33 CFR § 83.03 - General definitions (Rule 3).
For the purpose of these Rules and Subchapter E, except where the context otherwise requires:
(a) The word vessel includes every description of water craft, including non-displacement craft, WIG craft and seaplanes, used or capable of being used as a means of transportation on water.
(b) The term power-driven vessel means any vessel propelled by machinery.
(c) The term sailing vessel means any vessel under sail provided that propelling machinery, if fitted, is not being used.
(d) The term vessel engaged in fishing means any vessel fishing with nets, lines, trawls, or other fishing apparatus which restricts maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict maneuverability.
(e) The word seaplane includes any aircraft designed to maneuver on the water.
(f) The term vessel not under command means a vessel which, through some exceptional circumstance, is unable to maneuver as required by these Rules and is therefore unable to keep out of the way of another vessel.
(g) The term vessel restricted in her ability to maneuver means a vessel which, from the nature of her work, is restricted in her ability to maneuver as required by these Rules and is therefore unable to keep out of the way of another vessel. The term vessels restricted in their ability to maneuver include, but are not limited to:
(i) A vessel engaged in laying, servicing, or picking up a navigation mark, submarine cable, or pipeline;
(ii) a vessel engaged in dredging, surveying, or underwater operations;
(iv) a vessel engaged in the launching or recovery of aircraft;
(v) a vessel engaged in mine clearance operations;
(i) The word underway means that a vessel is not at anchor, or made fast to the shore, or aground.
(k) Vessels shall be deemed to be in sight of one another only when one can be observed visually from the other.
(l) The term restricted visibility means any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms, or any other similar causes.
(m) The term Wing-In-Ground (WIG) craft means a multimodal craft which, in its main operational mode, flies in close proximity to the surface by utilizing surface-effect action.
(n) Western Rivers means the Mississippi River, its tributaries, South Pass, and Southwest Pass, to the navigational demarcation lines dividing the high seas from harbors, rivers, and other inland waters of the United States, and the Port Allen-Morgan City Alternate Route, and that part of the Atchafalaya River above its junction with the Port Allen-Morgan City Alternate Route including the Old River and the Red River.
(o) Great Lakes means the Great Lakes and their connecting and tributary waters including the Calumet River as far as the Thomas J. O'Brien Lock and Controlling Works (between mile 326 and 327), the Chicago River as far as the east side of the Ashland Avenue Bridge (between mile 321 and 322), and the Saint Lawrence River as far east as the lower exit of Saint Lambert Lock.
(p) Secretary means the Secretary of the Department in which the Coast Guard is operating.
(q) Inland Waters means the navigable waters of the United States shoreward of the navigational demarcation lines dividing the high seas from harbors, rivers, and other inland waters of the United States and the waters of the Great Lakes on the United States side of the International Boundary.
(r) Inland Rules or Rules means these Inland Navigational Rules and the annexes thereto, which govern the conduct of vessels and specify the lights, shapes, and sound signals that apply on inland waters.
(s) International Regulations means the International Regulations for Preventing Collisions at Sea, 1972, including annexes currently in force for the United States.