COLREGs · Rule 36 · 33 CFR §83.36

Signals to Attract Attention

Any vessel may, if necessary to attract another's attention, make light or sound signals that cannot be mistaken for a signal authorized elsewhere in the rules, or direct the beam of her searchlight in danger's direction (without embarrassing other vessels).

What does Rule 36 actually say?#

Source

Verbatim 33 CFR §83.36, public domain. The international COLREGs text is published by the IMO and cannot be reproduced here; this U.S. wording tracks it closely.

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.

Practice this rule#

One real exam question on this rule, cited to source. No sign-up.

Fueling procedures and pollution prevention

Signed copies of the declaration of inspection must be retained by vessel and facility operators for at least ______.

How does Inland Rule 36 differ from COLREGs?#

COLREGs Rule 36 carries a sentence the Inland text omits, directing that the use of high-intensity intermittent or revolving lights, such as strobe lights, shall be avoided when attracting attention. Otherwise the two read the same, and note that under the Inland Rules a high-intensity flashing white light is separately a distress signal.

21 of 38 rules differ somewhere; the five the exam leans on are Rule 9, Rule 10, Rule 24, Rule 28 and Rule 34, side by side on Inland vs International Rules.

Why it shows up on the exam#

Rule 36 is the permission to improvise, bounded twice: whatever you use must not be mistakable for a signal authorised elsewhere in the Rules, and it must not embarrass another vessel.

What does the exam actually test here?#

What it allows
Light or sound signals of your own
If necessary to attract the attention of another vessel, any vessel may make light or sound signals that cannot be mistaken for any signal authorised elsewhere in the Rules.
The searchlight
Aimed at the danger
A vessel may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel.
The two limits
Not mistakable, not embarrassing
Both constraints are in the rule text. A signal that could be read as a manoeuvring signal, a distress signal, or a navigation light fails the first; a searchlight swept across another bridge's windows fails the second.

Rule 36 — common exam questions#

What signals may you use to attract attention?

Any light or sound signals that cannot be mistaken for a signal authorised elsewhere in the Rules, or the beam of a searchlight directed toward the danger in such a way as not to embarrass any vessel (33 CFR §83.36).

Can you use a strobe light to attract attention?

COLREGs Rule 36 directs that high-intensity intermittent or revolving lights such as strobes be avoided; the Inland text omits that sentence, but under the Inland Rules a high-intensity flashing white light is itself a distress signal, so using one to attract attention risks being read as a distress call.

Can you shine a searchlight at another vessel?

You may direct the beam in the direction of the danger, but the rule qualifies it: in such a way as not to embarrass any vessel. Blinding another bridge team is not attracting attention.

Authoritative source#

33 CFR §83.36 — this section with its neighbours. 33 CFR Part 83 is public domain; checked 2026-05-16.
COLREGs Rule 36 is published by the IMO and is authoritative internationally.

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