Your vessel receives a MAYDAY relay on Ch 16. The distress vessel is 45nm away. Your vessel can reach the position in 4 hours. What are your obligations?

A. RECEIVING DISTRESS — SOLAS V/33 OBLIGATIONS: SOLAS V/33 — OBLIGATION TO RENDER ASSISTANCE: "The master of a ship at sea which is in a position to be able to provide assistance, on receiving a signal from any source that persons are in distress at sea, is bound to proceed with all speed to their assistance." THIS IS A LEGAL OBLIGATION — not discretionary. OBLIGATIONS: (1) PROCEED AT FULL SPEED toward the distress position; (2) ACKNOWLEDGE: acknowledge the MAYDAY relay on Ch 16 — "MAYDAY — [distress vessel name] — THIS IS [your vessel] — RECEIVED MAYDAY — PROCEEDING TO ASSIST — OVER"; (3) INFORM: inform your own MRCC of your action and ETA; (4) COMPANY: notify DPA — they need to know the vessel is diverting. Commercial considerations do not override the legal obligation to assist; (5) ASSESS: is there another vessel closer? Check VHF for other responses to the MAYDAY. If multiple vessels respond, the SAR authority (MRCC) will designate the On Scene Coordinator (OSC) — often the nearest vessel; (6) IF UNABLE TO ASSIST: if proceeding is impossible (breakdown, own vessel emergency, too far), the master must notify the MRCC explaining why; (7) RELEASE FROM DUTY: only released from the obligation to assist by the master of the distress vessel, the SAR authority, or by your vessel being excused by a higher authority (MRCC). You CANNOT simply decide 4 hours is too far.

B. At 45nm, you are too far away to render effective assistance. Acknowledge the MAYDAY and continue on your planned voyage — the coastguard will coordinate SAR.

C. Check with your company DPA before diverting — commercial voyages require company authorisation before any unplanned deviation from the planned voyage.

D. Acknowledge the MAYDAY relay and advise the distress vessel's MRCC of your position. SOLAS V/33 only requires acknowledgement — not actual diversion.

A. DSC DISTRESS ALERT — VHF PROCEDURE: DSC (Digital Selective Calling) on VHF Channel 70 is the primary GMDSS distress alerting mechanism. PROCEDURE: (1) ENSURE POSITION IS UPDATED: the DSC controller must have a current GPS position input (most modern sets auto-update from GPS). Verify the position shown is current; (2) OPEN THE DSC CONTROLLER: navigate to the distress function — typically a protected button (lift cover or press and hold to prevent accidental activation); (3) SELECT NATURE OF DISTRESS: most DSC controllers allow selection of distress nature — UNDESIGNATED, FIRE, FLOODING, COLLISION, GROUNDING, LISTING, SINKING, DISABLED AND ADRIFT, ABANDONING SHIP. If time permits, select the correct nature; (4) TRANSMIT: press/hold the distress button for the required duration (typically 5 seconds with button confirmation). The controller transmits the DSC distress call on Ch 70 — this broadcasts your MMSI, position, time, nature of distress to all vessels in range and to coast stations; (5) SWITCH TO CH 16: immediately after DSC transmission, switch VHF to Ch 16 and transmit the voice MAYDAY message; (6) MAYDAY VOICE: "MAYDAY MAYDAY MAYDAY — THIS IS [vessel name × 3] — MAYDAY [vessel name] — POSITION [lat/lon] — [NATURE OF DISTRESS] — [POB] — [ANY OTHER RELEVANT INFO] — OVER"; (7) AWAIT ACKNOWLEDGEMENT: coast stations and vessels will acknowledge on Ch 16.

B. The DSC distress alert is transmitted on Ch 16. Tune the VHF to Ch 16, press the distress button, and speak the MAYDAY message directly.

C. Voice MAYDAY on Ch 16 must be transmitted first — then the DSC alert follows. The voice call alerts nearby vessels who may not be monitoring DSC.

D. DSC distress is only for MF/HF radio. VHF uses the traditional voice MAYDAY on Ch 16 only — VHF DSC is not a required GMDSS function.

A. NAVTEX — SYSTEM AND OOW USE: NAVTEX (Navigational Telex) is an automated system that broadcasts maritime safety information (MSI) on 518 kHz (international) and 490 kHz (national language) using NBDP (Narrow Band Direct Printing). WHAT IT PROVIDES: (1) NAVIGATIONAL WARNINGS (B messages): hazards to navigation — wrecks, buoy off station, new obstructions, pilot areas, lights changed; (2) METEOROLOGICAL WARNINGS (W messages): gale warnings, storm warnings, weather bulletins; (3) PILOT SERVICE MESSAGES (P messages); (4) ICE REPORTS (I messages); (5) SAR INFORMATION (D messages): distress messages, SAR operations in the area; (6) SUBFACTS and NAVFACTS: submarine exercise areas and other military notifications. HOW IT WORKS: NAVTEX stations broadcast on a schedule. Each station has a unique letter identifier. The NAVTEX receiver is programmed to receive messages from stations covering your sea area. Messages not relevant to the vessel's area can be filtered. OOW DUTIES: (1) Ensure NAVTEX is switched on and printing; (2) Check the NAVTEX receiver is set to receive messages from stations in the current sea area; (3) READ ALL MESSAGES as they print; (4) Bring significant messages (navigational warnings, gale warnings, SAR in the area) to the master's attention; (5) CHART PLOT: plot navigational warnings on the chart/ECDIS; (6) Do NOT ignore NAVTEX messages — they contain safety-critical information.

B. NAVTEX operates on VHF Ch 68 and provides local port information for vessels within 20nm of the coast. It is only relevant when approaching port.

C. NAVTEX is a backup to weather fax and provides only meteorological information. Navigational warnings are only available through the vessel's AIS.

D. NAVTEX messages should be collected and reviewed once per watch. Urgent messages are highlighted in red and require immediate action; all others can wait.