Transmitting a DSC alert with vhf turned off

[jonrarit]

We have a dufour GL460 of 2018 with the standard raymarine VHF. We have been told twice now that we are tranmitting a DSC alert despite the vhf being turned off!!!

Anyone got any ideas why this is happening?



Thanks

 

[jlavery]

What sort of 'alert'? A distress alert? How have you been informed? When you say 'standard Raymarine VHF', which model?

Do you have any other devices on the boat capable of DSC transmissions? Handheld, MOB beacon etc. spring to mind.

 

[jonrarit]

Its a Ray50 transmitting a general “distress” and no we have no other transmitters on board

 

[jonrarit]

Chap just went passed 10 mins ago to advise us and i could hear his dsc alert going off. Confirmed it was us as the vhf transmits the boat name too. Checked our vhs and confirmed it was turned off

 

[jlavery]

How have you been notified of the alert?

(Threads crossed.)

Common boat name and not your boat?

 

[jonrarit]

This is the second time it has happened withthe unit off!

 

[Martin_J]

Did the receiver of these distress alerts tell you the MMSI they were originating from?.... and does that match the MMSI assigned to your vessel (or handheld devices)?

Tbh, I thought the Distress alerts contained MMSI and not your vessel name.

 

[Martin_J]

If they were seeing your vessel name, are you sure it was DSC and not an AIS proximity alarm..

Do you transmit AIS?

 

[jlavery]

This is the second time it has happened withthe unit off!

Next time, ask what MMSI number is being transmitted - as others have said, I think DSC alerts only transmit MMSI, not boat name.

Suggest you also turn VHF on, call coastguard and ask if they've received DSC alerts from you.

If you are generating spurious alerts, it's vital that the coastguard know.

 

[jonrarit]

Yes we transmit ais. The chap did ask if we were “Dory” which is our boat name whcich is now starting to make we wonder if it was an AIS transmission….but i could here his DSC alert going off in his cockpit.

Come to think of it, the first time it happened a few weeks ago the other skipper asked if we were Dory too

 

[Martin_J]

Perhaps search Marinetraffic for any MMSIs assigned to you, and for your vessel name... If you're lucky, someone else has mis-typed theirs and that's what the other vessel is seeing..

Although as you've heard it emanating from the passing vessel, a DSC alert is quite recognisable (although one usually suppresses them quick quick due to the noise).

 

[jlavery]

I really do suggest calling up the coastguard on Ch16 (or CH67). They won't bite, and will really appreciate clearing up a spurious transmission if it is occurring.

 

[jonrarit]

I would do but i am in greece and rule number one out here is “do not contact the coastguard unless someone is dying” …. Quite literally …… but thats another can of worms for a different thread

 

[jlavery]

Fair point, but a DSC mayday is telling them that someone is dying, when they are not. So I reckon it's justified.

 

[jonrarit]

The more i think about it, if it were a “distress” transmission then surely the coast guard or other boats would have responded?

 

[jonrarit]

Is it possible that the recipients have their ais proximty set to alert them as dsc sounds over their vhf?

 

[lustyd]

Fair point, but a DSC mayday is telling them that someone is dying, when they are not. So I reckon it's justified.

Most people couldn’t tell the difference between a distress and a position request coming in via DSC so don’t be so sure it’s a mayday. By the sound of it it’s probably not even DSC!

 

[jlavery]

The more i think about it, if it were a “distress” transmission then surely the coast guard or other boats would have responded?

That's my thinking too. The coastguard would be going nuts. Really sounds like AIS or something else!

Do let us know if you get to the bottom of it - it's intriguing for us (as well as being damned annoying for you).

 

[Refueler]

Yes we transmit ais. The chap did ask if we were “Dory” which is our boat name whcich is now starting to make we wonder if it was an AIS transmission….but i could here his DSC alert going off in his cockpit.

Come to think of it, the first time it happened a few weeks ago the other skipper asked if we were Dory too

If their proximity alarm is set on their AIS rcvr - then that may be the alarm they are having ...

It would be normal to switch off AIS tx when in port ....

 

[jonrarit]

Thanks for your helpful and prompt reply folks. If it happens again i will investigate further and report back. Now back to my sundowners on the foredeck