Attempting to make a voice distress or urgency call on an HF radio is problematic.
Ships do not maintain a voice watch. Very few coast stations maintain a 24/7 voice watch on International distress and calling frequencies.
Furthermore, the correct distress frequency for the time of day and distance to a coast station must be selected on the radio prior to transmission.
Thinking about which frequency to use, and operating the radio correctly at a time of stress is difficult for an experienced radio operator and pretty much impossible for anybody else.
HF DSC Distress Alerts Ships and Coast Stations
By contrast, a DSC capable marine transceiver can send a distress alert by simply pressing the red distress button for 5 seconds.
The radio transmits your vessel position, MMSI, the time in UTC as well as the nature of distress (if selected prior to pressing the distress button). If the nature of distress is not selected, an undesignated distress alert is sent.
All ships and coast stations within radio range receive the distress alert containing the above information.
The radio then automatically changes to the correct distress and calling frequency to permit communication with the acknowledging coast station.
A person unfamiliar with the radio can usually manage this, even a child.
When in Distress
Typically when in distress you would activate your EPIRB, then press the red distress button on both VHF and HF radios (if fitted).
The EPIRB alert is sent to the RCC (rescue coordination centre) who will then broadcast a distress relay message seeking vessels able to come to your aid.
With the EPIRB, you have to trust help will arrive. It will, but the uncertainty from not knowing is challenging.
On the other hand, if you hear the voice of a coast station operator, or even better a ship's officer saying they are on the way, that can be incredibly reassuring.
All thanks to your DSC capable HF/SSB marine transceiver!
The HF DSC distress alert will sound alarms on the bridge of ships within radio range. If a ship is able to assist, they are REQUIRED to contact RCC offering assistance. This happens before they even need to be asked.
This is a feature unique to HF DSC radio and is one of the most compelling reasons to carry a DSC capable HF/SSB radio. A Satellite Phone cannot do this!
Of course, if there are other recreational vessels fitted with a DSC capable HF/SSB radio and it is switched on, they will also receive your distress alert.
Do the right thing
If you want your HF radio to play any part in emergency communications, it absolutely has to have DSC capability. Spend the money, your life and the lives of your crew could depend upon it.
ICOM's IC-M803, IC-M802 and IC-M801E are all DSC capable.
Some ICOM IC-M802 radios previously sold exclusively in New Zealand have been modified and are NOT DSC capable. These radios have a metal plate covering the area where the DSC antenna socket is usually located.
Almost every other radio you will encounter, including ALL ham radios are NOT DSC capable.
Non DSC capable radios are great for other applications, which I will discuss in another blog post, but PLEASE do not rely on them in an emergency. They are simply not designed for it.