Every officer of the watch uses the Collision Regulations. But do you really know how the book is laid out? This lesson gives you the map, so you can find the right rule in seconds.
What is COLREG
COLREG is the Convention on the International Regulations for Preventing Collisions at Sea. The IMO adopted it in 1972 and it entered into force in 1977. It contains 38 rules and four annexes.
The five parts at a glance
| Part | Title | Rules | On watch, it answers |
|---|---|---|---|
| A | General | 1–3 | The ground rules |
| B | Steering and Sailing Rules | 4–19 | What must I do? |
| C | Lights and Shapes | 20–31 | What do I see? |
| D | Sound and Light Signals | 32–37 | What do I hear and sound? |
| E | Exemptions | 38 | Transitional provisions |
Part A — General (Rules 1–3)
Rule 1: application. Rule 2: responsibility. Rule 3: definitions.
Remember Rule 2: the rules never replace good seamanship.
Part B — Steering and Sailing Rules (Rules 4–19)
The biggest part, with 16 rules. It tells you what to do.
- Section I, Rules 4–10 — any condition of visibility: look-out, safe speed, risk of collision, action to avoid collision, narrow channels, traffic separation schemes.
- Section II, Rules 11–18 — vessels in sight of one another: sailing vessels, overtaking, head-on, crossing, give-way and stand-on duties, responsibilities between vessels.
- Section III, Rule 19 — conduct of vessels in restricted visibility.
Part C — Lights and Shapes (Rules 20–31)
What you see. First the definitions and visibility of lights; then power-driven vessels, towing and pushing, and sailing vessels; then the special cases: fishing, not under command, restricted in ability to manoeuvre, constrained by draught, pilot vessels, anchored vessels and seaplanes. Exact positions and technical details are in Annex I.
Part D — Sound and Light Signals (Rules 32–37)
What you hear and sound. Rules 32 and 33 define the signals and the equipment to carry. Rule 34 manoeuvring signals:
- One short blast — altering course to starboard
- Two short blasts — altering course to port
- Three short blasts — operating astern propulsion
- Five or more short blasts — doubt or danger
Rule 35 gives the signals for restricted visibility. Rules 36 and 37 cover signals to attract attention and distress signals — listed in Annex IV.
Part E — Exemptions (Rule 38) and the Annexes
Part E has one rule. It gave older ships time to comply with new requirements, so today it is mostly of historical interest. After the rules come four annexes:
- 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 — Distress signals
How to remember it
Good Sailors Learn Signals Early — General, Steering and sailing, Lights, Signals, Exemptions.
On watch, ask yourself: What must I do? Open Part B. What do I see? Part C. What do I hear? Part D.
This lesson is for training purposes. Always refer to the current official IMO text of COLREG and your company procedures.