COLREG / ARPA / AIS Bridge Rule 30(a) Rule 30(d) 🔒 Course / Premium

Rule 30 — Anchored / Aground Lights

NIGHT. You see a stationary vessel showing: a single all-round WHITE light in the fore part; a second all-round WHITE light at or near the stern, lower...

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Scenario briefing

NIGHT. You see a stationary vessel showing: a single all-round WHITE light in the fore part; a second all-round WHITE light at or near the stern, lower than the forward one; and TWO all-round RED lights in a vertical line. Sidelights and sternlight NOT shown. What is her status?

Applicable COLREG rule(s)

Rule 30(a) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

Rule 30(d) — referenced in this scenario. Practising this scenario reinforces correct application under realistic time pressure.

📸 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.

Vessel at anchor viewed head-on (bow aspect) — COLREG Rule 30 night-recognition diagram — Bow

Vessel at anchor viewed from her starboard bow — COLREG Rule 30 night-recognition diagram — STBD bow

Vessel at anchor viewed from her starboard beam — COLREG Rule 30 night-recognition diagram — STBD beam

Vessel at anchor viewed from her starboard quarter — COLREG Rule 30 night-recognition diagram — STBD qtr

Vessel at anchor viewed dead astern (stern aspect) — COLREG Rule 30 night-recognition diagram — Stern

Vessel at anchor viewed from her port quarter — COLREG Rule 30 night-recognition diagram — Port qtr

Vessel at anchor viewed from her port beam — COLREG Rule 30 night-recognition diagram — Port beam

Vessel at anchor viewed from her port bow — COLREG Rule 30 night-recognition diagram — Port bow

Key teaching points

Rule 30(a)(i): vessels at anchor shall exhibit one all-round WHITE light in the fore part, where best seen.
Vessels of 50 m or more shall also exhibit, at or near the stern and at a lower level than the forward light, an all-round white light.
Vessels of less than 50 m MAY exhibit a single all-round white light where best seen.
Day equivalent: one black ball in the fore part (Rule 30(a)(ii)).

Common mistakes to avoid

Skipping the anchor light because the harbour is "well-lit" — Rule 30 is mandatory regardless of background lighting.
Hoisting the anchor light at masthead level instead of fore-part — Rule 30 specifies the forward position.

Why it matters

Anchor lights are the most-broken Rule 30 in pleasure-craft fleets — yachts moored in anchorages routinely forget the all-round white light, with predictable Rule 30 implications. Recognising anchor lights in port approaches separates moored craft from moving traffic.

Exam relevance

Rule 30(a) is a near-universal oral question in RYA Day Skipper, Coastal Skipper, Yachtmaster and STCW OOW exams.

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