Rule 27(a) — NUC NOT Making Way
NIGHT. A vessel shows TWO all-round RED lights in a vertical line where they can best be seen, and NOTHING ELSE no sidelights, no sternlight, no masthea...
Scenario briefing
NIGHT. A vessel shows TWO all-round RED lights in a vertical line where they can best be seen, and NOTHING ELSE no sidelights, no sternlight, no masthead light. She is stopped in the water. Identify.
Applicable COLREG rule(s)
📸 Night recognition — 8 aspects
The same vessel rendered every 45° of aspect — bow, starboard bow, beam, quarter, stern, port quarter, beam, bow. Use this strip to learn how the lights present from each approach angle. Click any image to view full size.
Key teaching points
- Rule 27(a)(i): NUC shall exhibit two all-round red lights vertically, where best seen.
- When NOT making way: just the two red — no sidelights, no sternlight (Rule 27(a)(ii) inverse).
- Day equivalent: two black balls vertically (Rule 27(a)(iii)).
- A NUC vessel typically has lost steering or propulsion — give wide berth, she may drift unpredictably.
Common mistakes to avoid
- Reading two vertical red lights as a navigational aid (port-side channel marker for a busy harbour, etc.). NUC red-red is at MASTHEAD height; channel markers are usually low to the water.
- Approaching a NUC at close range without sounding — she may not respond and cannot move.
Why it matters
Exam relevance
The stopped-NUC pattern is a probe variation in STCW OOW orals — candidates distinguish making-way from not-making-way Rule 27(a) cases.
Related scenarios
About SkipperCheck simulators
SkipperCheck offers two browser-based maritime training simulators:
- ARPA · AIS · COLREG Bridge Simulator — 54 scenarios covering Rules 2, 5–10, 12–19, 23–30, 34 and 35.
- VHF SRC Radio Simulator — 15 scenarios: voice Mayday, DSC distress, Mayday Relay, Pan-Pan, Sécurité, routine.
Both run in any modern browser, on desktop or mobile. No install, no plugins.