Pecking order of vessels. There is a basic order, in the navigation rules, that governs who stays out of the way of whom. Essentially, the hardest to maneuver vessels are stand-on while the easiest to maneuver vessels are give-way. In the following list vessels further down give-way to vessels higher up.

· Not Under Command (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).
· Restricted in ability to maneuver (Shall include but not be limited to:
1. A vessel engaged in laying, servicing, or picking up a navigational mark, submarine cable or pipeline;
2. A vessel engaged in dredging, surveying or underwater operations;
3. A vessel engaged in replenishment or transferring persons, provisions or cargo while underway;
4. A vessel engaged in the launching or recovery of aircraft;
5. A vessel engaged in mine clearance operations;
6. 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.)

· Constrained by draft. This only applies to the International rules. (A 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).
· Fishing. These are commercial fishing vessels. (Any vessel fishing with nets, lines, trawls, or other fishing apparatus which restrict maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict maneuverability).
· Sail (any vessel under sail provided that propelling machinery, if fitted, is not being used)
· Power (any vessel propelled by machinery).
· Seaplane (Includes any aircraft designed to maneuver on the water).

Stand-on and give-way vessels. The give-way vessel stays out of the way of the stand-on vessel. This does not relieve the stand-on vessel of responsibilities. She is called the stand-on vessel because she must stand-on her course and speed. By doing so, she gives the give-way vessel a way to assess the situation as it develops. What if the give-way vessel does not get out of the way? In that situation the stand-on vessel will have to alter her course and/or speed to avoid danger.

The more maneuverable a vessel is the more likely it is to be the give-way vessel in a close quarters situation. This is why the powerboat is give-way to a sailboat; why a boat that is moving is give-way to a vessel stopped; and why they all give way to a large ship in a narrow channel.

One note on powerboats and sailboats. A sailboat is a boat that is being propelled by sail alone, if its engine is on and engaged it is considered to be a powerboat even with its sails up.

Responsibilities Between Vessels
(a) A power-driven vessel underway shall keep out of the way of:

    1. a vessel not under command;
    2. a vessel restricted in her ability to maneuver;
    3. a vessel engaged in fishing;
    4.  a sailing vessel.

(b) A sailing vessel underway shall keep out of the way of:

1. a vessel not under command;
2. a vessel restricted in her ability to maneuver;
3. a vessel engaged in fishing.

(c) A vessel engaged in fishing when underway shall, so far as possible, keep out of the way of:

1. a vessel not under command;
2. a vessel restricted in her ability to maneuver.

(d) 1. Any vessel other than a vessel not under command or a vessel restricted in her ability to maneuver shall, if the circumstances of the case admit, avoid impeding the safe passage of a vessel constrained by her draft, exhibiting the signals in Rule 28.

2. A vessel constrained by her draft shall navigate with particular caution having full regard to her special condition.
(e | d) A seaplane on the water shall, in general, keep well clear of all vessels and avoid impeding their navigation. In circumstances, however, where risk of collision exists, she shall comply with the Rules of this Part.

(f) 1. A WIG craft shall, when taking off, landing and in flight near the surface, keep well clear of all other vessels and avoid impeding their navigation;

2. a WIG craft operating on the water surface shall comply with the Rules of this Part as a power-driven vessel.
Sirena Azul-AJ Baxter photo

General Definitions
(a) The word “vessel” includes every description of watercraft, 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 restrict maneuverability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict maneuverability.

(e) The term “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” shall include but not be limited to:
1. A vessel engaged in laying, servicing, or picking up a navigational mark, submarine cable or pipeline;
2. A vessel engaged in dredging, surveying or underwater operations;
3. A vessel engaged in replenishment or transferring persons, provisions or cargo while underway;
4. A vessel engaged in the launching or recovery of aircraft;
5. A vessel engaged in mine clearance operations;
6. 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.

(h) The term “vessel constrained by her draft” means a 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.
(i | h) The word “underway” means that a vessel is not at anchor, or made fast to the shore, or aground.
(j | i) The words “length” and “breadth” of a vessel mean her length overall and greatest breadth.
(k | j) Vessels shall be deemed to be in sight of one another only when one can be observed visually from the other.
(l | k) 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.

(l) “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;
(m) “Great Lakes” means the Great Lakes and their connecting tributary waters including the Calumet River as far as the Thomas J. O’Brien Lock and Controlling Waters (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;

(n) “Secretary” means the Secretary of the department in which the Coast Guard is operating;

(o) “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;

(p) “Inland Rules” or “Rules” mean the 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; and

(q) “International Regulations” means the International Regulations for Preventing Collisions as Sea, 1972, including annexes currently in force for the United States.

Sources: http://www.uscg.mil/directives/cim/16000-16999/cim_16672_2d.pdf
http://www.amsea.org/pdf/rules_of_road_quick_reference.pdf