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Navigation lights and shapesQuestion 106 of 352

A dredge shows two green lights in a vertical line. What do they mean?

  1. An obstruction is on that side
  2. The dredge is aground
  3. The dredge is in distress
  4. Another vessel may pass on that side
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Correct answer: Another vessel may pass on that side

Green marks the safe side. Red marks the side with the obstruction.

Source: US Code of Federal Regulations (eCFR), 33 CFR Part 83: Inland Navigation Rules, § 83.27 Vessels not under command or restricted in their ability to maneuver (Rule 27)

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Questions last reviewed: 18 October 2026