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COLREG

Rule 13: Overtaking

If you overtake another vessel, COLREG requires you to keep clear of her.

You · A
Decision 1 of 3

You are in A. B, faster, is coming up from astern with risk of collision. Who must keep out of the way?

How it applies

  1. WhenYou come up with another vessel from more than 22.5° abaft her beam: at night you would see only her sternlight, neither sidelight.
  2. Who gives wayThe overtaking vessel, whatever her type: power, sail or fishing. Rule 13 overrides the other Rules of Sections I and II.
    1. If in doubt whether you are overtaking, assume you are and act accordingly.
    2. A later change of bearing does not make you a crossing vessel: keep clear until finally past and clear.
  3. And the otherThe vessel being overtaken keeps her course and speed (Rule 17).
A vessel coming up from directly astern illustrates overtaking. Rule 13 covers approach from more than 22.5° abaft the beam. The overtaking vessel keeps out of the way until finally past and clear; no passing side is prescribed here.
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The full version

Practise Rule 13 in the Academy

Free: a preview of this unit with its key points. The whole unit is in the Exam Pass, once for 12 months.

What the Exam Pass adds

  • The interactive model: move the other vessel and see when it is overtaking and who keeps clear.
  • Four new sketched cases: on the quarter, at the limit, a sailing vessel and after passing.
  • The Rules 11 to 14 path, with your progress saved.
Preview Rule 13 in the Academy

Practise with the free test 40 questions with explained answers · no sign-up

Before you apply Rule 13

Rule 13 is for a vessel coming up on another from astern. In these cases another rule governs, or adds to it:

  • The other comes from less than 22.5° abaft your beam, or from aheadNot overtaking. Crossing with risk: Rule 15; meeting head-on: Rule 14.
  • A sailing vessel or a Rule 18 vessel overtakes youIt makes no difference: the overtaking vessel always keeps clear. Rule 18 starts "except where Rules 9, 10 and 13 otherwise require".
  • In a narrow channelIf the vessel being overtaken must act to let you pass, ask with the Rule 34(c) signals and she answers (Rule 9(e)). Rule 13 still applies.
  • Restricted visibility and not in sightRule 19 applies: there is no overtaking or stand-on vessel; each avoids a close-quarters situation.

Frequent mistakes

  • Wrong: "If I see only the sternlight, I am crossing."

    Right: That position fits an overtaking vessel: she is coming from more than 22.5° abaft the beam.

  • Wrong: "If the bearing changes, I become a crossing vessel."

    Right: A subsequent alteration does not change that status or remove your duty to keep clear.

  • Wrong: "If I am unsure, I act as though I am crossing."

    Right: When in doubt, assume you are overtaking and act accordingly.

More detail for the exam

The rule in plain words

What duty comes first?
Notwithstanding Part B, Sections I and II, an overtaking vessel shall keep out of the way of the vessel being overtaken.
When are you overtaking?
When coming up from more than 22.5° abaft her beam; at night you would see only the sternlight, not her sidelights.
What if you are unsure?
If in doubt whether you are overtaking another vessel, assume that this is the case and act accordingly.
Does a later bearing change help?
No: it does not make you a crossing vessel or relieve your duty to keep clear until finally past and clear.

Exam keys

  1. "Notwithstanding" at 13(a): the overtaking vessel keeps clear despite Part B Sections I and II.
  2. "More than 22.5° abaft": exactly 22.5° does not meet the literal threshold.
  3. A later bearing alteration does not create a crossing vessel; look for "until finally past and clear".

How to read it

The test is the geometry described: the bearing and the lights you would see at night, not a passing impression.

Read "until" as a real limit: the duty continues until you are finally past and clear.

Key points

  • Part B I–II do not change the overtaking vessel's duty.
  • More than 22.5° abaft the beam → overtaking.
  • Doubt → assume overtaking and act accordingly.
  • Later bearing ≠ crossing; wait until finally past and clear.

This rule's practice test is free in full, with no sign-up. The 10-question free limit applies to quizzes and mock exams.

Official text

IMO COLREG 1972 U.S. Coast Guard — International Navigation Rules (2024)

Full wording of the rule, reproduced from the official source below.

(a) Notwithstanding anything contained in the Rules of Part B, Sections I and II, any vessel overtaking any other shall keep out of the way of the vessel being overtaken. (b) A vessel shall be deemed to be overtaking when coming up with another vessel from a direction more than 22.5° abaft her beam, that is, in such a position with reference to the vessel she is overtaking, that at night she would be able to see only the sternlight of that vessel but neither of her sidelights. (c) When a vessel is in any doubt as to whether she is overtaking another, she shall assume that this is the case and act accordingly. (d) Any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel within the meaning of these Rules or relieve her of the duty of keeping clear of the overtaken vessel until she is finally past and clear.
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Reviewed by Ramon Curto, Nautical teacher at IECNPC · Last reviewed:

Frequently asked questions about COLREG Rule 13

Which vessel must keep out of the way when overtaking?

The overtaking vessel. Any vessel overtaking any other shall keep out of the way of the vessel being overtaken, notwithstanding anything contained in the Rules of Part B, Sections I and II (Rule 13(a)).

When is a vessel deemed to be overtaking under COLREG Rule 13?

When coming up with another vessel from a direction more than 22.5 degrees abaft her beam — a position from which, at night, she would see only the sternlight of that vessel but neither of her sidelights (Rule 13(b)).

What should you do if you are in doubt whether you are overtaking?

Assume that you are. Rule 13(c) requires a vessel in any doubt as to whether she is overtaking another to assume that this is the case and act accordingly.

Can an overtaking vessel become a crossing vessel as the bearing changes?

No. Any subsequent alteration of the bearing between the two vessels shall not make the overtaking vessel a crossing vessel, nor relieve her of the duty of keeping clear of the overtaken vessel until she is finally past and clear (Rule 13(d)).