Define a 'vessel restricted in her ability to manoeuvre' and give three examples.

Rule 3(g): a vessel which from the nature of her work is restricted in her ability to manoeuvre as required by the Rules and is therefore unable to keep out of the way of another vessel. Examples: laying/servicing a navigation mark, cable or pipeline; dredging, surveying or underwater operations; replenishment or transferring persons/stores under way; launching/recovering aircraft; mine clearance; a towing operation severely restricting the tow's ability to deviate. Trap: a deep-draught ship is NOT RAM — she is a CBD (Rule 3(h)).

What is the difference between 'vessel not under command' and 'restricted in ability to manoeuvre'?

NUC (Rule 3(f)): through some exceptional circumstance a vessel is unable to manoeuvre as required and so cannot keep out of the way — e.g. engine or steering failure. RAM (Rule 3(g)): the vessel cannot manoeuvre because of the nature of her work. Lead: NUC is a breakdown she didn't choose; RAM is the job she is doing — same two-red/ball-diamond-ball family of shapes but different day shapes (two balls vs ball-diamond-ball).

When are two vessels 'in sight of one another' — and why does it matter?

Rule 3(k): only when one can be observed visually from the other. It matters because the give-way / stand-on Rules 11–18 apply only when vessels are in sight of one another; if you detect her by radar alone in restricted visibility, Rule 19 governs and there is no stand-on vessel. Trap: a radar contact is not 'in sight' — don't apply the crossing rule to it.

A ship has stopped her engine and is drifting in open water. Is she 'under way'?

Yes. Rule 3(i): 'under way' means not at anchor, not made fast to the shore, and not aground. A vessel stopped and drifting with her engines off is still under way — she is simply not making way through the water. Trap: 'under way' ≠ 'making way'. She shows steaming lights (not anchor lights) and, in fog, the two-prolonged-blast signal for a power-driven vessel under way but stopped.

Distinguish 'making way' from 'under way'.

'Under way' (Rule 3(i)) is a legal state — not anchored, moored or aground. 'Making way' means actually moving through the water under her own power or momentum. A vessel can be under way but not making way (stopped/drifting). The distinction drives the fog signals: one prolonged (making way) vs two prolonged (under way, stopped). Tip: count the prolonged blasts in fog — one = making way, two = under way but stopped.

Part A · General

COLREGS Rule 3 — General Definitions

Q: Define 'restricted visibility'.

Rule 3(l): any condition in which visibility is restricted by fog, mist, falling snow, heavy rainstorms, sandstorms or any other similar causes. Lead: it's the *cause* reducing visibility, not a fixed range in miles.

Q: Is a seaplane on the water a 'vessel'? Is a WIG craft?

Yes to both. Rule 3(a): 'vessel' includes every description of watercraft, including non-displacement craft, WIG craft and seaplanes, used or capable of being used as a means of transport on water. Lead: if it can carry over water, it's a vessel and the Rules bind it.

For the purpose of these Rules, 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 restrict manoeuvrability, but does not include a vessel fishing with trolling lines or other fishing apparatus which do not restrict manoeuvrability.

(e) The word 'seaplane' includes any aircraft designed to manoeuvre on the water.

(f) The term 'vessel not under command' means a vessel which through some exceptional circumstance is unable to manoeuvre 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 manoeuvre' means a vessel which from the nature of her work is restricted in her ability to manoeuvre as required by these Rules and therefore is unable to keep out of the way of another vessel. The term 'vessels restricted in their ability to manoeuvre' shall include but not be 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;

(iii) a vessel engaged in replenishment or transferring persons, provisions or cargo while underway;

(iv) a vessel engaged in the launching or recovery of aircraft;

(v) a vessel engaged in mine clearance operations;

(vi) 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 draught' means a power-driven vessel which because of her draught 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) The word 'underway' means that a vessel is not at anchor, or made fast to the shore, or aground.

(j) The words 'length' and 'breadth' of a vessel mean her length overall and greatest breadth.

(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.

COLREGS Rule 3 — General Definitions

All COLREGS Rules and Annexes

Part A · General

Part B · Steering and sailing rules

Part C · Lights and shapes

Part D · Sound and light signals

Part E · Exemptions

Part F · Verification of compliance

Annex I · Positioning and technical details of lights and shapes

Annex II · Additional signals for fishing vessels fishing in close proximity

Annex III · Technical details of sound signal appliances

Annex IV

Also free for seafarers

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