THE HIGH-RESOLUTION BATHYMETRIC OVERLAY CONCEPT IS NOT A NEW ONE
- The Port of Hamburg is producing a bathymetric ENC (bENC) for use with its port ENC.
- The U.S. Army Corps of Engineers is using the IENC specification to produce overlays containing soundings and contours from the channel condition surveys for the Mississippi River in Southwest Pass. The USACE overlays are updated weekly. They must be used with the appropriate NOAA ENC.
- USACE Overlays for the Southwest Pass can be found at
- If needed, the xml catalogue for IENC overlays can be found at
- The Canadian Hydrographic Service is producing S-102 bathymetric grids for the St. Lawrence Seaway.
Mariners and pilots increasingly need high-resolution bathymetry on chart displays. Currently, however, NOAA charts (paper, raster, and ENC) only supply a controlling depth from the latest hydrographic survey.
A NOAA demonstration project, now in development, will produce high-resolution bathymetric overlays for the Port of Los Angles and Port of Long Beach, using the Inland ENC (IENC) specification for soundings and contours. The project will also create an overlay using S-102 to provide a bathymetric attributed grid, including depth profiles of the port’s channels and approaches.
IENC Product Specification 2.4 – bathymetric Inland ENCs
Developed by the Inland ENC Harmonization Group, this IENC Specification Version 2.4 is a profile of the International Hydrographic Organization S-57 Electronic Navigational Chart Product Specification, which has been modified to allow creation of bathymetric Inland ENCs. Bathymetric Inland ENCs contain Depth Area features that have been produced at a higher density than traditional depth areas that are contained within the ENC.
Coast Survey has produced a set of 50 bIENC overlay files for Long Beach harbor. The data in these overlays has been derived from the most current hydrographic surveys available.
You can download these bIENC cells in the following zip file: LA-LB_bIENC.zip
IENC Product Specification 2.2
Developed by the Inland ENC Harmonization Group, this IENC specification is a profile of the International Hydrographic Organization S-57 Electronic Navigational Chart Product Specification, which has been modified to allow creation of overlay files.
IENC Overlay Files for the Gulf of Mexico Oil and Gas Lease Blocks
Coast Survey is providing a set of 6 IENC overlay files for the Gulf of Mexico Oil and Gas Lease Blocks. These lease blocks were created from the BOEM Gulf of Mexico geographic mapping data. These overlays are for situational awareness and do not constitute the legal boundaries of the official lease blocks. The legal boundaries can be found by reviewing the appropriate Leasing Map or Official Protraction Diagram found here: http://www.boem.gov/Official-Protraction-Diagrams
You can download these IENC cells in the following zip file: BOEMOilGasBlockTileIENC22final.zip
IENC Overlay Files for San Pedro Bay, CA
Coast Survey is providing a set of 68 IENC overlay files for San Pedro Bay which represents conditions for the Ports of Los Angeles and Long Beach. The data in these overlays has been derived from the most current hydrographic surveys available.
You can download these IENC cells in the following zip file: SanPedroBayHighResolutionOverlays.zip
IHO S-102 Specification
The International Hydrographic Organization publishes the S-102 standard for high-resolution bathymetric datasets for eventual use with the next generation ENC product specification.
Coast Survey is producing prototype S-102 datasets to test the functionality of S-102 and to provide datasets that contain richer bathymetric content.
A NOTE ON DATA PORTRAYAL
Since this data is not intended for use in an electronic chart display and information system (ECDIS) at this time, there are no specific portrayal rules. The features that will be part of the IENC overlay are the same features that are found in the IHO S-57 specification, so it is possible to use the IHO S-52 standard for the display. However, since the intent is to provide the mariner with richer data content, the S-52 restrictions on providing the ability to color code the depth contours and soundings based on user input do not apply.
Page last edited: February 17, 2017