COLREGs Rule 36: Signals to attract attention

Last reviewed: October 14, 2026

Rule 36 lets a vessel attract another vessel's attention with light or sound signals or a searchlight. The signals must not be mistaken for signals authorized elsewhere in these Rules or for an aid to navigation. The Inland text as given also includes bell and gong signals for vessels at anchor or aground.

Applies toAny vessel that needs to attract the attention of another vessel; the Inland text also covers vessels at anchor, vessels aground, and pilot vessels.

What it says

  1. International: Any vessel may make light or sound signals to attract attention, but they must not be mistakable for any signal authorized elsewhere in these Rules. The vessel may also point her searchlight toward the danger without embarrassing any vessel.

    “any vessel may make light or sound signals that cannot be mistaken for any signal authorized elsewhere in these Rules”

  2. International: A light used to attract attention must not be mistakable for any aid to navigation.

    “Any light to attract the attention of another vessel shall be such that it cannot be mistaken for any aid to navigation.”

  3. International: Vessels must avoid high intensity intermittent or revolving lights, such as strobe lights, when attracting attention.

    “the use of high intensity intermittent or revolving lights, such as strobe lights, shall be avoided”

  4. Inland: A vessel at anchor must ring the bell rapidly for about 5 seconds at intervals of not more than 1 minute.

    COLREGs Rule 36(g)“A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds.”

  5. Inland: A vessel aground must give the bell signal, and the gong signal if required, as prescribed in paragraph (g). It must also give three separate and distinct strokes on the bell immediately before and after the rapid ringing.

    COLREGs Rule 36(h)“shall, in addition, give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell”

  6. Inland: A vessel of 12 meters or more but less than 20 meters in length need not give the bell signals in paragraphs (g) and (h). If she does not, she must make some other efficient sound signal at intervals of not more than 2 minutes.

    COLREGs Rule 36(i)“if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes”

  7. Inland: A pilot vessel engaged on pilotage duty may sound an identity signal of four short blasts, in addition to the signals prescribed in paragraphs (a), (b) or (g).

    COLREGs Rule 36(k)“may, in addition to the signals prescribed in paragraphs (a), (b) or (g) of this Rule, sound an identity signal consisting of four short blasts”

Common questions

Can I use a searchlight to attract another vessel's attention?

Yes. A vessel may direct the beam of her searchlight toward the danger, in such a way as not to embarrass any vessel.

“or may direct the beam of her searchlight in the direction of the danger, in such a way as not to embarrass any vessel”

Can I use a strobe light to attract attention under Rule 36?

International: the use of high intensity intermittent or revolving lights, such as strobe lights, shall be avoided.

“the use of high intensity intermittent or revolving lights, such as strobe lights, shall be avoided”

Which vessels do not have to sound anchor signals in a special anchorage area?

Inland: a vessel of less than 20 meters in length, and a barge, canal boat, scow, or other nondescript craft, need not sound the paragraph (g) signals when anchored in a special anchorage area designated by the Coast Guard.

“The following vessels shall not be required to sound signals as prescribed in paragraph (g) of this Rule when anchored in a special anchorage area designated by the Coast Guard:”

The text of COLREGs Rule 36

U.S. Coast Guard, Navigation Rules and Regulations Handbook

Rule 36: Signals to Attract Attention

International (COLREGs)

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.

Inland Rules

(g)A vessel at anchor shall at intervals of not more than 1 minute ring the bell rapidly for about 5 seconds. In a vessel of 100 meters or more in length the bell shall be sounded in the forepart of the vessel and immediately after the ringing of the bell the gong shall be sounded rapidly for about 5 seconds in the after part of the vessel. A vessel at anchor may in addition sound three blasts in succession, namely, one short, one prolonged and one short blast, to give warning of her position and of the possibility of collision to an approaching vessel.

(h)A vessel aground shall give the bell signal and if required the gong signal prescribed in paragraph (g) of this Rule and shall, in addition, give three separate and distinct strokes on the bell immediately before and after the rapid ringing of the bell. A vessel aground may in addition sound an appropriate whistle signal.

(i)A vessel of 12 meters or more but less than 20 meters in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, she shall make some other efficient sound signal at intervals of not more than 2 minutes.

(j)A vessel of less than 12 meters in length shall not be obliged to give the bell signals prescribed in paragraphs (g) and (h) of this Rule. However, if she does not, shall make some other efficient sound signal at intervals of not more than 2 minutes.

(k)A pilot vessel when engaged on pilotage duty may, in addition to the signals prescribed in paragraphs (a), (b) or (g) of this Rule, sound an identity signal consisting of four short blasts.

(l)The following vessels shall not be required to sound signals as prescribed in paragraph (g) of this Rule when anchored in a special anchorage area designated by the Coast Guard:

(i)A vessel of less than 20 meters in length; and

(ii)A barge, canal boat, scow, or other nondescript craft. Signals to Attract Attention 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.

The plain-English explanation on this page was written with AI from the regulation text above and checked automatically before publishing: every quote appears in the text, every number comes from it, and a second model confirmed each statement adds nothing the text doesn't say. Regulation text current as of August 12, 2024. The regulation text governs. RegKnot is not affiliated with the U.S. Coast Guard.