IALACOLREG

COLREG Rules — International Regulations for Preventing Collisions at Sea

Full rule-by-rule reference of COLREG 1972 (as amended), organized by Parts A–E. Plain-English explanations, common mistakes, exam traps, and FAQ for every rule.

A

Part A — General

3
B

Part B — Steering & Sailing Rules

16

Section III.Conduct in restricted visibility

C

Part C — Lights & Shapes

12
D

Part D — Sound & Light Signals

6
E

Part E — Exemptions

1

What are the COLREGs?

The COLREGs — formally the Convention on the International Regulations for Preventing Collisions at Sea, 1972 — are the worldwide ruleset every vessel must follow whenever it is on a sea connected with the high seas. Drafted by the International Maritime Organization (IMO), they replaced the older 1960 rules and have been amended several times, most recently by IMO Resolutions A.910(22) and A.1085(28).

There are 38 numbered rules grouped into five Parts. Part A sets out who the rules apply to and key definitions. Part B is the business end of collision avoidance: who gives way, when and how, in clear weather and in restricted visibility. Part C governs the lights and shapes a vessel must display so others can identify her at night or by day. Part D covers the sound and light signals used to communicate intent. Part E lists exemptions for old vessels.

Whether you are sitting a PER, RYA Day Skipper, USCG OUPV or STCW II/1 exam, the COLREGs are the single biggest topic in the syllabus — and the one most candidates lose marks on. The pages below explain every rule in plain English, with the exact mistakes examiners look for and the 3D vessel-light diagrams the legal text never shows you.

COLREG structure at a glance

PartRulesWhat it covers
A — General1–3Application, responsibility, definitions
B — Steering & Sailing4–19Conduct in any visibility, in sight of one another, and in restricted visibility
C — Lights & Shapes20–31Navigation lights and day shapes by vessel type
D — Sound & Light Signals32–37Whistle, bell, gong and distress signals
E — Exemptions38Transitional exemptions for vessels in service before 1977

Most-studied COLREG topics

Frequently asked questions

What does COLREG stand for?
COLREG is shorthand for the Convention on the International Regulations for Preventing Collisions at Sea, 1972. You'll also see COLREGS (the rules themselves), IRPCS (the British abbreviation), RIPA (Spain), RIPAM (France) and KVR (Germany) — all refer to the same IMO text.
Are the COLREGs the same in every country?
The international rules are identical worldwide; coastal states may add LOCAL rules for inland waters (US Inland Rules, UK harbour by-laws, Spain's RGAGNB on inland waters). When inland and international rules differ, the inland rule applies inside the demarcation line.
Which COLREG rule causes the most exam mistakes?
Rule 19 (conduct in restricted visibility). Candidates routinely confuse it with Rules 11–18 (in sight of one another). In fog you cannot see the other vessel, so the give-way / stand-on framework does not apply — both vessels must take action as set out in Rule 19.
Do COLREGs apply to small boats and jet skis?
Yes. Rule 1 says they apply to all vessels on the high seas and on all waters connected with the high seas. A jet ski is a power-driven vessel and must comply with sidelights, sound signals and steering rules just like a tanker.
When were the COLREGs last updated?
The most recent IMO amendments entered into force in 2016 (Resolution A.1085(28)). They tightened wording around high-speed craft, partly-submerged towing operations and air-cushion vessels. The fundamentals (give-way, stand-on, lights) have been stable since 1977.