COLREGs Rule 37: Distress signals for vessels needing assistance
Last reviewed: October 14, 2026
Rule 37 covers signals for a vessel in distress. A vessel that is in distress and requires assistance must use or exhibit the signals described in Annex IV. The Inland rule adds a high intensity flashing white light.
Applies toVessels in distress that require assistance, under both the International and Inland rules.
What it says
International: A vessel in distress that requires assistance must use or exhibit the signals described in Annex IV to these Regulations.
“signals described in Annex IV to these Regulations.”
Inland: A vessel in distress that requires assistance must use or exhibit the signals described in Annex IV of these Rules (33 CFR part 87).
“When a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV of these Rules (33 CFR part 87)*.”
Inland: The text describes a high intensity white light flashing at regular intervals from 50 to 70 times per minute, and marks it as inland only.
“A high intensity white light flashing at regular intervals from 50 to 70 times per minute.”
Common questions
What signals must a vessel in distress use?
A vessel in distress that requires assistance must use or exhibit the signals described in Annex IV.
“When a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV of these Rules (33 CFR part 87)*.”
How do inland distress signals differ from international ones?
The inland distress signals are the same as the international ones, except for the high intensity flashing white light, which is inland only.
“*The distress signals for inland waters are the same as those displayed on the facing page for international waters, with the exception of this high intensity flashing white light.”
How fast does the inland distress white light flash?
It is a high intensity white light flashing at regular intervals from 50 to 70 times per minute.
“A high intensity white light flashing at regular intervals from 50 to 70 times per minute.”
The text of COLREGs Rule 37
U.S. Coast Guard, Navigation Rules and Regulations Handbook
Rule 37: When a vessel is in distress and requires assistance she shall use or exhibit the
International (COLREGs)
signals described in Annex IV to these Regulations.
Inland Rules
When a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV of these Rules (33 CFR part 87)*. A high intensity white light flashing at regular intervals from 50 to 70 times per minute. Inland only. *The distress signals for inland waters are the same as those displayed on the facing page for international waters, with the exception of this high intensity flashing white light.
Sections it refers to
- 33 CFR part 87
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.