Rule 30 — Anchored and aground
The lights of every anchorage at night, and the two reds that turn an anchored vessel into one aground. What each length of vessel shows, what the small-vessel exemptions really allow, what you will hear in fog, and how it comes up in an MCA oral.
Rule 30(a) and (b) set the lights and shape for a vessel at anchor, and 30(c) adds lighting her decks. Rule 30(d) covers a vessel aground. Rules 30(e) and (f) relieve small vessels of some of these signals, in limited cases.
Rule 30(a), where it can best be seen: in the fore part, an all-round white light; and at or near the stern, an all-round white light 'at a lower level' than the forward one. By day, one ball in the fore part.
Rule 30(b): a vessel of less than 50 metres in length may show a single all-round white light where it can best be seen, instead of the two. 'May' — she can still show both. As we read it, 30(b) replaces the lights only, so the ball by day still applies to her.
Annex I, section 2(k): when two are carried, the forward anchor light must be not less than 4.5 metres above the after one, and on a vessel of 50 metres or more in length the forward anchor light must be at least six metres above the hull. In practice, that difference in height is what tells you which end is which.
Rule 22 sets their minimum range as for any all-round light: three miles on a vessel of 50 metres or more, two miles on a smaller one.
Rule 30(c): lighting the decks with the available 'working or equivalent lights' is optional for any vessel at anchor, and compulsory ('shall') from 100 metres in length.
In practice, that deck lighting is often what you see first: a large, evenly lit hull showing no sidelights is the usual picture of a big ship at anchor. Confirm it with the anchor lights.
Yes — Rule 30 is the base, and several rules build on it. A vessel restricted in her ability to manoeuvre adds the Rule 30 light, lights or shape to her red-white-red or ball-diamond-ball (Rule 27(b)(iv)). A vessel engaged in dredging or underwater operations shows her 27(d) signals instead of the Rule 30 ones (27(d)(iii)). A vessel engaged in mineclearance adds her three greens or three balls to the Rule 30 signals (27(f)). A pilot vessel on duty adds the Rule 30 signals to her white over red (29(a)(iii)).
A vessel engaged in fishing also replaces the Rule 30 signals rather than adding to them: Rule 26(a) has her show only the fishing lights and shapes, 'whether underway or at anchor', so she shows no anchor lights while she is fishing.
Rule 30(d): the anchor lights of 30(a) or (b), and in addition, where they can best be seen, two all-round red lights in a vertical line. By day, three balls in a vertical line.
Annex I, section 6, makes every shape black, with a ball not less than 0.6 metre in diameter and shapes at least 1.5 metres apart vertically. A vessel of less than 20 metres may use smaller shapes, commensurate with her size, spaced correspondingly closer.
Count the reds and look for what comes with them. Aground: two all-round reds in a vertical line, with anchor lights. Not under command (Rule 27(a)): two all-round reds in a vertical line, with sidelights and sternlight only when making way through the water. Constrained by her draught (Rule 28): three all-round reds in a vertical line, with the lights of a power-driven vessel underway.
By day it is three balls for aground, two balls for not under command, and a cylinder for constrained by draught.
At anchor (Rule 35(g)): a rapid ringing of the bell lasting about five seconds, repeated at least once a minute. From 100 metres in length, the bell is rung forward and followed straight away by about five seconds of rapid gong aft. As an optional extra, she may sound short, prolonged, short to warn a vessel that is closing on her.
Aground (Rule 35(h)): the same bell — and gong, at 100 metres or more — framed by three separate, distinct strokes on the bell just before and just after each rapid ringing. A whistle signal suited to the situation may be added.
Rule 30(e): a vessel of less than seven metres in length at anchor need not show the anchor light or ball — but only when she is not in or near a narrow channel, fairway or anchorage, 'or where other vessels normally navigate'. Anchored in or near an anchorage, she shows them like anyone else.
Rule 30(f): a vessel of less than 12 metres in length, when aground, need not show the two reds or three balls of 30(d). It says nothing about the anchor lights that 30(d) also calls for.
From 12 metres up to (but not including) 20 metres, Rule 35(i) lets a vessel skip the anchor and aground bell signals — provided she makes some other efficient sound signal instead, at least every two minutes. Under 12 metres, Rule 35(j) relieves her of 'the above mentioned signals' on the same condition: if she does not give them, some other efficient sound signal at least every two minutes.
It may come up as a lights question at night, then a follow-up. Examples of the kind of question to be ready for:
“Two all-round white lights, the after one lower than the forward one, and no sidelights. What is she?”
“The same, with two all-round red lights in a vertical line. What is she now, and what does she show by day?”
“You anchor your six-metre tender overnight in a crowded anchorage. Does she need an anchor light?”
“What will you hear from a 120-metre ship aground in fog?”
“When must a vessel at anchor light her decks?”
The common slips: putting the after anchor light higher than the forward one; thinking a vessel under 50 metres may not show two anchor lights; giving the deck-lighting threshold as 50 metres instead of 100; forgetting the anchor lights on a vessel aground; reading the seven-metre exemption as covering a small boat in an anchorage; and confusing two reds with anchor lights (aground) with two reds and sidelights (not under command).
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