VHF DSC

J

john_morris_uk

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We are thinking about changing the VHF to one with DCS bells and whistles etc. A friend has just advised me along the lines of 'whatever you do, get one with a separate DCS controller. Otherwise when you are off watch you can't stop the b****y think sounding its alarm every 15 minutes. He said it was especially bad in France and it has lead him to sailing with the VHF turned off.

The idea of a separate DCS controller was that you could just turn that bit off. What do people think? I have sailed boats with DSC in this country and only rarely heard the alarm go - and usually for something important. What are other peoples experiences?

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Same here, have only heard it go off 1-2 times a year. Unable to justify having seperate units.

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Have to say that is all a tad wrong.
Certaily with our stand alone DSC/radio units they are powered from the Radio and you can not switsh off the DSC half and leave the radio on.

You would have to unconect it from the rear of the radio, not recomended.

Am sure this would be the same for the Simrad.

Regards

<hr width=100% size=1>Jon Brooks Icom UK Ltd. 01227 741741
 
I have the Simrad two box set up (actually Navico, but the same except for the badge and the case colour) of RT64 and DSC1400. The DSC box is powered by an umbilical which comes from the mic socket on the front of the transceiver. The mic then transfers to a socket on the front of the DSC controller. To turn off the DSC, you need to unplug the umbilical from the transceiver, unplug the mic from the controller, replug the mic to the transceiver. No great problem, but a lot of hassle.

FWIW, I reckon we hear about 2 or 3 DSC alerts per weekend day in the Solent/Portland CG areas. Mostly these are securité msgs from the CG; in fact I think I've yet to hear a DSC-originated SOS call. Be aware, if you go the Simrad 2-box route, that there is no volume control on the DSC alert tone. You have a choice of very noisy or very noisy. Such that, the first time it went off in Berthons, Lymington, a dockie came to check us out because he thought it was a burglar alarm.

<hr width=100% size=1><A target="_blank" HREF=http://www.writeforweb.com/twister1>Let's Twist Again</A>
 
DSC is ok in the Solent, but try crossing Lyme Bay when some moronic Andrew issues a firing range DSC alert every 15 minutes. Drives you nuts.

I'd like to get my hands on the eedjit who decreed that there shouldn't be a volume control on the alert tone.

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I think if I was sinking or on fire and i pushed the red button it would be nice to know that the boats all around me with DSC are alarming loudly rather than me dying because someone half a mile away decided to turn the volume down!

I know it can be a pain but it could save a life one day and it could be one of us!

Regards

<hr width=100% size=1>Jon Brooks Icom UK Ltd. 01227 741741
 
The next stage would be to have a UID (Unique ID) for each message - you could then acknowledge a message as 'read' - and when re-issued you wouldnt be woken up.

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I think I might be concerned that all around me might have switched their sets off altogether!

We haven't yet heard this problem in anger having only just gone DSC, but I can imagine it being a pain if as Tome says it can go every 15 mins for a firing alert in Lyme Bay. We are just 2 on board and with one asleep and one up top a constant attention seeker like that will probably have me reaching for the 'off' switch PDQ. I might just use the handheld up top if that is the case. Crying wolf always did have negative results as the story goes!

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Jon

I have to disagree with you on this issue. I fear (as others have said) that people will switch off rather than endure the constant loud alarms. I resorted to switching off the DSC and using the hand-held on the Lyme Bay crossing, as suggested elsewhere.

There is no way I could keep it switched on for a night crossing with crew attempting to sleep. Much better to have a volume control - at least then you have a chance of being heard.

I think your industry is plain wrong on this, and fear that it could cost rather than save lives.

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The message format is specified in ITU recommendation M493-10 and sadly doesn't allow for a UID, which is a shame. The same recommendation simply states that 'An audible alarm and visual indicator should be provided upon reception of a distress call' so I guess that it must be the manufacturers who have added the requirement that such an alarm shall be blood-chilling and unrelenting.

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I agree with you on this Tom. At the moment the only way, in most instances, that tiresome alerts irrelevant to the vessel's current operation can be easily put into the background is to turn the radio off so that not even a CH16 watch can be maintained.

We carry both VHF and HF DSC with no declared Sea Area for either so the concept of our relying or not relying on other DSC equipped pleasure vessels in an emergency has exercised my mind. Tiresome DSC alerts are obviously not a problem here but having sailed adjacent to naval exercises with gunnery practice alerts being transmitted on CH16, I can certainly forsee the problem.

Reliance on small pleasure vessels intercepting and finding themselves having to manage a distress or urgency alert in a declared Sea Area A1 is counter intuitive to the concept of declaring the Sea Area in the first place. It is very unlikely that in a declared Sea Area A1 that an alert will not be intercepted by the responsible shore station but only intercepted by a small pleasure vessel. Also all alerts on CH70 immediately revert to CH16 once intercepted by the responsible Sea Area A1 shore station so any nearby pleasure vessel monitoring CH16 but not CH70 (due to the alarm volume being turned down too low or the DSC being disabled for the sake of quietness) will still be heard.

On at least some international Icom VHF sets (the IC-M502 for example) the DSC watch can be disabled so that a CH16 only watch can be maintained if one so wishes. In my view, all sets aimed at the pleasure market should at least have the volume of the emergency alarm adjustable to suit the current noise levels, operations and crewing of the vessel. Failing that the DSC watch should be able to be disabled (worst case that though).

John



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It is a while since I read the new ITU standard for the revised Class D but I do not recall any requirement for a "blood chilling and unrelenting" alarm in that either.

John

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John

Interesting perspective. So far I've only found the DSC to be a nuisance in one area, so I normally sail with it enabled. If this trend spreads to other areas I'm sure that we will see more and more sailors disbaling in the only way they can - by switching off their sets.

This is in no-ones interest, and I've decided that I will put in a call to Portland CG (local to Lyme Bay) next time this happens to explain that I am unable to continue to maintain a radio watch due to alarm levels and requirements for safe manning of the vessel. It will be interesting to hear their response!

Tom

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Mike

Try sailing across Lyme Bay during one of these sessions and then tell me what you think. I do believe you will have second thoughts. The DSC shrill got me every time it went off, and it didn't do much for my wife's nerves either.

At a reduced volume I would still easily hear it and I repeat my belief that this is just a plain daft requirement which should be revised for the leisure market. It may look like a great idea on paper, but if people start to switch off then are you still sure it's such a good idea?

Tom

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Well guess we will have to agree to disagree :o))).
It is the IMO who make the rules.
We just have to follow them.
That is us as the radio makers and you and I as the end users.
It is to late for either to change it.

Mind you at 38kts on a Rib I tend not to hear it anyway :o))

Hand on heart I think it will save lives.

Regards

<hr width=100% size=1>Jon Brooks Icom UK Ltd. 01227 741741
 
I switched our set off yesterday since there was a continuous carrier on 16 out in Poole Bay/West Solent. An alarm repeating every 15mins at night (repeated message) as Tome heard with crew trying to sleep would have me too reaching for the off switch PDQ. This is an entirely different scenario to a big ship bridge (there shouldn't be people asleep there though who knows nowadays) or a RIB, we cruise 2 up and off watch rest is very important to safety.

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on my icom set the alarm also goes off when you make any outgoing call. a nasty experience when your head is a foot from the box. b*****y stupid software design. icom are notorious for selling boxes with half-tested software.

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Ouch!!!!!!!

You seem to to know our kit netter than i so no need for me to relpy!
:o))))

Regards

<hr width=100% size=1>Jon Brooks Icom UK Ltd. 01227 741741
 
Sounds like the IMO have drafted the rules with only commercial shipping with 24hr manned bridges and somnabulent watchkeepers in mind; that's all very well but doesn't do us leasure boaters any good. As has already been pointed out, non-adjustable alarms will cause most folk to just switch off, with obvious potential consequences.

cheers,
david

<hr width=100% size=1>What we are dealin' with here is a complete lack of respect for the law....
 
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