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RulesAtSea

Free boating rules practice

Sound signals quiz: manoeuvring and fog signals

Read the visibility and encounter context, then listen to the complete signal at normal speed. An accessible timed sequence is available for every sound. Identify what the signal communicates without assuming a vessel type or manoeuvre that the sound does not prove.

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14 concepts · explained answers · no account needed

Practice scope: Free, original supplementary practice using International COLREGs / IRPCS and separately labeled IALA Regions A and B. These are authored learning questions, not official examination questions or a qualification. Use the full applicable rules, current charts and local requirements on the water. International COLREG signals. US Inland manoeuvring and overtaking exchanges differ and are outside these exercises.

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Question topics and explained answers

The quiz draws from these 14 concepts. Recognition questions may change the viewing aspect, whistle or day/night cue. Open a topic to review its explanation and governing reference.

One short blast

What does this sound signal communicate in the stated context?

Two vessels are in sight in open water. A power-driven vessel underway sounds a manoeuvring signal under International Rules.

One short blast Altering course to starboard.

A power-driven vessel underway, in sight of another vessel, announces a manoeuvre authorised or required by the rules.

Rule 34(a) · US Coast Guard · International Navigation Rules
Two short blasts

What does this sound signal communicate in the stated context?

Two vessels are in sight in open water. A power-driven vessel underway sounds a manoeuvring signal under International Rules.

Two short blasts Altering course to port.

A power-driven vessel underway, in sight of another vessel, announces a manoeuvre authorised or required by the rules.

Rule 34(a) · US Coast Guard · International Navigation Rules
Three short blasts

What does this sound signal communicate in the stated context?

Two vessels are in sight in open water. A power-driven vessel underway sounds a manoeuvring signal under International Rules.

Three short blasts Operating astern propulsion.

A power-driven vessel underway, in sight of another vessel, announces a manoeuvre authorised or required by the rules. This describes propulsion, even while the vessel retains forward motion.

Rule 34(a) · US Coast Guard · International Navigation Rules
Overtaking on her starboard side

What does this sound signal communicate in the stated context?

In a narrow channel, a vessel coming up astern proposes an overtaking passage that requires the vessel ahead to make room.

Overtaking on her starboard side Request passage on the overtaken vessel’s starboard side.

In sight in a narrow channel or fairway, when the vessel ahead must take action to permit safe passing. Agreement does not transfer the overtaker’s duty to keep clear.

Rules 9(e)(i), 34(c)(i) · US Coast Guard · International Navigation Rules
Overtaking on her port side

What does this sound signal communicate in the stated context?

In a narrow channel, a vessel coming up astern proposes an overtaking passage that requires the vessel ahead to make room.

Overtaking on her port side Request passage on the overtaken vessel’s port side.

In sight in a narrow channel or fairway, when the vessel ahead must take action to permit safe passing. Agreement does not transfer the overtaker’s duty to keep clear.

Rules 9(e)(i), 34(c)(i) · US Coast Guard · International Navigation Rules
Overtaking agreement

What does this sound signal communicate in the stated context?

In a narrow channel, the vessel ahead answers a proposal from a vessel wishing to overtake.

Overtaking agreement Consent to the proposed overtaking passage.

In sight in a narrow channel or fairway, when the vessel ahead must take action to permit safe passing. Agreement does not transfer the overtaker’s duty to keep clear.

Rules 9(e)(i), 34(c)(ii) · US Coast Guard · International Navigation Rules
At least five short, rapid blasts

What does this sound signal communicate in the stated context?

Two vessels in sight are approaching. One vessel sounds a signal; interpret the complete sequence.

At least five short, rapid blasts Doubt about intentions, actions or collision avoidance.

Approaching vessels in sight of one another. Sound immediately when the other vessel’s intentions or sufficient action are in doubt.

Rule 34(d) · US Coast Guard · International Navigation Rules
Bend or obstruction warning

What does this sound signal communicate in the stated context?

A vessel approaches a channel bend where an intervening obstruction may hide another vessel.

Bend or obstruction warning A vessel is approaching obscured water.

Nearing a bend or obstruction in a channel or fairway where another vessel may be hidden.

Rule 34(e) · US Coast Guard · International Navigation Rules
Reply from behind the bend

What does this sound signal communicate in the stated context?

After hearing a warning from around an obscured channel bend, another approaching vessel sounds this reply.

Reply from behind the bend An approaching vessel answers the warning.

An approaching vessel within hearing around the bend or behind the intervening obstruction.

Rule 34(e) · US Coast Guard · International Navigation Rules
Power-driven vessel making way

What does this sound signal communicate in the stated context?

In restricted visibility, a vessel out of sight sounds her operating signal. Interpret the complete sequence.

Power-driven vessel making way Power-driven and moving through the water.

In or near restricted visibility, by day or night. The signal gives operating information; it does not establish a stand-on vessel. Repeat at intervals of not more than 120 seconds.

Rule 35(a) · US Coast Guard · International Navigation Rules
Power-driven vessel stopped

What does this sound signal communicate in the stated context?

In restricted visibility, a vessel out of sight sounds her operating signal. Interpret the complete sequence.

Power-driven vessel stopped Underway, stopped and making no way through the water.

In or near restricted visibility, by day or night. The signal gives operating information; it does not establish a stand-on vessel. Repeat at intervals of not more than 120 seconds.

Rule 35(b) · US Coast Guard · International Navigation Rules
Shared special-operation fog signal

What does this sound signal communicate in the stated context?

In restricted visibility, a vessel out of sight sounds her operating signal. Interpret what the complete sequence establishes.

Shared special-operation fog signal NUC, RAM, draught-constrained, sailing, fishing, towing or pushing.

In or near restricted visibility, by day or night. The signal gives operating information; it does not establish a stand-on vessel. These operations share this signal; hearing it cannot identify which vessel type is present. Fishing at anchor and RAM carrying out work at anchor also use it. Repeat at intervals of not more than 120 seconds.

Rule 35(c), (d) · US Coast Guard · International Navigation Rules
Manned vessel being towed

What does this sound signal communicate in the stated context?

In restricted visibility, a first vessel sounds and a second source follows with this sequence. Interpret the second signal.

Manned vessel being towed The manned tow, or last manned vessel of a tow.

In or near restricted visibility, by day or night. The signal gives operating information; it does not establish a stand-on vessel. When practicable, follows immediately after the towing vessel’s signal. Repeat at intervals of not more than 120 seconds.

Rule 35(e) · US Coast Guard · International Navigation Rules
At anchor: bell

What does this sound signal communicate in the stated context?

In restricted visibility, a metal sound comes from a vessel nearby. Interpret the complete sequence.

At anchor: bell A vessel at anchor.

In or near restricted visibility, by day or night. The signal gives operating information; it does not establish a stand-on vessel. Rapid bell ringing for about five seconds. Vessels 12–20 m may instead make an efficient sound every two minutes; smaller vessels have a similar alternative. Repeat at intervals of not more than 60 seconds.

Rule 35(g), (i), (j) · US Coast Guard · International Navigation Rules

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