Why this matters
Communication breaks down fastest in an emergency. A vessel in distress must be understood immediately, regardless of language or equipment. International standardisation — through SOLAS, the International Code of Signals (ICS), and the IMO Standard Marine Communication Phrases (SMCP) — exists to ensure that meaning cannot be lost in translation or panic.
Distress Signals
Annex IV of COLREGS lists the recognised distress signals. A yacht's officer must know them by rote because the examiner will ask without notice. Key signals include:
- Vocal/sound: Continuous sounding of fog signal apparatus; shouting/hailing "MAYDAY" on VHF Ch 16
- Pyrotechnic: Red parachute rocket flare; red hand flare; orange smoke (daytime)
- Visual: Slowly and repeatedly raising and lowering outstretched arms; flame on the vessel (burning tar, oil, etc.); orange canvas with black square and circle
- Electronic: DSC distress alert on VHF/MF/HF; EPIRB activation; SART/AIS-SART response to radar
- Code flags: November over Charlie (N/C)
- Morse: SOS by any means — three short, three long, three short
- Radiotelephone: The word MAYDAY
All signals carry equal legal standing — none is more "official" than another.
Urgency and Safety Signals
- Urgency (PAN-PAN): Situation is serious but vessel not in immediate danger — e.g. man overboard recovered but requiring medical assistance.
- Safety (SÉCURITÉ): Navigational or meteorological warning — e.g. unlit vessel in the traffic lane, new hazard.
The distinction matters: using MAYDAY when PAN-PAN is appropriate wastes SAR resources and may obscure a genuine distress call.
International Code of Signals (ICS)
The ICS provides a system of single-letter, two-letter, and three-letter flag hoists, phonetic equivalents, and Morse equivalents covering all essential communications. On a yacht under 3000 GT the most examined signals are:
- Alpha (A): Diver down, keep clear
- Bravo (B): Dangerous cargo
- Oscar (O): Man overboard
- Quebec (Q): Request pratique (healthy vessel, request clearance)
- Victor (V): Require assistance
The ICS is a statutory publication — it must be carried on vessels where SOLAS requires; in practice an OOW is expected to use it confidently.
IMO Standard Marine Communication Phrases (SMCP)
SMCP provides standardised English phrases for bridge-to-bridge, bridge-to-shore, and on-board communication. Its purpose is to eliminate ambiguity — particularly where one or both parties are using English as a second language. In distress communication the SMCP templates for MAYDAY, PAN-PAN, and SÉCURITÉ calls define exactly what information to transmit and in what order: identity, position, nature of distress, persons on board, any other relevant information. Knowing this structure allows an OOW to broadcast useful information under extreme stress.