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AhaBulb: Stuff Everyone Should Know · ahabulb.com/boat-sidelight-colors

A boat's sidelights are which colors on which sides?

Green on starboard (right), red on port (left).

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  1. Red starboard, green port
  2. Green starboard, red port ✔
  3. White on both sides

Why: Inland Rule 21 puts the green sidelight on the starboard (right) side and the red on the port (left). Each shines from dead ahead to 22.5 degrees behind the beam.

Huh, didn't know that: On boats under 20 meters, both sidelights may be combined in one lantern on the centerline.

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References

Answer: Green starboard, red port. Inland Rule 21 puts the green sidelight on the starboard (right) side and the red on the port (left). Each shines from dead ahead to 22.5 degrees behind the beam.

  1. 33 CFR 83.21 Definitions, Inland Rule 21 (eCFR) www.ecfr.gov/current/title-33/section-83.21
    Sidelights mean a green light on the starboard side and a red light on the port side
    Checked 2026-10-08.

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Boating & WaterWhen must recreational boats show their navigation lights?Boating & WaterAt night you see only another boat's white sternlight, no red or green. What situation is this?Boating & WaterA sailboat moving under sail alone at night shows which lights?

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