Atlantic Cadastral Data

The Geospatial Services Division performs mathematical offshore boundary location computations and prepares Official Protraction Diagrams (OPDs), and Supplemental Official OCS Block Diagrams (SOBDs) depicting OCS Block information, the Submerged Lands Act Boundary (aka - State Seaward Boundary), Limit of "8(g) Zone", the Continental Shelf Boundary (CSB) which marks the limit of U.S. jurisdiction for offshore mineral development, and corresponding area measurements. The analytical procedures employed and the computer programs utilized to perform various offshore boundary geometric computations are described in OCS Report MMS 99-0006.

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OPD Images

A standard Official Protraction Diagrams (OPD) is 1 degree in latitude by 2 degrees in longitude (at lower latitudes: 0 - 48 degrees). At higher latitudes (48 - 75 degrees) such as Alaska and northern Washington, OPDs are 3 degrees wide. OPD limits usually approximate the standard 1:250,000 scale U.S. Geological Survey topographic map series. The OPDs are numbered using the United Nations International Map of the World Numbering System. OPD names usually coincide with standard topographic sheet names when diagrams include land areas. OPD sheet names relate to land features, or to hydrographic features contained within the limits of the diagram. Shoreline planimetric detail is shown when it falls within the limits of a diagram. Older OPDs were prepared on mylar with manual cartographic methods and then scanned into Adobe .pdf files. Newer OPDs were prepared electronically and converted to Adobe .pdf files. 

NOTE: Atlantic OPDs that show the Submerged Lands Act and Section 8(g) Zone boundaries do not reflect post-2010 shoreline changes.

SOBD Images

A Supplemental Official OCS Block Diagram (SOBD) is prepared for each block intersected by an offshore boundary (Submerged Lands Act Boundary, Limit of "8(g) Zone", National Marine Sanctuaries, etc.). Note that not all OPDs contain such boundaries; therefore not all OPDs have SOBDs associated with them. The zip files offered here contains only current NAD 83 SOBDS. The historic (outdated) SOBDs can be obtained by contacting the Geospatial Services Division. All future activities will be based on the most current SOBDs. 

NOTE: Atlantic SOBDs do not reflect post-2010 shoreline changes.

Offshore Marine Cadastre (OMC) Navigator

The Offshore Marine Cadastre (OMC) Navigator is a national viewer showing Protractions, Blocks, Aliquots, and Boundaries covering the Outer Continental Shelf (OCS). These are units of area measurement that officially describe the OCS and demarcate areas that could be leased for energy in accordance with 30 CFR 550.400, 30 CFR 585.205, and 30 CFR 581.15. The main purpose of the viewer is to provide PDF links to BOEM’s Official Mapping Products known as Official Protraction Diagram Index Maps, Official Protraction Diagrams (OPDs), Official Protraction Aliquots Diagrams (OPADs), and Supplemental Official Block Diagrams (SOBDs).

GIS Files 

The various boundaries can be viewed in BOEM’s GeoSEAS ArcGIS Online (AGOL) as services. They are also offered as ESRI ArcGIS shapefiles. Shapefiles can be viewed with ArcGIS or a variety of other GIS systems. The shapefiles have been zipped using WinZip.

Note: The precise coordinates of a GIS file can be altered slightly by various GIS functions. For that reason, these GIS files are not an Official Record for BOEM offshore boundaries. Only the coordinates shown on Official OPDs, and SOBDs constitute an Official Record for offshore coordinate values.