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36

Signals to Attract Attention

An attention signal must not be mistaken for another prescribed signal. A searchlight may indicate danger without dazzling or confusing another vessel; required navigation lights remain displayed.

Rule 36 permits necessary light or sound signals to attract attention only if they cannot be mistaken for signals authorized elsewhere in COLREG or for an aid to navigation.

A searchlight beam may be directed toward a danger in a way that does not embarrass another vessel. Avoid high-intensity intermittent or revolving lights, such as strobe lights.

IMO COLREG 1972Official text

Full wording of the rule, reproduced from the official source below.

If necessary to attract the attention of another vessel, any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules, or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel. Any light to attract the attention of another vessel shall be such that it cannot be mistaken for any aid to navigation. For the purpose of this Rule the use of high intensity intermittent or revolving lights, such as strobe lights, shall be avoided.
Source:

Signal Workflow

Decide the context first: manoeuvring in sight, restricted visibility, or distress.

The same whistle can mean very different things in a different context.

Check both the pattern and the interval.

For fog signals, the time spacing is part of the rule, not just the blast sequence.

When vessels in sight are approaching and you do not understand the other vessel’s intentions or actions, or doubt its collision-avoiding action, immediately sound at least five short, rapid blasts (Rule 34(d)).

Exam Focus

Three short blasts are astern propulsion, not a fog signal.

Rule 35(a)–(f) signals have a maximum interval of 2 minutes; the anchor and aground signals in (g)–(h) have a maximum interval of 1 minute.

Paragraphs (i)–(j) provide small-vessel alternatives.

Key Takeaways

1

An attention signal must not be confused with a COLREG signal or aid to navigation

2

A searchlight directed toward danger must not dazzle or otherwise embarrass another vessel

3

Avoid high-intensity intermittent or revolving lights, such as strobes

Common Mistakes

Using signals that could be confused with distress signals

Test Your Knowledge

Practise this topic and review the explanation for each answer.

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Frequently asked questions about COLREG Rule 36

What signals may a vessel use to attract attention?

Necessary light or sound signals that cannot be mistaken for a COLREG signal or an aid to navigation (Rule 36). A searchlight directed toward danger must not embarrass another vessel, and high-intensity intermittent or revolving lights, such as strobes, should be avoided.

Can a searchlight be used under COLREG Rule 36?

Yes — a searchlight may be directed towards a danger to attract attention, as long as the signal cannot be mistaken for a prescribed signal or an aid to navigation.

Which attention-getting signals are not allowed?

Any signal that could be mistaken for one authorized elsewhere in these Rules or for an aid to navigation. Using something that could be confused with a distress signal is the common mistake.