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Rule 18: Responsibilities Between Vessels (COLREGS)

Last reviewed October 21, 2026

The short answer

Rule 18 is the pecking order. A power-driven vessel underway keeps out of the way of vessels not under command, restricted in their ability to maneuver, engaged in fishing, and sailing. A sailing vessel keeps out of the way of the first three, and a fishing vessel of the first two. Rules 9, 10, and 13 can override it.

The rule text

Except where Rules 9, 10 and 13 otherwise require:

International Rules, U.S. Coast Guard Navigation Rules and Regulations Handbook (NAVCEN, 2024 corrected edition), Rule 18

A power-driven vessel underway shall keep out of the way of: (i) a vessel not under command; (ii) a vessel restricted in her ability to maneuver; (iii) a vessel engaged in fishing; (iv) a sailing vessel.

International Rules, U.S. Coast Guard Navigation Rules and Regulations Handbook (NAVCEN, 2024 corrected edition), Rule 18

What it means on the water

  • Power-driven gives way to NUC, RAM, fishing, and sailing (Rule 18(a)).
  • Sailing gives way to NUC, RAM, and fishing (Rule 18(b)).
  • Fishing, when underway, keeps out of the way of NUC and RAM so far as possible (Rule 18(c)).
  • Narrow channels (Rule 9), traffic separation schemes (Rule 10), and overtaking (Rule 13) come first.
  • A seaplane on the water keeps well clear of all vessels in general, but follows the steering rules when risk of collision exists (Rule 18(e)).

International vs Inland

International Rule 18(d) asks vessels other than NUC or RAM to avoid impeding a vessel constrained by her draft showing the Rule 28 signals, and tells her to navigate with particular caution. Inland Rule 18(d) is reserved, since Inland has no constrained-by-draft status. International 18(f) covers WIG craft.

Common exam traps

  • Forgetting the opening exception. An overtaking sailboat still keeps clear (Rule 13).
  • Putting a sailing vessel ahead of a fishing vessel. Sailing gives way to fishing (Rule 18(b)(iii)).
  • Applying constrained-by-draft priority on Inland waters.

Try 3 questions on Rule 18

  1. A sailing vessel and a vessel engaged in fishing are on collision courses. Who keeps out of the way?

    1. The fishing vessel
    2. The sailing vessel
    3. Neither
    4. The one on the other's port side
    Show answer

    B. The sailing vessel Rule 18(b)(iii).

  2. A power-driven vessel meets a vessel restricted in her ability to maneuver. Who keeps out of the way?

    1. The power-driven vessel
    2. The RAM vessel
    3. Whichever is larger
    4. Neither
    Show answer

    A. The power-driven vessel Rule 18(a)(ii).

  3. Which rules override the Rule 18 pecking order?

    1. Rules 5, 6 and 7
    2. Rules 9, 10 and 13
    3. Rules 14 and 15
    4. Rule 19 only
    Show answer

    B. Rules 9, 10 and 13 Rule 18 opens with "Except where Rules 9, 10 and 13 otherwise require."

Frequently asked questions

Does a sailboat always have right of way over a powerboat?

No. Under Rule 18 a power-driven vessel keeps out of the way of a sailing vessel, but Rules 9, 10, and 13 can change that, for example when the sailboat is overtaking.

Who is at the top of the pecking order?

Vessels not under command and vessels restricted in their ability to maneuver. Everyone in Rule 18(a) to (c) keeps out of their way.

Is constrained by draft part of Rule 18 on Inland waters?

No. Inland Rule 18(d) is reserved.

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