Raymarine C80 & AIS

[rwakeham]

Following lots of positive comments I have been thinking about adding AIS to my Raymarine C80. However, I am slightly confused about the cabling. I understand the AIS inputs to the C80 via the NMEA port configured for 38,400 baud.

According to http://www.raymarine.com/raymarine/Produ...product_id=2976 this means that I will not be able to use the Data out functions on the C80 NMEA port for the DSC radio or Autopilot.

I have a Raymarine ST60 Graphic display connected via Sea Talk ,which also has a NMEA out port - so rather than spend more money with Raymarine on their E85001 SeaTalk/PC/NMEA Interface Module can I just use this port ?

Also in this configuration does this mean that the AIS device (EasyAIS or NASA) still require a GPS NMEA input or is this functionality taken over by the C80 ?

Once again thanks for your help in advance...

 

[crisjones]

Re: Raymarine C80 & AIS

The solution will depend on what else you have installed. Do you have an auto pilot with course computer?

The easy solution is to use the EasyAIS because this can be configured to send the AIS data at 4800baud, this means that all your NMEA devices will still operate because 4800 is the standard speed. I suspect that the ST60 NMEA output will be at whatever speed the plotter is set to, although I am not sure on this point.

If your Autopilot is a Raymarine it probably operates on Seatalk rather than NMEA, however the DSC does need the position data on NMEA at 4800. If you have a Raymarine course computer you can use the NMEA (2) out terminals on the course computer for the radio, this will still be at 4800 regardless of the C80 setting.

The main problem with Raymarine C & E series plotters is getting the fast heading data required for MARPA (radar) to the unit along with the AIS data. This is normally the only NMEA data the C80 will need in addition to the AIS. The fast heading data is output by the course computer on NMEA (1) at 4800.

If you go for the EasyAIS then you can connect this NMEA (1) output to the EasyAIS and it will then send it to the C80 together with the AIS data. You can then choose to have the data at 4800 or 38400 simply by changing the settings on the EasyAIS and C80 to match each other.

I have an EasyAIS with E80 and Type400 course computer and this works fine, in effect the EasyAIS is a multiplexer for the fast heading NMEA data. I have not found any noticeable difference in the performance of the plotter and AIS whichever NMEA speed option you choose, although I have finally set mine to the faster speed.

DSC radio NMEA is from the course computer and everything works fine.

 

[ParaHandy]

i did, almost, exactly the same for the same reasoning: use the st60 graphics nmea-out rather than buy raymarines expensive sea talk-nmea converter.

I also used the nmea-in of the graphic to accept gps data from a garmin gps.

don't bother combining gps and ais data in the AIS box.

 

[Talulah]

General question: Is it worth waiting for the Raymarine AIS receiver now due sometime in June? The price quoted on one site is £650.

 

[rwakeham]

Most other units appear to be at least £400 less. I like the ease of use of raymarine, but the cost is stupid.

 

[tome]

Re: Raymarine C80 & AIS

You would find a big difference between the 2 peeds in any area of dense shipping (Solent, x-channel etc). 4800 baud simply isn't fast enough to handle the volume of AIS data, which is why the faster 38,400 baud was introduced

 

[pvb]

Raymarine AIS250...

[ QUOTE ]
Most other units appear to be at least £400 less. I like the ease of use of raymarine, but the cost is stupid.

[/ QUOTE ]Worth remembering that the AIS250 includes a multiplexer, an aerial splitter and a VHF/FM splitter. And you can be pretty certain it will just plug'n'play.

 

[fireball]

Re: Raymarine AIS250...

[ QUOTE ]
an aerial splitter

[/ QUOTE ]Hadn't we pretty much established that it is a better idea to have a second antenna for AIS as this then gives you an installed backup if you ever loose the primary one ....

 

[rwakeham]

Re: Raymarine AIS250...

I've just had the masts down and I have found I actually have 4 (!) VHF antennas - have not discovered what they all do and whether they all work yet.

 

[pvb]

Re: Raymarine AIS250...

[ QUOTE ]
Hadn't we pretty much established that it is a better idea to have a second antenna for AIS as this then gives you an installed backup if you ever loose the primary one ....

[/ QUOTE ]Did we? Obviously nobody told Raymarine! /forums/images/graemlins/wink.gif

 

[ParaHandy]

I have a notion, Tome may know better, but I think you have to get this box if you want Marpa. Marpa without a fast heading sensor is utterly useless and the sensor feeds data into the C series (or E series) at a different baud rate than AIS.

I'm not entirely convinced that a fast heading sensor will cure what I witnessed with an E series and that on a reasonably stable cat. It seemed so bad that even many orders of magnitude greater compass update rate might not cure its waywardness ... perhaps it does. I don't know.

 

[WayneS]

I have disconnected the NMEA feed from my course computer to add AIS and so rely on the 2hz SeaTalk heading updates.

To be totally honest, I have seen little change in the reliability of Marpa but have no previous experience to compare it with. When tracking a target on AIS and Marpa, CPA does differ but not by much.

At any rate, a Marpa CPA of less than a few miles make me take evasive action anyway, but that is just me being very cautious.

Cheers

Wayne

 

[hubert]

Using AIS with a 4800 baud transfer is not advisable. To send the shortest message (say message 1) at 4800 baud takes about 125mS. With vessels underway reporting at 2 second intervals,the absolute maximum number of vessels that 4800 baud can handle, without loss of data, is therefore only 16.
All other vessels, even if they happen to be on a collision course, are irretrievably lost.

 

[jwrhind]

Quote
"I have a Raymarine ST60 Graphic display connected via Sea Talk ,which also has a NMEA out port - so rather than spend more money with Raymarine on their E85001 SeaTalk/PC/NMEA Interface Module can I just use this port ?"
/

Sadly, I think you'll find that the ST60 Graphic does not output a NMEA GPS position sentence, so you cannot use the o/p of this to provide position to your DSC radio. At least that's what the manual suggests.