IALACOLREG
1

Application

COLREG applies to all vessels on the high seas and in connected waters navigable by seagoing vessels, subject to closely conforming local special rules and IMO-adopted traffic separation schemes.

Rule 1 establishes the scope of the International Regulations for Preventing Collisions at Sea (COLREG). They apply to all vessels upon the high seas and in all waters connected therewith that are navigable by seagoing vessels.

a
Appropriate authorities may make special local rules for roadsteads, harbours, rivers, lakes and inland waterways connected with the high seas. Those rules must conform as closely as possible to COLREG.
b
Governments may also make special provisions for additional lights, shapes or whistle signals for ships of war, vessels under convoy and fishing vessels engaged in fishing as a fleet.
c
Traffic separation schemes may be adopted by the IMO for the purposes of these Rules. A vessel still has to comply with the rest of COLREG unless a specific routing provision applies.

STCW Bridge Watch Lens

1

Decide applicability before manoeuvring: Rules 4-10 apply in any visibility, Rules 11-18 only when vessels are in sight, and Rule 19 governs radar-only encounters in restricted visibility.

2

Build the traffic picture with sight, hearing, radar/ARPA and chart context. Do not let AIS or one isolated bearing replace systematic observation.

3

After manoeuvring, keep monitoring bearing, range, CPA/TCPA and passing distance until the other vessel is finally past and clear.

Exam Focus

1

Start every scenario by classifying the encounter: overtaking, head-on, crossing, narrow channel, traffic separation, or restricted visibility.

2

If two rules seem to conflict, check the order carefully: overtaking duties still apply, and Rule 2 still requires ordinary seamanship.

Key Takeaways

1

COLREG is not limited to merchant ships or blue-water passages

2

Local harbour and inland-water rules may supplement COLREG but should stay as close as possible to it

3

Special government light and signal rules exist for warships, convoys and fleet fishing

4

Traffic separation schemes used under COLREG are adopted through the IMO framework

Common Mistakes

Assuming COLREG only applies outside territorial waters

Treating local port rules as if they cancel the collision rules altogether

Test Your Knowledge

Test your knowledge and prove your mastery.