3.8 Communications, Distress Signals & SAR

When Seamanship Becomes a Radio Problem

A Master who can run a Williamson turn but freezes on the microphone still fails the casualty. Q161 Deck Safety (and related Rules distress material from Annex IV / Rule 37) expects you to choose the right priority call, use VHF Channel 16 correctly, know DSC and visual signals, and bring SAR into the problem early. On a COI passenger vessel, every extra minute of silence is extra minutes with dozens of people at risk.

VHF Channel 16 — Distress, Safety, and Calling

VHF CH 16 (156.8 MHz) is the international distress, safety, and calling channel. Operating rules that matter under stress:

• Monitor 16 when the radio is on and you are underway (as required for the vessel’s service).
• Make distress and urgency traffic on 16 (and via DSC distress if equipped).
• Keep routine chatter off 16; after contact, move to a working channel when the Coast Guard or the other station directs.
• Speak slowly, clearly, with plain language; use prowords correctly.

Handheld VHFs in the grab bag should be waterproofed, charged, and tested on a schedule — fixed radios die with ship’s power.

Mayday, Pan-Pan, Securite

Mayday format essentials (voice):

1. Mayday ×3
2. This is [vessel name / call sign] ×3 (or clearly repeated)
3. Position (lat/long, bearing/distance from a known point, or last fix + time)
4. Nature of distress (sinking, fire, medical, etc.)
5. Assistance required and number of persons aboard
6. Other useful info (injuries, intention to abandon, EPIRB activated)
7. Over — then listen

If you must abandon, send the Mayday while the radio still works. Update SAR when the situation changes (fire under control, person recovered, abandoning now).

False distress is a federal offense and a Q100/Q161 ethics trap: never practice Mayday on a live distress frequency; never fire red flares for celebration.

Digital Selective Calling (DSC)

Modern fixed VHFs often include DSC. A properly configured DSC radio holds your MMSI and can send a distress alert with position when interfaced to GPS. Exam-level points:

• Program the MMSI correctly; an unprogrammed DSC radio may not send a useful alert.
• Distress button procedure (cover, press and hold as the unit requires) sends a digital distress; follow with voice Mayday on 16 when able.
• DSC urgency/safety alerts exist for lower priorities — know that distress is the red-button case.
• DSC does not replace lookout, good seamanship, or visual signals when a nearby vessel can see you.

EPIRB / PLB devices alert satellites and SAR with identity and position when activated. Register them; mount EPIRBs for automatic release as the vessel requires; take a PLB into the survival craft if that is the plan.

Visual and Sound Distress Signals

Link this section to Rule 37 / Annex IV knowledge from Rules of the Road:

Commonly tested signals include:

• Gun or other explosive signal fired at intervals of about one minute
• Continuous sounding of any fog-signal apparatus
• Red star rockets/shells
• SOS (... --- ...) by any method
• Spoken Mayday by radiotelephone
• International Code flags NC
• Square flag with a ball above or below it
• Flames on the vessel (as from a burning tar barrel — classic list item)
• Rocket parachute flare or hand red flare
• Orange smoke signal
• Slowly and repeatedly raising and lowering arms outstretched to each side
• Signals from EPIRB / approved radio apparatus

Day vs night carriage requirements for recreational-style visual distress signals appear on captain exams; inspected passenger vessels carry the outfit required by their COI and Subchapter rules. Practical master habits: keep flares in date, dry, and accessible; know orange smoke for day and red flares for night as classic pairs; use pyrotechnics when a rescuer can actually observe them.

Continuous fog signal as distress is a high-yield trap: in restricted visibility you already sound Rule 35 signals for navigation — but continuous sounding of the fog apparatus is listed as a distress signal under Annex IV when you need assistance. Context and the full signal set matter on multi-choice stems.

Notify Authorities and Stay in the System

As soon as a real emergency exists:

• Alert U.S. Coast Guard via VHF 16 / DSC (or cellular 911 in nearshore cases as a supplement, not a full substitute for marine distress procedure).
• Give accurate persons-on-board, including passengers and crew — your headcount discipline from daily operations feeds SAR math.
• If you resolve the emergency, cancel or downgrade the distress so SAR does not risk lives searching for a problem that is over.
• Notify company/owner per SMS after life safety traffic is handled.

AMVER and SAR Coordination Awareness

SAR (Search and Rescue) is coordinated in U.S. waters primarily by the Coast Guard, which assigns search patterns, on-scene coordinators, and assisting units (cutters, aircraft, good Samaritans).

AMVER (Automated Mutual-Assistance Vessel Rescue System) is a global ship-reporting system that helps SAR planners know which merchant ships are near a distress so they can be diverted to assist. Master 100 candidates are not expected to run an AMVER office, but you should understand:

• Large commercial ships may be AMVER participants and can be tasked to divert.
• Your job in a small-passenger distress is to make a clear, early, accurate call so the SAR mission controller can vector any nearby resource — Coast Guard, other state assets, or commercial traffic.
• If you are the assisting vessel, take SAR direction on communications, search pattern, and on-scene coordination; do not freestyle a conflicting search that blanks radar/radio discipline.

Storm, Wreck, and Special Signals — Exam Overview

Beyond pure Mayday, exams may touch special signaling themes:

• Storm / weather warnings may be disseminated by broadcast (NOAA Weather Radio, Coast Guard broadcasts) and by visual storm warning displays at some shore stations (day shapes / night lights historically used for small-craft, gale, storm, hurricane warnings). Know that weather safety can justify Securite traffic when you must warn others of an immediate navigational weather hazard.
• Wreck marking and navigation hazards are primarily ATON / chart problems, but a master discovering a new wreck or floating container should report it (Coast Guard / Notice to Mariners chain) and may use safety traffic so others avoid the hazard.
• Distress vs urgency vs safety misclassification is the classic fail: a grounded vessel not flooding and not breaking up may start as Pan-Pan and upgrade to Mayday if the hull fails or weather turns.
• Inland/near-coastal small passenger masters should also know company emergency call trees and that passenger accountability is part of every radio report.

Radio discipline card for the Master 100 bridge

1. Identify the priority: Mayday / Pan-Pan / Securite.
2. CH16 + DSC (if fitted) with position and persons.
3. Visual/sound signals when they help nearby eyes and ears.
4. Update and cancel as the truth changes.
5. Obey SAR when they coordinate the scene.

That card, plus Annex IV recognition, is the communications half of Deck Safety emergencies — the half that brings helicopters and cutters while you still fight the fire, the flood, or the person in the water.