International Rules are specific rules for all vessels on the high seas and in connecting waters navigable by seagoing vessels. The Inland Rules apply to all vessels upon the inland waters of the United States and to vessels of the United States on the Canadian waters of the Great Lakes to the extent that there is no conflict with Canadian law. The International Rules were formalized at the convention on the International Regulations for Preventing Collisions at Sea, 1972. These rules are commonly called 72 COLREGS.
Inland Rules vary from International Rules primarily because of the addition of certain extra precautions. In our discussion of basic rules, each rule stated is the same for both international and inland waters unless a distinction was pointed out. When the term power-driven vessel is mentioned, for example, it means in both International and Inland, any vessel propelled by machinery as distinguished from a sailing vessel.
For the purpose of these rules, except where the context otherwise requires, the following definitions apply:
The term Inland waters means the navigable waters of the United States shoreward of the demarcation lines which divide the high seas from harbors, rivers, and other bodies of waters of the United States, and the waters of the Great Lakes of the United States’ side of the international boundary.
Demarcation lines are the lines that designate those waters upon which mariners must comply with the 72 COLREGS and those waters upon which mariners must comply with the Inland Navigation Rules. Nautical charts typically include a demarcation line that shows when the Navigation Rules transition from inland to international, so that boaters can be aware of changing standards of navigation. In general, these demarcation lines follow the coastline and cross-inlets and bays. On the seaward side of the demarcation lines, international rules apply.
With regards to the Rules of the Road the term Underway means that a vessel is not at anchor, made fast to shore, or aground.
The word vessel includes every description of watercraft, including non-displacement craft and seaplanes, used or capable of being used as a means of transportation on water.
The term power-driven vessel means any vessel propelled by machinery.
The term sailing vessel means any vessel under sail provided that propelling machinery, if fitted, is not being used.
The term vessel engaged in fishing means any vessel fishing with nets, lines, trawls, or other fishing apparatus that restrict maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus that do not restrict maneuverability.
The word seaplane includes any aircraft designed to maneuver on the water.
Restricted visibility means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, or any other similar causes.