The hierarchy of USCG waters is Oceans -> Near Coastal -> Great Lakes, -> Inland. There are some exceptions for towing and Western Rivers.
What does this mean?
From 46 CFR 11
Oceans
Subject to provisions about Western Rivers, any license or MMC endorsement for service as master or mate on ocean waters qualifies the mariner to serve in the same grade on any waters, except towing vessels upon western rivers subject to the limitations of the endorsement.
Near Coastal
Subject to provisions about Western Rivers, any license or MMC endorsement issued for service as master or mate on near-coastal waters qualifies the mariner to serve in the same grade on Great Lakes and inland waters, except towing vessels upon western rivers subject to the limitations of the endorsement.
Great Lakes
Any officer endorsement issued for service on Great Lakes and inland waters self-propelled vessels, excluding towing vessels, is valid on all of the inland waters of the United States
Inland
Any officer endorsement issued for service on inland waters of self-propelled vessels, excluding towing vessels, is valid for the inland waters of the United States, excluding the Great Lakes.
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About the author
Nate Gilman is President and Co-Founder of MM-SEAS. He hawsepiped from the deck to a 3rd Mate Unlimited license with full STCW compliance over more than 15 years at sea, and is a veteran of the NOAA Commissioned Corps. He works directly with the National Maritime Center, USCG-approved training schools, and vessel operators on credentialing policy, and writes on sea service documentation, evaluation standards, and how mariners move up the license ladder.
