There are 7 major vessel definitions:

1. Vessel = anything that can transport over the water and includes non-displacement craft and seaplanes.
2. Power-driven vessel = anything driven by machinery.
3. Sailing Vessel = any vessel driven by sails.
4. A vessel engaged in fishing = any vessel with Nets, Lines, Trawls, or other apparatus THAT RESTRICTS MANEUVERABILITY. If maneuverability is not restricted then the vessel isn’t treated as a ‘vessel engaged in fishing.
5. Seaplane = any aircraft designed to maneuver on the water.
6. Vessel not under command = a vessel that through exceptional circumstances is unable to maneuver required by these rules and is unable to keep clear of other vessels.
7. Vessel restricted in her ability to maneuver = a vessel that by the nature of her work can not easily keep clear of other vessels
   • Examples inlude:
     • A vessel engaged in laying, servicing or picking up a navigation mark, submarine cable or pipeline.
     • A vessel engaged in dredging, surveying or underwater operations.
     • A vessel engaged in replenishment or transferring persons, provisions or cargo while underway.
     • A vessel engage in the launching or recovery of aircraft.
     • A vessel engaged in mine clearance operations.
     • A vessel engaged in a towing operation such as severely restricts the towing vessel and her tow in their ability to deviate from their course.
8. Vessel constrained by her draft = power driven vessel which, because of her draft in relation to the available depth and width of navigable water is severely restricted in her ability to deviate from the course she is following.

Underway means a vessel is not:

1. Anchored
2. Connected to shore
3. Aground