COLREGs · Rule 27
Vessels Not Under Command or Restricted in Their Ability to Maneuver
Last verified: 2026-05-16
TL;DR
NUC: two all-round red in a vertical line + two balls by day. RAM: red-white-red vertical + ball-diamond-ball by day. Mineclearing, dredging, divers — each has a distinct light/shape combination.
Why it shows up on the exam
Rule 27 is the rule with the most distinct shape combinations in the entire book.
Authoritative source
Source links checked against the current public rule corpus on 2026-05-16.
- 33 CFR §83.27— verbatim Inland Rule text (US Code of Federal Regulations)(retrieved 2026-05-16)
- International COLREGs Rule 27 verbatim text is published by the IMO. The Inland counterpart 33 CFR §83 chunk above mirrors the international wording almost verbatim.
Inland parallel
Inland Rule 27 — Vessels Not Under Command or Restricted in Their Ability to Maneuver →More from Part C — Lights and Shapes
Related drills
- Rule 20 — Application (Lights and Shapes)
- Rule 21 — Definitions (Lights)
- Rule 22 — Visibility of Lights
- Practise Rule 23 — Power-driven Vessel Underway
Drill COLREGs Rule 27
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