Hi Alain et al,
I agree that possibly the most reliable receiver is acually a full transceiver; it can both receive and transmit.
With regard to sea areas, the HF/SSB radio also functions as a MF radio (to receive NAVTEX and Weatherfax) for comms up to 100nm. It is relevent everywhere beyond the limited A1 coastal coverage, in sea areas A2, A3 & A4. All commercial
vessels that might venture beyond sea area A1 are required to carry a HF/SSB radio with DSC capability. That's how MRCCs (inclucing the Coast Guard) contact commercial vessels to ask them to assist in emergencies. It's also how an MRCC located beyond VHF range can contact your yacht.
The MRCC cannot keep track of all the vessels - big and small - in it's area, to call them individually. So they send a general DSC alarm
signal that wakes up the HF/SSB radio in any vessel maintaining a DSC watch in range. Then they announce the nature of the problem and location of the vessel and ask for vessels nearby to respond to them. It could be that you are the closest. But you are beyond VHF range of the MRCC station. The HF/SSB radio with DSC becomes immediately important when you move beyond range of an available A1 VHF station.
VHF radio range is line of sight and therefore quite short. A VHF handheld at deck
level has roughly a 3 to 5nm range. With a mast-top antenna you can increase it to 25nm. If you want to talk to a cruising buddy who left the day before you, to ask him the waypoints into the anchorage he's now located, or tell him you had to turn back because of a mechanical problem, you'll likely need to talk beyond 25nm at the morning or evening sked time you arranged.
A VHF A1 service
needs lots of coast stations - or repeaters/relays on coastal mountians - to make a continuous coverage for a dependable service
coverage in coastal waters. It works in some areas - like Europe/UK where population densities are high, but not in most other places of the world. That's why some countries have officially declared they have no A1 sea area service. This includes Australia
, where there is a large coastline and small population. All commercial vessels operating in open water
must have a HF/SSB radio with DSC. If you want to cruise
the Australian coast and have any chance to get weather information, contact a coast station etc, you also need a HF/SSB radio. There is no VHF shore station network, but there are big HF/SSB stations that cover all the Austalian coast line and all of Australia's huge maritime search and rescue
"Depending on the circumstances, your initial distress alert should still be made by radio if possible. You should activate your distress beacon only if contact cannot be made by any other means or when told to do so by a rescue authority.
Whilst there may be other Governments establishing HF facilities in the Indian and Pacific Ocean areas, Australia aims to cover the Australian Search and Rescue Region (SRR) to a high level of probability with its own stations. "
A similar scenario occurs throughout the Pacific and Indian Oceans and here in SE Asia
, where I live. There are almost no VHF coast stations, and commercial shipping
densities in open water
are thin; compared to Europe/UK and North America. A VHF radio is almost useless as far as calling for assistance because it's likely the nearest vessel is beyond VHF range and the MRCC is perhaps a few hundred or thousand nm distant. VHF is limited to talking to boats in the anchorage, maintianing contact with your tender
crew when they are ashore, or when sailing in close company. If you participate in a rally on this side of the world, you'll almost certainly need a HF/SSB radio.
The M700 is a great radio, but it does not have DSC capability. In Europe/UK and Australia, the minimum radio standard for a new recreational vessel installation
is an ICOM M801 (E=Europe or A=Australia). It has DSC, a BIG display screen
(so you can see the display without reading classes
and from a distance), and a radio unit that is fully sealed, without a fan, so there is no salt
air being sucked through the radio components (a primary cause of equipment
failure) and no fan draining batteries; so you can keep the radio on watch for emergency DSC alarms - or individual calls to your radio using its MMSI number - 24/7. A proper Marine HF/SSB radio like this comes with all the marine HF/SSB frequencies, channels and emergency frequiencies pre-programmed.
They can also have additional frequencies added by the user, so a HAM can add HAM frequencies and a SailMail or Winlink user can add these email
frequencies. It is legel to operate a Marine radio on HAM frequencise, but not legel to operate a HAM radio on Marine frequencies; it's to do with the technical specs of the two types of radios.
Yachts cruising the Pacific, SE Asia
and transitting the Indian Ocean
, - or in years past, sailing from SE Asia to the Red Sea - normaly setup self-help cruiser skeds. These are conducted on the HF radio, because yachts very quickly spread out beyond VHF radio range. They swap sea and weather info, arrange to pass spare parts
etc, give info about anchorges, shore contacts, where to do customs
and immigration etc. Occasionally they arrange to tow each other. There are specific marine HF/SSB frequencies designed for intership communications which they use. All this commmunication is free of charge. And when one yacht talks about a good deal on fuel
at a recent stop, all the other yachts listening on the sked get the details simmultaneously.
The HF/SSB radio becomes an important means to help minimise cruising costs, as well as provide the safety/emergency communications via the DSC system. Add SailMail (or WinLink for HAMs) and you can send/receive emails (order spare parts
, book a marina berth, talk to the person renting
your house, check your bank account etc), get emailed weather info (eg: METAREA forecasts, coastal forecasts & GRIB charts
for free - which commercial users pay heaps for through their satellite systems) and send free daily position reports for display on the web for your family and friends to see.
The HF/SSB with DSC is a smart investment for yachts venturing beyond home port VHF range.