Rule Library

Rule 1

Application

Defines exactly where COLREG applies and how local/special rules fit without breaking international consistency.

Rule 2

Responsibility

COLREG never replaces prudent seamanship: legal compliance and professional judgement must work together.

Rule 3

General definitions

Defines the vocabulary that decides which COLREG obligations apply in each encounter.

Rule 4

Section I application

Section I is always active, regardless of visibility.

Rule 5

Look-out

Keep an effective look-out continuously, using human senses and all available tools.

Rule 6

Safe speed

Safe speed is the speed that still lets you avoid collision effectively and stop in time.

Rule 7

Risk of collision

Use every available method to detect collision risk early; if unsure, treat it as risk.

Rule 8

Action to avoid collision

Avoiding action must be early, clear, substantial and monitored until finally past and clear.

Rule 9

Narrow channels

In narrow channels, keep disciplined starboard-side track and never impede vessels constrained to the channel.

Rule 10

Traffic separation schemes

In TSS, follow lane logic strictly and avoid impeding organized traffic flow.

Rule 11

Section II application

Section II applies only when vessels are visually in sight of each other.

Rule 12

Sailing vessels

Between sailing vessels: port tack gives way; windward gives way to leeward.

Rule 13

Overtaking

Overtaking duty is strict: the overtaking vessel keeps clear until finally past and clear.

Rule 14

Head-on

Head-on between power-driven vessels: both alter to starboard and pass port-to-port.

Rule 15

Crossing

In crossing, if the other vessel is on your starboard side, you are the give-way vessel.

Rule 16

Action by give-way vessel

The give-way vessel must act first, early and decisively.

Rule 17

Action by stand-on vessel

Stand-on vessel maintains course/speed initially, but must intervene if safety requires it.

Rule 18

Responsibilities between vessels

Establishes the encounter hierarchy between vessel categories, with important exceptions.

Rule 19

Conduct in restricted visibility

In restricted visibility without visual contact, navigate defensively with radar discipline and immediate readiness.

Rule 20

Application of lights and shapes

Sets when lights and shapes must be shown and forbids confusing extra lights.

Rule 21

Definitions

Defines each navigation light by color, arc and position so aspect can be interpreted correctly.

Rule 22

Visibility of lights

Specifies minimum visible range for each light type by vessel length category.

Rule 23

Power-driven vessels underway

Power-driven vessels underway show a standard light set, with clear size and craft-type variations.

Rule 24

Towing and pushing

Towing and pushing operations require additional lights/shapes to communicate tow geometry and hazard.

Rule 25

Sailing vessels underway and vessels under oars

Sailing vessels have their own light logic; machinery use changes status and obligations.

Rule 26

Fishing vessels

Fishing lights/shapes depend on method (trawling vs other fishing) and gear extension.

Rule 27

Not under command or restricted in ability to manoeuvre

NUC and RAM signals announce reduced manoeuvrability and require immediate recognition by others.

Rule 28

Vessel constrained by draught

A CBD vessel may display optional special signals to show severe draught constraints.

Rule 29

Pilot vessels

Pilot vessels use a distinctive white-over-red identity, with extra lights according to underway/anchor status.

Rule 30

Anchored vessels and vessels aground

Anchored and aground vessels must display unmistakable status signals, with limited small-vessel exemptions.

Rule 31

Seaplanes

Seaplanes and WIG craft must show the closest practicable equivalent to prescribed lights/shapes.

Rule 32

Definitions

Defines whistle terminology and timing that gives legal meaning to sound signals.

Rule 33

Equipment for sound signals

Required sound equipment scales with vessel length, with audibility and manual-use requirements.

Rule 34

Maneuvering and warning signals

Whistle/light manoeuvring signals communicate intentions clearly when vessels are in sight.

Rule 35

Sound signals in restricted visibility

In restricted visibility, each vessel status has a specific fog-signal pattern and interval.

Rule 36

Signals to attract attention

You may attract attention, but never by creating confusion with regulated signals or AtoN.

Rule 37

Distress signals

Distress and request for assistance must use Annex IV recognized signals.

Rule 38

Exemptions

Provides transitional exemptions for older vessels built under earlier regulations, with strict limits.

IALA

IALA lateral marks (Region A & B)

Lateral marks indicate the port and starboard sides of a channel relative to the conventional direction of buoyage, with colours reversed between IALA Region A and Region B.

IALA

Cardinal marks (N, E, S, W)

Cardinal marks indicate the compass quadrant where safe navigable water lies relative to a hazard, using black/yellow colour bands and cone topmarks whose arrangement encodes the compass direction.

IALA

Isolated danger marks

An isolated danger mark is placed on or moored above a hazard with navigable water all around it. Give wide clearance—do not pass between the mark and the danger.

IALA

Safe water marks

Safe water marks indicate navigable water all around — there is no danger. They are used as landfall marks, mid-channel marks, or fairway centreline buoys.

IALA

Special marks

Special marks are yellow and denote areas or features referred to in nautical publications — they indicate a special purpose, not a navigational hazard.

IALA

Emergency wreck marking buoy

Emergency wreck marking buoys are deployed rapidly over new, uncharted wrecks to warn traffic. They are temporary and use a unique blue-yellow colour scheme with alternating flashing lights.