AIS query.

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peterandjeanette

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I have a Raymarine AIS transceiver on board.

Whilst out on the seas I notice that the message " NO AIS " appears without warning in the corner of my chart plotter ( E80 ). Seems to work ok continously when near land but get offshore by about 30 miles and it becomes intermittent. This has only started happening this year, or I have only noticed it this year.

Bad contact somewhere? Then why does it work ok near land? I've checked all connection where possible.
Poor reception areas in the Med? Problem connected with the VHF? Also Raymarine. Or are the VHF and AIS not connected at all?

Boat is based in mainland Spain, used for trips to Mallorca,Ibiza etc..
 
Just a thought. When you are out 30 miles, are there any other vessels about? Is the unit therefore telling you that it has received no AIS signals or is this a malfunction warning? As I don't have a Ray plotter I'm not familiar with the messages that might appear.
 
Hi Piers. Nice to know you are still around.
Things have moved on a lot since the good ol' days with Picard eh?

The worrying thing was that the AIS does not always show vessels in the area when I know they should be transmitting especially at night, eg large container vessels.
Perhaps I should call them up and ask if they are receiving my signal.

Wasn't it Winston Churchill who said we should pray to God and trust in radar or was that pray for radar and trust in God?

Fair winds

Peter
 
peterandjeanette said:
Hi Piers. Nice to know you are still around.
Things have moved on a lot since the good ol' days with Picard eh?

The worrying thing was that the AIS does not always show vessels in the area when I know they should be transmitting especially at night, eg large container vessels.
Perhaps I should call them up and ask if they are receiving my signal.

Wasn't it Winston Churchill who said we should pray to God and trust in radar or was that pray for radar and trust in God?

Fair winds

Peter
Click to expand...

Yes, still around, and now resident in Guernsey.

We had huge fun, didn't we, on those great MBM cruises. Agreed about AIS. It's v intermittent and just shouldn't be used for col avoidance yet so many folk seem to be going down that route.

If ever you come to Beaucette, give us a call. You can contact us through our website: www.playdeau.com

See you soon?

Piers and Lin
 
I think their AIS implementation is horrible. There is no way to detect that your set has not picked up a valid AIS signal other than the simple expedient of checking for a message from a ship closeby.

But, do check if you've an aerial splitter that the splitter isn't detecting a VHF carrier from a faulty VHF set.

Edit: You are a mobo? so the transmit and receive aerials (presume they are separate) will be fairly low. 6 to 8miles range might be as good as you can get?
 
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peterandjeanette said:
The worrying thing was that the AIS does not always show vessels in the area when I know they should be transmitting especially at night, eg large container vessels.
Perhaps I should call them up and ask if they are receiving my signal.
Peter
Click to expand...

Belfield Chart Plotter software cannot display class B AIS data (they are working on a fix). I could not understand why the local ferry and some yachts failed to show on the chart. "Our version of Chart Plotter displays ships, class A AIS. Smaller vessels, class B are not displayed. We are currently working on a version to display both" . Fortunately the Navicom receiver does display all AIS targets which I can see using Navmon's radar display.

As far as No AIS signal messages - what else would you expect to be displayed if the receiver is not picking up a signal because you are out of range of a vessel or base station? (unless it is like Belfield's problem)
 
ianj99 said:
As far as No AIS signal messages - what else would you expect to be displayed if the receiver is not picking up a signal because you are out of range of a vessel or base station? (unless it is like Belfield's problem)
Click to expand...

From the Raymarine manual :- No AIS = " AIS unit not available. I.e. not connected or off ".

A large container vessel only 2 miles away and a tanker 3 miles away (by radar) must be in range. But no AIS received.

However I note that the manual also states " If your own boat's position is lost the display will disable the AIS functionality and will display the " No AIS" icon." Something to check on next voyage.
 
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ianj99 said:
Belfield Chart Plotter software cannot display class B AIS data (they are working on a fix).
Click to expand...

That's just what I want! .... WITHOUT the fix ..... so that in the Solent AIS becomes useful once more the way it was before everyone started fitting ClassB transponders.

Does anyone one know if any other yachty chartplotter software (preferably free) has the facility to turn ClassB display on/off ?? I know Seaclear doesn't; what about OpenCPN?
 
VicMallows said:
That's just what I want! .... WITHOUT the fix ..... so that in the Solent AIS becomes useful once more the way it was before everyone started fitting ClassB transponders.

Does anyone one know if any other yachty chartplotter software (preferably free) has the facility to turn ClassB display on/off ?? I know Seaclear doesn't; what about OpenCPN?
Click to expand...

Well now's the time to get a copy of it before they fix the issue! £69 inc all 800 UK raster charts - it is great value.

It does seem as if the transponders could do with more sophisticated firmware. A local fishing boat was reported to be at the North Pole last week. I was amazed to be receiving a signal ostensibly from 91N 181W, range 1988nm until I saw the vessel name and number (TT137) so not sure why this was happening. Could be somewhat alarming considering the vessel was probably less than a mile away.
 
ianj99 said:
A local fishing boat was reported to be at the North Pole last week. I was amazed to be receiving a signal ostensibly from 91N 181W, range 1988nm until I saw the vessel name and number (TT137) so not sure why this was happening. Could be somewhat alarming considering the vessel was probably less than a mile away.
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Would be even more alarming if it happened the other way around, perhaps telling you some huge US aircraft carrier, actually somewhere in the Pacific, was bearing down on you!
 
Have been playing with OpenCPN quite a lot recently and have not found a way to configer AIS very much and no way of selecting class A only

The prototype weather routing looks good but still has bugs.
 
VicMallows said:
That's just what I want! .... WITHOUT the fix ..... so that in the Solent AIS becomes useful once more the way it was before everyone started fitting ClassB transponders.

Does anyone one know if any other yachty chartplotter software (preferably free) has the facility to turn ClassB display on/off ?? I know Seaclear doesn't; what about OpenCPN?
Click to expand...
The recent boom in Class B AIS transponders on yachts in the Adriatic has driven me to suppressing all AIS CPA alarms due to spurious false alarms, which is a pity as it was invaluable against the cowboy fast ferry drivers here and on one occasion gave me the name of one, coming straight at me at 33 knots, to call on VHF.

I proposed to the OpenCPN developers on the cruiser forum for a Class B target filter for CPA alarms, which went down like a lead balloon. Someone here made a more acceptable proposal of having a speed filter for both classes - anything below, say, 10 knots - but I didn't press that one.
 
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