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Rule 9: Narrow Channels (COLREGS)

Last reviewed October 21, 2026

The short answer

Rule 9 says a vessel in a narrow channel or fairway keeps as near to the outer limit on her starboard side as is safe and practicable. Small vessels, sailing vessels, and fishing vessels must not impede vessels that can only navigate in the channel, and every vessel should avoid anchoring there.

The rule text

A vessel proceeding along the course of a narrow channel or fairway shall keep as near to the outer limit of the channel or fairway which lies on her starboard side as is safe and practicable.

International Rules, U.S. Coast Guard Navigation Rules and Regulations Handbook (NAVCEN, 2024 corrected edition), Rule 9

A vessel of less than 20 meters in length or a sailing vessel shall not impede the passage of a vessel which can safely navigate only within a narrow channel or fairway.

International Rules, U.S. Coast Guard Navigation Rules and Regulations Handbook (NAVCEN, 2024 corrected edition), Rule 9

What it means on the water

  • Keep to the starboard side of the channel (Rule 9(a)).
  • Under 20 meters or under sail: don't impede a vessel that can only navigate within the channel (9(b)). Fishing vessels: don't impede any other vessel in the channel (9(c)).
  • Don't cross if it impedes a vessel that can only navigate within the channel; she may sound the doubt signal of Rule 34(d) (9(d)).
  • Overtaking that needs the other vessel's cooperation uses the Rule 34(c) signals, and Rule 13 still applies (9(e)).
  • Nearing a bend or obstruction: particular alertness and caution, and the Rule 34(e) signal (9(f)). Avoid anchoring in a narrow channel (9(g)).

International vs Inland

Inland adds Rule 9(a)(ii): on the Great Lakes, Western Rivers, or waters specified by the Secretary, a power-driven vessel downbound with a following current has the right-of-way over an upbound vessel, proposes the manner and place of passage, and initiates the Rule 34(a)(i) signals, while the upbound vessel holds as necessary. Inland 9(e) applies between power-driven vessels and uses the Inland Rule 34(c) signals; International 9(e) applies when overtaking can take place only if the vessel to be overtaken acts, using International 34(c).

Common exam traps

  • Thinking a sailing vessel has priority in a narrow channel. Rule 9(b) says she must not impede.
  • Using Inland overtaking signals in International waters.
  • Forgetting Rule 9(e)(ii): the overtaking vessel still has her Rule 13 duty.

Try 3 questions on Rule 9

  1. In a narrow channel, which side do you keep to?

    1. Port
    2. Starboard
    3. Center
    4. Whichever is deeper
    Show answer

    B. Starboard Rule 9(a).

  2. A 15-meter sailboat in a narrow channel meets a large ship that can only navigate within it. What must the sailboat do?

    1. Stand on
    2. Not impede the ship
    3. Sound one prolonged blast
    4. Anchor
    Show answer

    B. Not impede the ship Rule 9(b).

  3. On the Western Rivers (Inland), who proposes the manner and place of passage?

    1. The upbound vessel
    2. The power-driven vessel downbound with a following current
    3. The larger vessel
    4. The vessel on the right
    Show answer

    B. The power-driven vessel downbound with a following current Inland Rule 9(a)(ii).

Frequently asked questions

Does a sailboat have right of way in a narrow channel?

No. Under Rule 9(b) a sailing vessel shall not impede a vessel that can safely navigate only within the channel.

Can I anchor in a narrow channel?

Rule 9(g) says any vessel shall, if the circumstances admit, avoid anchoring in a narrow channel.

What signal do I sound at a bend?

The Rule 34(e) signal, one prolonged blast (Rule 9(f)).

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