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SESK: Stuff Everyone Should Know · sesk.info/boat-power-under-12m-lights

A powerboat under 12 meters (39.4 feet) may show which lights instead of the full set?

An all-round white light and sidelights.

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  1. Only a flashing yellow light
  2. Two red lights in a vertical line
  3. An all-round white light and sidelights ✔

Why: Larger power-driven vessels show a masthead light, sidelights and a sternlight. Under 12 meters, Rule 23 lets you combine the white lights into one all-round white light, plus red and green sidelights.

Huh, didn't know that: This option combines the masthead and stern white lights into one all-round light.

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Why did the boat's light stay up all night? It was an all-rounder.
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References

Answer: An all-round white light and sidelights. Larger power-driven vessels show a masthead light, sidelights and a sternlight. Under 12 meters, Rule 23 lets you combine the white lights into one all-round white light, plus red and green sidelights.

  1. 33 CFR 83.23, Inland Navigation Rule 23 www.ecfr.gov/current/title-33/section-83.23
    A power-driven vessel of less than 12 meters in length may ... exhibit an all-round white light and sidelights.
    Checked 2026-10-09.

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