Raymarine C120 classic plotter and AIS

My boat has a C120 classic with a Raymarine AIS 250 receiver. The AIS 250 has it's own a built in multiplexer.The system works well, and I cannot detect any 'slowing down' but this could be due to the lack of targets in the Med.
With this combination, it is necessary to have a SeaTalk GPS as the only NMEA input to the C120 is used by the AIS250 at 38Kps.

Steve
 
whiteshythe said:
prv said:
These two sentences seem to contradict each other :)

Pete[/QUOTE
Pete , as far as I am aware, the C120 will not accept NMEA GPS signals at a baud rate of 38Kps in addition to the Fast Heading info.
However, I I am happy to be proved wrong.

Steve.
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I think Pete is saying that if the GPS signal is fed into the C120 through Seatalk you don't need the multiplexer ..... just connect the AIS unit at high speed directly to the C120.

Richard
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RichardS said:
I think Pete is saying that if the GPS signal is fed into the C120 through Seatalk you don't need the multiplexer
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No :)

I was saying that if the AIS has a built-in multiplexer, then you can connect an NMEA GPS to it and the combined signal will be fed into the plotter. But Steve has explained why that might not actually be the case.

Seems like an odd limitation, but not wholly surprising as AIS and 38k NMEA were a bit of a novelty when these units were designed :)

Pete
 
prv said:
No :)

I was saying that if the AIS has a built-in multiplexer, then you can connect an NMEA GPS to it and the combined signal will be fed into the plotter. But Steve has explained why that might not actually be the case.

Seems like an odd limitation, but not wholly surprising as AIS and 38k NMEA were a bit of a novelty when these units were designed :)

Pete
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OK .... but why do you even need the multiplexer if the GPS is Seatalk?

Richard
 
This has been discussed before, see http://www.ybw.com/forums/showthread.php?443407-C120-NMEA-inputs-AIS-etc&highlight=c120+and+ais

As per that thread

Have done this with a Comar AIS. Basically feed the Raymarine Raystar 125 GPS NMEA into the Comar which multiplexes and sends AIS and position data to the C120 plotter, which is set to 38400 baud. As you know it only has one NMEA input.

I took a second connection from the output side of the Raystar 125 to the VHF which works fine.

The only downside is that the AIS needs to be on to get position data to the plotter. This means that anywhere near port I need to switch off my AIS alarm as other wise it sound continuously.

This set up does not need a stand alone multiplexer, which keeps things simple.

It works fine even in busy trafffic areas,
 
Finbar said:
Have done this with a Comar AIS. Basically feed the Raymarine Raystar 125 GPS NMEA into the Comar which multiplexes and sends AIS and position data to the C120 plotter, which is set to 38400 baud. As you know it only has one NMEA input.
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All the GPS stuff in this thread is completely irrelevant to the OP, who sensibly has a separate receiver for his radio and, presumably, a Seatalk GPS for the plotter. His NMEA port is free and unencumbered and just needs the AIS wiring in to it. Which, as you and I and several others have found, works perfectly well.

His biggest problem is likely to be finding an NMEA cable for the plotter if he didn't keep the one that came with it :)

Pete
 
prv said:
All the GPS stuff in this thread is completely irrelevant to the OP, who sensibly has a separate receiver for his radio and, presumably, a Seatalk GPS for the plotter. His NMEA port is free and unencumbered and just needs the AIS wiring in to it. Which, as you and I and several others have found, works perfectly well.

His biggest problem is likely to be finding an NMEA cable for the plotter if he didn't keep the one that came with it :)

Pete
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I am afraid that NMEA cable did not come with the boat when I bought her. And I have indeed been told they are very hard to find.
So if anyone has one lying around for which they have no use, I'll be happy to buy it off them.
 
Finbar said:
This has been discussed before, see http://www.ybw.com/forums/showthread.php?443407-C120-NMEA-inputs-AIS-etc&highlight=c120+and+ais

As per that thread

Have done this with a Comar AIS. Basically feed the Raymarine Raystar 125 GPS NMEA into the Comar which multiplexes and sends AIS and position data to the C120 plotter, which is set to 38400 baud. As you know it only has one NMEA input.

I took a second connection from the output side of the Raystar 125 to the VHF which works fine.

The only downside is that the AIS needs to be on to get position data to the plotter. This means that anywhere near port I need to switch off my AIS alarm as other wise it sound continuously.

This set up does not need a stand alone multiplexer, which keeps things simple.

It works fine even in busy trafffic areas,
Click to expand...
Barry, very encouraging to read this.. What are the specifications of the Comar? Could it be that its data stream is lighter than that of the Raymarine AIS 650?
 
westhinder said:
What are the specifications of the Comar? Could it be that its data stream is lighter than that of the Raymarine AIS 650?
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The only way the data stream could be "lighter" is if it's failing to see some of the ships. Which isn't really what you want...

My AIS receiver is the one built into the GX2100 radio, with a top-quality antenna installation at the masthead (running the 11mm cable was a pain in the arse, but reception is dramatically better than with the thin stuff often used). So I receive over a very wide radius, and while I've never sailed in Belgium and seen the traffic there, Southampton, Portsmouth, the Solent and the central English Channel are not exactly a remote backwater. Yet my C70 doesn't grind to a halt from over-work.

It'll be fine.

Pete
 
whiteshythe said:
RichardS said:
But Steve is saying his GPS is Seatalk and he needs the multiplexer. :confused:

Yes, but only because I am feeding AIS AND Fast Heading info into the C120

Steve
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Ah .... I see now. I thought that fast heading info was just the heading data which comes from the GPS or the fluxgate which is usually Seatalk on a Raymarine system.

It appears that I don't know what fast heading info is! My autopilot and AIS systems must work well without it.

Richard
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It's a relatively old Comar SLR 200 that I picked up on fleabay. It has its own antenna mounted on the pushpit, which also doubles as an emergency VHF aerial - the adapter is stored near the VHF.
 
prv said:
More likely they get it by Seatalk, but not everybody's does.
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On Raymarine kit, fast heading data is sent by NMEA, at 10Hz. The rate gyro also needs SeaTalk connection, but that's for calibration. I fitted one to the C120 on my old boat, and it made a big difference to the stability of the radar overlay.
 
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