Maryland's answer is short and unusually clean: one line, drawn in Virginia, makes the entire Maryland Chesapeake inland water. 33 CFR 80.510 runs Cape Charles Light to Cape Henry Light, and everything shoreward of it — Annapolis, the Solomons, the whole bay and its rivers — is Inland Rules water under 80.01(b). The state's only other line is 80.505(b) across Ocean City Inlet, 225° true from Ocean City Inlet Light 6 to the submerged south breakwater; clear that and an Ocean City boat is on the International Rules. So a Maryland candidate's rulebook depends on which side of the Delmarva the work is, and a service record that says only "Maryland" does not answer the question.
No Part 80 section is titled for Maryland. Ocean City Inlet is drawn at 33 CFR 80.505(b) inside a section headed Cape Henlopen, DE to Cape Charles, VA, and the whole Maryland Chesapeake lies shoreward of the single line at 80.510, Cape Charles Light to Cape Henry Light.
COLREGS Demarcation Lines covering Maryland — 33 CFR Part 80
- 33 CFR 80.505Cape Henlopen, DE to Cape Charles, VAline drawn — Inland water inside
- 33 CFR 80.510Chesapeake Bay Entrance, VAline drawn — Inland water inside
This decides which rulebook you steer by, not where your credential may operate: the route limit is the 46 CFR Part 7 Boundary Line, and the two lines are not drawn in the same place. How the two lines differ · International Rules · Inland Rules
33 CFR Part 80 and the Part 83 definitions above read from eCFR on 12 Aug 2026. Any specific water is a determination for the cognizant Coast Guard Officer in Charge, Marine Inspection.