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SESK: Stuff Everyone Should Know · sesk.info/boat-overtaking-22-5-degrees

You count as overtaking another boat when you come up from more than how many degrees behind its beam?

22.5 degrees abaft the beam, where only its sternlight shows at night.

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  1. 45 degrees abaft the beam
  2. 10 degrees abaft the beam
  3. 22.5 degrees abaft the beam ✔

Why: Rule 13 says you are overtaking when you approach from more than 22.5 degrees behind the other boat's beam (its side). At night you'd see only its white sternlight, not its red or green sidelights.

Huh, didn't know that: If you're in any doubt whether you're overtaking, the Rules say assume you are.

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Why did the slow boat never worry? Everyone passing it had to keep clear.
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References

Answer: 22.5 degrees abaft the beam. Rule 13 says you are overtaking when you approach from more than 22.5 degrees behind the other boat's beam (its side). At night you'd see only its white sternlight, not its red or green sidelights.

  1. 33 CFR 83.13, Overtaking (Rule 13) www.ecfr.gov/current/title-33/section-83.13
    from a direction more than 22.5 degrees abaft her beam
    Checked 2026-10-09.

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Boating & WaterWhen one boat passes another from behind, which boat must keep clear?Boating & WaterAt night you see only another boat's white sternlight, no red or green. What situation is this?Boating & WaterA boat under 12 meters (39.4 feet) needn't carry a regulation whistle. What must it have?

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