Question 1

When reporting your position to the Coastguard during an emergency, what is the most useful and unambiguous format?

Accepted Answer

Latitude and longitude in degrees and decimal minutes (e.g. 50°24.5'N 001°32.1'W) OR bearing and distance from a known charted landmark (e.g. "2.5nm south-west of the Needles lighthouse") Two unambiguous position formats the Coastguard can immediately act on: 1) Lat/long in degrees and decimal minutes — what your GPS displays; 2) Bearing and distance from a charted mark ("2.5nm SW of the Needles"). Avoid relative descriptions ("we're near a sandbank") and OS grid references (land-based). Confirm which format the Coastguard prefers and have your GPS position ready before calling.

Question 2

What is the primary purpose of DSC (Digital Selective Calling) on a VHF radio?

Accepted Answer

To send a digitally coded distress alert containing the vessel's MMSI and position automatically to all DSC-equipped stations and the Coastguard DSC is a digital signalling system that allows a vessel to send a distress alert with MMSI, position, and nature of distress (if programmed) in one button press. The alert is received by the Coastguard and all DSC-equipped vessels in range. Channel 70 is dedicated to DSC; voice distress uses Ch 16.

Question 3

What is an MMSI number and why must it be programmed into a DSC radio before it is used?

Accepted Answer

Maritime Mobile Service Identity — a unique 9-digit number identifying the vessel; without it a DSC distress alert cannot identify the vessel to rescuers MMSI is a unique 9-digit identifier (UK leisure vessels: 235 prefix) that must be programmed into the DSC controller. When a distress alert is sent, the MMSI is transmitted and the Coastguard can immediately look up the vessel's details, including description, contact numbers, and registered position. An unprogrammed or wrongly programmed MMSI delays rescue.