Rule 35: sound signals in restricted visibility.

When does COLREGs Rule 35 apply?

In or near an area of restricted visibility, 'whether by day or night'. Rule 3(l) defines restricted visibility by its causes — fog, mist, falling snow, heavy rainstorms, sandstorms 'or any other similar causes' — not by a distance. Being near it is enough: clear weather alongside a fog bank still counts.

Unlike Rule 19, Rule 35 does not say it applies only to vessels not in sight of one another. As we read it, the signals go on when another vessel comes into view.

What are all the Rule 35 sound signals?

A short blast is about one second, a prolonged blast four to six seconds (Rule 32). 'At most every 2 minutes' below means at intervals of not more than 2 minutes, as the rule puts it; 'at most every minute', not more than one minute.

Power-driven vessel making way through the water: one prolonged blast, at most every 2 minutes — 35(a).

Power-driven vessel underway but stopped and making no way: two prolonged blasts in succession, about 2 seconds apart, at most every 2 minutes — 35(b).

Not under command, restricted in her ability to manoeuvre, constrained by her draught, sailing, fishing, or towing or pushing another vessel: one prolonged followed by two short blasts, at most every 2 minutes — 35(c).

Vessel towed (the last vessel of the tow, if more than one), if manned: one prolonged followed by three short blasts, at most every 2 minutes, when practicable immediately after the towing vessel's signal — 35(e).

Pushing vessel and pushed vessel rigidly connected in a composite unit: as a power-driven vessel, 35(a) or (b) — 35(f).

At anchor: the bell rung rapidly for about 5 seconds, at most every minute — 35(g).

At anchor, 100 metres or more: the bell rung rapidly for about 5 seconds in the forepart, then immediately the gong rapidly for about 5 seconds in the after part, at most every minute — 35(g).

At anchor, optional extra warning: one short, one prolonged and one short blast — 35(g).

Fishing at anchor, or restricted in her ability to manoeuvre and carrying out her work at anchor: one prolonged followed by two short blasts, at most every 2 minutes, instead of the 35(g) signals — 35(d).

Aground: three separate and distinct strokes on the bell, the rapid ringing of the bell, three separate and distinct strokes — plus the gong where 35(g) requires it, and optionally an appropriate whistle signal — 35(h).

12 metres or more but less than 20 metres: need not give the anchor and aground bell signals, but if not, some other efficient sound signal at most every 2 minutes — 35(i).

Less than 12 metres: need not give the Rule 35 signals, but if not, some other efficient sound signal at most every 2 minutes — 35(j).

Pilot vessel engaged on pilotage duty: may add an identity signal of four short blasts to the 35(a), (b) or (g) signal — 35(k).

What must I do when I hear a fog signal?

That is Rule 19(e). Hear a fog signal apparently forward of the beam and, unless you have determined there is no risk of collision, slow to the minimum speed at which you can hold your course, take all way off if necessary, and navigate with extreme caution until the danger of collision is over.

What does a power-driven vessel sound in fog?

Rule 35(a): making way through the water, one prolonged blast, at most every two minutes. Rule 35(b): underway but stopped with no way on, two prolonged blasts about two seconds apart, also at most every two minutes.

Underway means not at anchor, made fast to the shore or aground (Rule 3(i)) — so a power-driven vessel stopped in the water with her engines off is still underway, and gives 35(b) — unless she is not under command, when 35(c) applies.

Which vessels sound one prolonged and two short?

Rule 35(c): a vessel not under command, a vessel restricted in her ability to manoeuvre, a vessel constrained by her draught, a sailing vessel, a vessel engaged in fishing, and a vessel engaged in towing or pushing another vessel. They give it 'instead of' the 35(a) or (b) signals — so the same signal whether making way or not.

A sailing vessel is one under sail with no propelling machinery in use (Rule 3(c)). Start the engine and put it in gear and you are a power-driven vessel (Rule 3(b)), giving 35(a) or (b).

What does a vessel being towed sound?

Rule 35(e): if the tow is manned, the vessel towed — the last one, if there are several — sounds one prolonged and three short blasts, at most every two minutes, straight after the towing vessel's signal when practicable. The towing vessel herself gives the 35(c) signal, so with a manned tow a listener hears, where practicable, one prolonged and two short, then one prolonged and three short. With an unmanned tow, only the towing vessel's signal is heard.

What about a pushing vessel?

It depends on the connection. A pushing vessel and a vessel pushed ahead that are rigidly connected in a composite unit are regarded as a power-driven vessel and give 35(a) or (b) (35(f)). Otherwise the pushing vessel is a vessel 'engaged in towing or pushing another vessel' and gives 35(c).

What extra signal can a pilot vessel give?

Rule 35(k): on pilotage duty, a pilot vessel may add four short blasts, as an identity signal, to her 35(a), (b) or (g) signal. It is optional — the rule says 'may'.

What does a vessel at anchor sound in fog?

Rule 35(g): ring the bell rapidly for about five seconds, at most every minute. From 100 metres, the bell is rung forward and the gong is then sounded rapidly aft, also for about five seconds.

She may add short, prolonged, short to warn an approaching vessel of her position and of the possibility of collision.

Which anchored vessels don't ring the bell?

Rule 35(d): a vessel engaged in fishing at anchor, and a vessel restricted in her ability to manoeuvre when carrying out her work at anchor, sound the 35(c) signal — one prolonged followed by two short blasts — instead of the 35(g) bell (and gong).

What does a vessel aground sound?

Rule 35(h): the 35(g) bell — and gong, where required — framed by three separate and distinct strokes on the bell just before the rapid ringing and three just after it. An appropriate whistle signal may be added; the rule does not name one.

Do small craft have to give these signals?

Under 12 metres (35(j)): the Rule 35 signals are optional, but without them she makes some other efficient sound signal, at most every 2 minutes.

12 metres to under 20 metres (35(i)): only the anchor and aground bell signals of 35(g) and (h) are optional — the same size band in which Rule 33 requires a whistle but no bell. Without them, she makes some other efficient sound signal, at most every 2 minutes. Underway, the other Rule 35 signals still apply to her.

How might Rule 35 come up in an MCA oral?

It may come up as a signal to give or a signal to identify, inside a fog scenario. Examples of the kind of question to be ready for:

“You're on a motor yacht in fog, making way. What do you sound, and how often?”

“You stop and lose way. What changes?”

“You're sailing in fog with the engine off. What do you sound? And if you start the engine and put it in gear?”

“You hear one prolonged blast followed by two short. What could it be?”

“You hear a bell rung rapidly for about five seconds, then a gong. What is it, and roughly how big?”

“What does a 15-metre yacht at anchor in fog have to sound?”

Where do candidates go wrong on Rule 35?

The common slips: giving a sailing vessel one prolonged blast; giving the sailing signal while motor-sailing; mixing up the intervals — not more than two minutes for the whistle signals, not more than one minute for the anchor bell; confusing the stopped signal (two prolonged) with the narrow-channel overtaking signals in Rule 34(c); getting the anchor warning signal's order wrong (short, prolonged, short); forgetting the three strokes before and after the bell when aground; and having a fishing vessel at anchor ring the bell.