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Rule 25: Sailing Vessels Underway and Vessels Under Oars (COLREGS)

Last reviewed October 21, 2026

The short answer

Rule 25 says a sailing vessel underway shows sidelights and a sternlight. Under 20 meters she may combine them in one masthead lantern. She may add all-round red over green at the masthead, but not with the combined lantern. A vessel motorsailing shows a cone, apex downward, by day.

The rule text

the upper being red and the lower green, but these lights shall not be exhibited in conjunction with the combined lantern permitted by paragraph (b) of this Rule.

International Rules, U.S. Coast Guard Navigation Rules and Regulations Handbook (NAVCEN, 2024 corrected edition), Rule 25

A vessel proceeding under sail when also being propelled by machinery shall exhibit forward where it can best be seen a conical shape, apex downwards.

International Rules, U.S. Coast Guard Navigation Rules and Regulations Handbook (NAVCEN, 2024 corrected edition), Rule 25

What it means on the water

  • Sidelights and sternlight (25(a)).
  • Under 20 meters: tricolor lantern at or near the top of the mast allowed (25(b)).
  • Optional red over green all-round, not with the tricolor (25(c)).
  • Under 7 meters, or under oars: show the lights if practicable, or have a white light ready in time to prevent collision (25(d)).
  • Motorsailing: cone apex downward (25(e)).

International vs Inland

Inland 25(e) says a vessel under 12 meters isn't required to show the motorsailing cone, but may. Inland 25(d) also allows a vessel under oars or a small sailing vessel to exhibit an all-round white light as an option.

Common exam traps

  • Showing red over green with a tricolor.
  • Forgetting the cone when motorsailing in International waters.

Try 3 questions on Rule 25

  1. Optional masthead lights for a sailing vessel?

    1. Green over red
    2. Red over green
    3. White over red
    4. Red over white
    Show answer

    B. Red over green Rule 25(c).

  2. Day shape when motorsailing?

    1. Ball
    2. Cone apex downward
    3. Cone apex upward
    4. Diamond
    Show answer

    B. Cone apex downward Rule 25(e).

  3. Max length for a tricolor lantern?

    1. Under 12 m
    2. Under 20 m
    3. Under 50 m
    4. Any
    Show answer

    B. Under 20 m Rule 25(b).

Frequently asked questions

Can a sailboat show a tricolor and red over green?

No (Rule 25(c)).

Do small sailboats need lights?

Under 7 meters, if practicable; otherwise a white light ready to show in time (Rule 25(d)).

Inland difference?

Under 12 meters, the motorsailing cone is optional Inland (Inland 25(e)).

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