored with a continuous tiling system to support the seamless display of map data for large scale subareas. This requires a single map projection for the world. The spherical Mercator projection is used. This is often referred to as the WGS 1984 Web Mercator [Auxiliary Sphere] projection.

How long will it take to download my data?

The time varies and depends on your Internet connection and the amount of data you wish to download. Downloading layers that have a smaller spatial extent is generally quicker than downloading layers for a large spatial extent.

When extracting data, how many scale bands do you recommend?

We recommend selecting one scale band per extraction. If you select more than one scale band during the extraction process, you will obtain duplicate data at different resolutions. We recommend selecting the best scale band for the type of application for which you require the data.

When drawing multiple areas for extraction, does it extract from all or just the last box drawn?

The extraction tool gives you the ability to select more than one area. You will need to select the area polygon box again to draw more than one selected area. The extraction file will not separate the object classes by the different selected areas.

How accurate and up to date is the ENC Direct data?

The NOAA ENC cells intended for navigation are updated for Notices to Mariners and other safety information. These updates are provided to navigational users of NOAA ENC cells as update patches. Periodically, NOAA ENC cells are released as complete new versions (called New Editions when referring to paper charts) that include all of the update patches.

ENC Direct to GIS data is updated every Saturday night. This includes all of the update patches or new editions available at that time.

Data contained in ENC Direct to GIS retains the accuracy of the original NOAA ENC data.