COLREGs – Sound Signals

15 January 2026 5 min read Bridge, Latest Articles, Navigation, Watchkeeping

Intent, warning, and why ignoring sound signals still causes collisions

Use the links below to jump to any section:

Why Sound Signals Still Matter
What Sound Signals Are Legally Meant to Do
Manoeuvring Signals in Sight of One Another
Sound Signals in Narrow Channels
Sound Signals in Restricted Visibility
The Difference Between Intention and Warning
Sound Signals and COLREGs Authority
Common Misuse and Dangerous Assumptions
Radar, AIS, and Sound: How They Must Work Together
When You Hear Signals but See Nothing
When the Other Vessel Uses Sound Incorrectly
Sound Signals During Pilotage and Manoeuvring
Why Sound Signals Are Often Ignored on Modern Bridges
Typical Accident Patterns Involving Sound Signals
Practical Sound Signal Discipline for OOWs

1. Why Sound Signals Still Matter

Sound signals are often treated as obsolete on modern bridges.

This is a serious error.

Sound signals exist because there are times when:

visibility is degraded
electronic information is incomplete
visual identification is delayed
intent must be communicated immediately

Sound cuts through uncertainty.

When sound signals are ignored, bridges lose one of the last layers of collision defence.

2. What Sound Signals Are Legally Meant to Do

Sound signals serve two distinct purposes:

Manoeuvring intention (what I am about to do)
Warning / presence (where I am, especially when unseen)

They are not suggestions.
They are legal signals recognised under COLREGs.

Failure to use or respond appropriately can be used as evidence of poor seamanship.

3. Manoeuvring Signals in Sight of One Another

When vessels are in sight of one another in confined or close-quarters situations, sound signals communicate intended manoeuvres.

Key principles:

sound signals announce your action — they do not ask permission
signals must be made before the manoeuvre
signals must be clear, correct, and timely

Common failures include:

sounding after altering course
sounding “out of habit” without manoeuvring
assuming AIS intentions replace sound

Sound signals only work if actions follow immediately.

4. Sound Signals in Narrow Channels

In narrow channels, sound signals are particularly important because:

manoeuvring space is limited
bank effects reduce control
overtaking situations develop quickly

Sound signals here act as early warnings, not last-second alerts.

If you wait until close quarters, the signal has already failed.

5. Sound Signals in Restricted Visibility

Restricted visibility is where sound signals regain primary importance.

In fog, heavy rain, snow, or sandstorms:

visual confirmation may be impossible
radar contacts may be ambiguous
AIS data may lag or be incorrect

Sound signals serve to announce:

your presence
your type of vessel
your operational status

They are not optional — they are expected behaviour.

6. The Difference Between Intention and Warning

One of the most misunderstood aspects of sound signals is this distinction:

Intention signals say what I am about to do
Warning signals say pay attention — danger exists

Confusing the two leads to dangerous assumptions.

Never assume that hearing a signal means agreement.

Sound does not equal consent.

7. Sound Signals and COLREGs Authority

Sound signals do not override COLREGs.

They support them.

If another vessel sounds an incorrect signal:

you are not obligated to follow it
you must still avoid collision
Rule 2 responsibility remains

A wrong sound signal does not transfer liability — but ignoring it may.

8. Common Misuse and Dangerous Assumptions

Repeated sound-signal failures include:

using sound to “assert right of way”
sounding without manoeuvring
not sounding because “radar shows CPA is fine”
assuming small craft will respond correctly
failing to sound due to bridge complacency

Sound signals are preventative tools, not formalities.

9. Radar, AIS, and Sound: How They Must Work Together

Sound signals must be integrated with:

radar target analysis
visual lookout
AIS awareness

Sound fills the gap between detection and certainty.

If radar says something is there but you cannot identify it, sound signals help reduce ambiguity.

10. When You Hear Signals but See Nothing

This is a high-risk condition.

If you hear sound signals and cannot visually identify the source:

assume restricted visibility rules apply
reduce speed early
avoid close-quarters situations
increase CPA margins
call the Master early

Do not wait for visual confirmation.

Sound signals exist precisely because visual confirmation may not arrive in time.

11. When the Other Vessel Uses Sound Incorrectly

If another vessel:

sounds late
sounds incorrectly
sounds but does not manoeuvre

You must assume:

confusion on the other bridge
potential misinterpretation of the situation
increased collision risk

Respond with space and time, not argument.

12. Sound Signals During Pilotage and Manoeuvring

During pilotage:

sound signals remain valid
the Master remains responsible
pilots may expect sound discipline

Failure to sound correctly during manoeuvring is often highlighted in post-incident reviews.

Sound signals reinforce shared awareness — especially in busy port approaches.

13. Why Sound Signals Are Often Ignored on Modern Bridges

Common reasons include:

over-reliance on electronics
noise pollution in busy waters
lack of recent fog experience
cultural habits (“nobody uses them”)

This does not reduce their importance.

It increases the risk when they are needed.

14. Typical Accident Patterns Involving Sound Signals

Investigation patterns show:

restricted visibility collisions at excessive speed
sound signals not made or not interpreted
bridges waiting for radar certainty
delayed Master calls

Sound signals are often mentioned not because they were wrong — but because they were absent.

15. Practical Sound Signal Discipline for OOWs

A professional OOW treats sound signals as:

early tools, not late warnings
supplements to visual and radar information
legally meaningful actions

Good practice includes:

knowing signals instinctively
sounding early when unsure
reducing speed before sounding in fog
documenting restricted visibility procedures
calling the Master early

Sound signals do not replace judgement — they support it.