Rule 24(a)(i) — Tow > 200 m
NIGHT. A towing vessel shows: THREE masthead lights in a vertical line on the forward mast; sidelights; sternlight; YELLOW towing light above the...
Scenario briefing
NIGHT. A towing vessel shows: THREE masthead lights in a vertical line on the forward mast; sidelights; sternlight; YELLOW towing light above the sternlight. What does the THREE-vertical masthead configuration tell you?
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 24(a)(i): three vertical masthead lights on the forward mast = tow length OVER 200 m.
- Tow length is measured from the stern of the towing vessel to the after end of the tow.
- The towed object shows sidelights and sternlight (Rule 24(e)).
- In a long tow, the towline itself is the hidden hazard — pass well clear astern of the tow, not between tug and tow.
Common mistakes to avoid
- Cutting between tug and tow because the visible gap looks safe — the towline is invisible from a beam aspect.
- Reading three vertical masthead lights as a different vessel type entirely. The three-vertical pattern is unique to a long tow.
Why it matters
Exam relevance
Rule 24(a)(i) tow-length identification is examined in STCW OOW and Yachtmaster Offshore orals as a continuation of the standard tow recognition question.
Related scenarios
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