COLREGs · Rule 30 · 33 CFR §83.30
Anchored Vessels and Vessels Aground
At anchor: forward all-round white (and a second all-round aft if 50 m+), or one ball by day. Aground: same as anchored plus two all-round red, or three balls by day.
What does Rule 30 actually say?#
Source
Practice this rule#
One real exam question on this rule, cited to source. No sign-up.
Under both the International and Inland Rules, lights shall be exhibited from ______.
How does Inland Rule 30 differ from COLREGs?#
Most of Inland Rule 30 is the international rule, but paragraphs (h) through (l) are Inland-only: they set lighting requirements for moored barges — barges projecting into a buoyed channel, barges narrowing a channel to under 80 metres, groups more than two barges wide or over 25 metres, and barges not moored parallel to the bank — along with exemptions for barges in slips, behind pierheads, in designated special anchorage areas, and in a schedule of well-illuminated areas. COLREGs Rule 30 has no barge provisions at all.
21 of 38 rules differ somewhere; the five the exam leans on are Rule 9, Rule 10, Rule 24, Rule 28 and Rule 34, side by side on Inland vs International Rules.
Why it shows up on the exam#
Vessels under 7 m at anchor not in or near a narrow channel may omit the anchor light or shape.
What does the exam actually test here?#
At anchor
Two whites, or one under 50 m
A vessel at anchor exhibits an all-round white light in the fore part and a second, lower all-round white light at or near the stern. A vessel of less than 50 metres may instead exhibit a single all-round white light where it can best be seen.
Aground
Anchor lights plus two red or three balls
A vessel aground shows the anchor lights and, in addition where they can best be seen, two all-round red lights in a vertical line by night and three balls in a vertical line by day.
The size exemptions
7 m, 12 m, 20 m
Under 7 metres at anchor, if not in or near a narrow channel, fairway, anchorage, or where other vessels normally navigate, need not show anchor lights. Under 12 metres aground need not show the two red lights or three balls. Under 20 metres at anchor in a Coast Guard designated special anchorage area need not show anchor lights or shapes.
Rule 30 — common exam questions#
What lights does a vessel at anchor show?
An all-round white light in the fore part and a second all-round white light at or near the stern, at a lower level than the forward one (33 CFR §83.30(a)).
What if the vessel at anchor is under 50 metres?
She may exhibit a single all-round white light where it can best be seen instead of the two lights (33 CFR §83.30(b)).
What does a vessel aground display?
The anchor lights, plus — if practicable, where they can best be seen — two all-round red lights in a vertical line, and by day three balls in a vertical line (33 CFR §83.30(d)).
Do you need an anchor light in a special anchorage area?
Not if your vessel is less than 20 metres in length and the area is a special anchorage designated by the Coast Guard (33 CFR §83.30(g)).
Must a vessel at anchor light her decks?
A vessel at anchor may, and a vessel of 100 metres or more in length shall, use available working or equivalent lights to illuminate her decks (33 CFR §83.30(c)).
Authoritative source#
- 33 CFR §83.30 — this section with its neighbours. 33 CFR Part 83 is public domain; checked 2026-05-16.
- COLREGs Rule 30 is published by the IMO and is authoritative internationally.
Practise this rule against the real exam.
Real exam questions. No signup, no card.
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