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sven-olof 14th July 2019 20:35

MF intership today?
Just wonder. Perhaps missed something but are there not anymore any form of traditional MF SSB coms betewen ships ?

Or is all coms digital ?

For example when looking at Marintetraffic at oilfields out Northsea with all those support vessels around. I suppose VHF in short distances but how do they comunicate at distances? Are there any open digital channels ? for company or safety communication.

R651400 15th July 2019 04:59

Possibly the last 2182 khz RT distress frequency watch-keeping in Western waters was by the USCG and discontinued around 2013 but as far as I know the band is still allocated for marine use and equipment still available. See here

Bill.B 15th July 2019 09:43

2301khz used to be the frequency of choice for UK/Irish intership comms in the North Sea, Channel and Irish Sea home trade areas. Cant remember what the times were. 6pm rings a bell. No idea if it is still used.

BobDixon 15th July 2019 11:18


Originally Posted by sven-olof (Post 2991893)

Or is all coms digital ?

I think the first answer is that maritime comms are still analogue. So SSB and FM are just as they've always been.

Whether there are still company nets, and such like, on the intership frequencies I don't know. And, of course, for those within range of the coast, the mobile phone services have taken a load of the traffic.

sven-olof 17th July 2019 20:04

Thanks for replies. There must been a lot of those comms in the far ears of Stonhaven and between rigs and Barges on the way. Heard it myself far in Sweden in the 70ts.

I have tried to read about actual allocations and there is MF frequencies.
Would be interesting to hear from any CG or mariners active today.

All the best

majoco 19th July 2019 01:23

But who are you going to get to operate them? None of us Sparkies any more, maybe the "Electronics Officer" has an operators certificate of some sort.

How many times have you been called out to the bridge wing to work the Aldis lamp to call "what ship" to that set of lights on the horizon? I guess the navigators have had to smarten up their morse!

Navtex is about the only thing I've heard the MF band on 512kHz. Here Taupo Marine radio listens on a few frequencies ( but there's no CW any more - only a couple of US nostalgia stations are active occasionally. I guess most ships are listening on VHF Channel 16 but everyone has Satcom to 'phone home' and GMDSS for when the SHTF.

J. Davies 19th July 2019 02:24

Still Sailing after 45 years here....No. Nobody uses SSB intership anymore. Sorry. That is dead. VSAT, Iridium and simple mobile phone when within range is all that is required now. WhatsApp is king on here!

Searcher2004 19th July 2019 09:23

There's certainly still (ship to ship?) voice traffic in the old 2MHz marine/amateur band, as down here in Norfolk I often hear very strong SSB signals in non-English languages and other stations with heavily-accented Scots. I would guess they are mostly fishing vessels as there is often a loud engine or other machinery sound in the background.

On a similar topic, does anyone know if SITOR is still in use on the HF marine bands? I have been playing with a old PK232MBX modem which does NAVTEX well but as the amateur AMTOR mode is very rarely heard these days SITOR might work if I knew where to listen.



R651400 19th July 2019 16:24

Didn't think the Scottish inshore fishermen would give up their beloved "135" (metres) so quickly!
Thanks for the info.

duncs 21st July 2019 00:34


Originally Posted by R651400 (Post 2992721)
Didn't think the Scottish inshore fishermen would give up their beloved "135" (metres) so quickly!
Thanks for the info.

R651, what does that mean? I remember as a youngster, listening to the trawler band. I'm an ex RO, but I don't understand that!

Searcher2004 21st July 2019 05:03

135 metres equates to 2221kHz, was that a popular trawler frequency?

I've been doing a bit of research into the use of "wireless" by the RNLI and in their house magazine they often quote wavelength in metres as opposed to frequency in kc/s.



PS: have a look at this quirky piece.

R651400 21st July 2019 05:53

2222 kcs (135 metres) from memory was the one and only UK ship to ship allocation on the entire RT band and you can imagine when the mode was AM only absolute mayhem 24/24..

Searcher2004 21st July 2019 06:05


Originally Posted by R651400 (Post 2992975)
2222 kcs (135 metres) from memory was the one and only UK ship to ship allocation on the entire RT band and you can imagine when the mode was AM only absolute mayhem 24/24..

Yes, all those carriers beating together and producing warbly heterodynes!

R651400 21st July 2019 07:00

Certainly was and frequently the NE inshore fishermen would wander on to a ship to shore channel to escape the mayhem but not for long as Stonehaven GND as well as its coast station RT frequencies also had all the ship to shore channels to chase them back to the "135 !"
Happy days.

Searcher2004 21st July 2019 11:27


Originally Posted by R651400 (Post 2992987)
Certainly was and frequently the NE inshore fishermen would wander on to a ship to shore channel to escape the mayhem but not for long as Stonehaven GND as well as its coast station RT frequencies also had all the ship to shore channels to chase them back to the "135 !"
Happy days.

I have a Coastal Radio 91/MX small craft AM station that I'm hoping to get operational for 160 metre band use. The transmitter has 2182 (crystal not fitted) plus 2534, 2301, 2246 and 2009 kc/s. 2182 was distress but can you recall what the other four channels were used for? I'm pretty sure 2246 was ship/shore.



BobDixon 21st July 2019 13:22


Originally Posted by Searcher2004 (Post 2992971)
135 metres equates to 2221kHz, was that a popular trawler frequency?

Going back to the days of wavelength and crystal conrol, "the 135" was 2226kHz. Very well used by fishermen for intership. There were other intership channels which fishing vessels used but in Scotland they almost always monitored 2226Khz (and seldom 2182) - so much so that 2226kHz was a frequency installed at Wick Radio GKR where, prior to making any Mayday Relay broadcast, procedure was to make an announcement on 2226KHz advising vessels to tune to 2182 for the broadcast.

King Ratt 21st July 2019 14:49

When I at the age of 17 joined our local lifeboat, the coxswain would phone Charlie George Holyhead just prior to launch. He was always told we will hear you on 137.5 when you are afloat.

Bob McManamon 22nd July 2019 08:43

MF intership communications are still possible on any of the intership frequencies listed in the Radio Regs, or any of those nominated by individual national administrations. But mostly the operators do not know how to set up a call. if you don’t have a pre-arranged contact time, it is necessary to call the other vessel by DSC, indicating the frequency you are going to use for follow-up RT. Unfortunately, the MF/HF DSC channels are only for Distress, Urgency and Safety purposes, and Routine calls are prohibited. But a ship could still call another ship by sending the DSC call with a Safety Category, and then follow up with RT on a non-distress frequency. Radio Regs regard GMDSS equipment test calls as a “Safety” matter and selection of the Safety Category is automatic for “push-button” test calls, but there is no reason why an intership Safety call can't be made manually. In such a case, you would be testing both your DSC and radiotelephone. It’s easy when you know how.

Varley 22nd July 2019 09:59

I don't think DSC is banned for commercial or intership non-safety related calls. It is just that the DSC facilities for distress and safety traffic must be dedicated.

(Any ticketed responses?)

Ron Stringer 22nd July 2019 10:14

I have been out of the CCIR/ITU/IMO loop for a couple of decades now but I recall that 2187.5 kHz was designated as the mandatory DSC distress and safety alerting/watchkeeping frequency for GMDSS Area 2 (within MF range of a shore station) and 2177.0 kHz was the DSC calling frequency for other, routine, calls to ships or shore stations.

How that has worked out in practice I don't know.

Paul Braxton 22nd July 2019 23:29

#18 : Good to see you on forum, Bob.

Alan Couchman 22nd July 2019 23:36

Hi Roger. A listing of all the British MF frequency allocations is given here: Wireless World, May 1953:, on Page 94 (214): Maritime Frequency Changes. The frequencies you mention are all allocated to British coasters and deep sea ships: 2009 & 2534 for ship to shore with 2241 and 2301 for ship to ship.

All the best, Alan

sparkie2182 22nd July 2019 23:41

Some archive material there!!!!!


R651400 23rd July 2019 07:36

#22 .. A lot more UK inter-ship channels than I was aware of.
Thanks for the link (in modern parlance "awesome") and thanks for posting.

Bob McManamon 25th July 2019 02:09

Use of the GMDSS for "Routine" purposes
Hi Paul!!
And ….hmmm. Yes Varley, you are right about Routine calls not being banned. Quite the reverse: special arrangements were made for “Routine” calls from the very beginning. All DSC calls have to include a “Category” – Distress, Urgency, Safety or Routine. Incidentally, the original DSC performance standards included “Ships Business” “to cater for shore-to-ship communications having priority category 6 as defined in Radio Reg 4441”. However, “Ships Business” was abolished as a Category in the GMDSS when ITU-R M.492-11 (the 11th version of DSC performance standards) was published in 2004. But the history of GMDSS operating procedures and performance standards has had a long and tortured history, not to mention labyrinthine, so I will give the reasons for my earlier comment.

DSC calls on VHF Ch.70 (the DSC Distress frequency) may be legitimately made using all four of those Categories, therefore ship-ship Routine DSC calling is permissible on VHF and it is easy to go to an intership channel (e.g. Ch.77) for follow-up radiotelephone comms.

DSC calls on MF/HF may be made either on the DSC Distress and Safety Frequencies (which unlike VHF are reserved for those purposes only) or on one of the many “Routine” frequencies which were allocated so that the DSC unit could be used to automatically set up RT calls to shore subscribers. This seemed like a good idea at the time, but no-one foresaw the rapidity of the onset of satellite communications and this DSC “Routine” system for RT calls was never used in practice – at least not to any significant extent. If any members know of a nation which actually offered this service, I’d be interested to hear about it.

Anyhow, these DSC “Routine” calling channels on MF/HF use a two-frequency mode similar to the two-frequency RT channelling used for radiotelephone calls, so ships cannot communicate with other ships, only with the coast stations. There is a single exception to this: one DSC frequency (2177 kHz) has been allocated for “Routine” (intership) DSC calling in the MF band.
Today most ships, if not all, only install MF/HF DSC units having the six Distress and Safety frequencies. Very few DSC units have a second watchkeeping series for “Routine” calls. The use of the “Routine” category on the DSC MF/HF Distress and Safety frequencies has always been prohibited by regulation, and the option to select a “Routine” category on those frequencies was designed out of the equipment in 2007 by ITU-R M.493-12 (DSC performance standards version 12) to ensure that operators do not select it by mistake. That is why I am saying that it is still OK to call another ship on the DSC Distress and Safety frequencies provided that you select the Safety Category.

In other words, if you are not going to follow up with a Safety (SECURITE) Message, it is still legal to call an individual ship on MF/HF DSC using the Safety Category if your intention is to test your equipment with another vessel. This can be done automatically (provided the other ship has not disabled its automatic “test acknowledgement” function) but it can also be done manually, in which case it is possible and permissible, and preferable, to nominate an intership voice frequency for follow-up communication. STCW (Navigation and Radio Watch) requires the DSC to be tested on air at least once a week.

It is often more convenient to make the test call automatically via a GMDSS shore station which records the call on a computer. If you want to test the radiotelephone by speaking with a shore operator it would be necessary to compose a DSC call manually using the Safety category and then use the radiotelephone on the HF Distress and Safety frequency (having listened for a few minutes beforehand to make sure there is no distress, urgency or safety traffic already in progress). The function tables in ITU-R M.493-11 (2004) confirmed that the “Test” and “Test Acknowledgement” calls were available on Ships DSC equipment Classes A/B, D and E. The current version - M.493-15 (2019) – has added DSC Class H, and Class M (which can test with own ship but not the other way round). This is what I mean by a “labyrinthine” history. We are now on the 15th iteration of DSC performance standards.

The best publication for everyday GMDSS users is ALRS Vol.5. Everything is explained and it is kept up to date by weekly corrections.

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