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Green, flat-topped, cylinder-shaped buoys are called what?

Can buoys.

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  1. Nun buoys
  2. Spar buoys
  3. Can buoys ✔

Why: 33 CFR 62 says can buoys are cylindrical. Green cans mark the port (left) side of a channel when heading in from sea.

Huh, didn't know that: Green port side beacons on posts use square daymarks, matching the flat can shape.

The dad joke
What do you call a can opener that doesn't work? A can't opener.
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References

Answer: Can buoys. 33 CFR 62 says can buoys are cylindrical. Green cans mark the port (left) side of a channel when heading in from sea.

  1. 33 CFR 62.23 Beacons and buoys (eCFR) www.ecfr.gov/current/title-33/section-62.23
    Can buoys have a cylindrical shape.
    Checked 2026-10-08.
  2. 33 CFR 62.25 Lateral marks (eCFR) www.ecfr.gov/current/title-33/section-62.25
    Beacons have green square daymarks, while buoys are green can or pillar buoys.
    Checked 2026-10-08.

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