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COLREGs · Rule 37

Distress Signals

Annex IV lists the distress signals: SOS, MAYDAY voice, NC flag hoist, square-flag-and-ball, continuous fog horn, gun fired at one-minute intervals, red star rockets, parachute red flare, hand red flare, orange smoke, slow-and-repeated arm raise/lower, EPIRB, DSC alert.

Source: 33 CFR §83.37 · COLREGs Rule 37Last verified 2026-05-16

Rule text#

Source

The international COLREGs text is published by the IMO and is not available to reproduce here. Shown below is the U.S. counterpart, 33 CFR §83.37, which tracks the international wording closely.

When a vessel is in distress and requires assistance she shall use or exhibit the signals described in Annex IV to these Rules (33 CFR part 87).

Authoritative source#

Source links checked against the current public rule corpus on 2026-05-16.

  • 33 CFR §83.37 — the section this text comes from, with its neighbours.
  • International COLREGs Rule 37 verbatim text is published by the IMO and is authoritative for international waters.

Practice this rule#

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

Which of the following is a recognized distress signal under 33 CFR Part 87?

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All COLREGs Rules of the RoadRule 32 — Sound Signal DefinitionsRule 33 — Equipment for Sound SignalsRule 34 — Maneuvering and Warning SignalsRule 35 — Sound Signals in Restricted VisibilityRule 36 — Signals to Attract AttentionInland Rule 37Practice Rule 32Practice Rule 34Practice Rule 35Practice: Rules of the Road
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COLREGs Rule 37: Distress Signals — Captain's Exam Prep · CaptainsGround