Reference

Regulations

The International Regulations for Preventing Collisions at Sea, organised so you can find the rule you need in seconds.

IRPCS / COLREGs

41 rules and 4 annexes, fully searchable and cross-linked.

Common questions

Who gives way to whom?

The order of priority is: not under command, restricted in ability to manoeuvre, fishing, sailing, then power-driven.

Rule 18

Two sailing boats are converging

Port tack gives way to starboard tack. On the same tack, the windward boat keeps clear of the leeward boat.

Rule 12

Two power-driven vessels crossing

The vessel with the other on her starboard side gives way, and avoids crossing ahead.

Rule 15Rule 16Rule 17

Meeting head-on

Both vessels alter course to starboard and pass port to port.

Rule 14

Overtaking

The overtaking vessel keeps out of the way until she is finally past and clear.

Rule 13Rule 9

What does five short blasts mean?

I do not understand your intentions, or I doubt you are taking enough action to avoid collision.

Rule 34

Navigating in fog

Safe speed, engines ready, proper radar use, and avoid altering to port for a vessel forward of the beam.

Rule 19Rule 35Rule 6

Who gives way

Rule 18 priority, most privileged first. Rules 9, 10 and 13 override this order.

  1. 1Vessel not under commandRule 3(f) · two all-round red lights
  2. 2Restricted in ability to manoeuvreRule 3(g) · red, white, red
  3. 3Constrained by her draughtRule 28 · three all-round red lights
  4. 4Engaged in fishingRule 26 · green over white, or red over white
  5. 5Sailing vesselRule 25 · sidelights and sternlight
  6. 6Power-driven vesselRule 23 · masthead light, sidelights, sternlight
Read Rule 18

Sound signals

I am altering my course to starboard1 short · Rule 34
I am altering my course to port2 short · Rule 34
I am operating astern propulsion3 short · Rule 34
I do not understand your intentions / I doubt you are taking enough action5 or more short · Rule 34
I am approaching a blind bend or obstruction1 prolonged · Rule 34
I intend to overtake you on your starboard side2 prolonged + 1 short · Rule 34
I intend to overtake you on your port side2 prolonged + 2 short · Rule 34
Agreement to be overtaken in a narrow channelprolonged, short, prolonged, short · Rule 34
Power-driven vessel making way in restricted visibility1 prolonged every 2 min · Rule 35
Power-driven vessel underway but stopped2 prolonged every 2 min · Rule 35
Sailing, fishing, towing, not under command, restricted in ability to manoeuvre, or constrained by draught1 prolonged + 2 short every 2 min · Rule 35
Vessel being towed (last vessel of the tow, if manned)1 prolonged + 3 short every 2 min · Rule 35

A short blast is about one second. A prolonged blast is four to six seconds.

Browse by part

Part ARules 1–3

General

Application, responsibility and the definitions the rest of the rules rely on.

Part B · Section IRules 4–10

Conduct of vessels in any condition of visibility

Look-out, safe speed, risk of collision, narrow channels and traffic separation schemes.

Part B · Section IIRules 11–18

Conduct of vessels in sight of one another

Who gives way: sailing, overtaking, head-on, crossing and the pecking order between vessel types.

Part B · Section IIIRule 19

Conduct of vessels in restricted visibility

How to navigate in fog when you cannot see the other vessel.

Part CRules 20–31

Lights and shapes

What every vessel must show, by night and by day.

Part DRules 32–37

Sound and light signals

Manoeuvring signals, fog signals and distress signals.

Part ERule 38

Exemptions

Transitional exemptions for vessels built before the rules came into force.

Part FRules 39–41

Verification of compliance

Audit and verification obligations on flag states.