C70 Displays and MARPA

[robbieg]

Just fitted a C70 radar system. The unit has AIS, Fast Heading Data from a gyro autopilot and SOG from a GPS. It doesn't have speed through the water.

The Marpa seems to work ok with targets doing a decent speed (which is good!) and agrees pretty much with the AIS data. However, slow traffic or stationary (eg buoys) produce some strange readings-bouys doing 5 knts etc. Woud speed through the water data help with these calcs ?

TIA.

 

[sailorman]

unless you have a Gyro fitted forget it in all but calm conditions.
yachts "Yaw" too much

 

[Marsupial]

I have a C70 radar and have thrown quite a lot of money at it to make it perform and IMHO the MARPA is a waste of time, I have seen it report the Dover Calais ferry doing 70Kts! and Buoys doing 25! I have lots of other issues with the C70, like the head up display ISNT head up and the DATA boxes dont have transparent backgrounds - so you lose the plot if you see what I mean. But as a basic radar to see whats out there its OK.

 

[Talulah]

Don't forget that for the fast heading output info the C70 must be connected to port 1 of NMEA outputs.

Just to be a bit clearer:
Make sure the NMEA (Port 1) of the autopilot is connected to the AIS unit (assuming Raymarine AIS) and the output of the AIS unit is connected to the NMEA input of the C70.

 

[DipperToo]

Also, how is the AIS data and Fast Heading data input to the C70? I have a C80 and used the EasyAIS which multiplexes the fast heading data from the course computer with the AIS data and inputs this into the C80 (remember to set the C80 input speed up to 38,400 baud. Yes. sometimes buoys do seem to move!

 

[robbieg]

The NMEA input is via a muliplexer-takes 4800 baud from the GPS and smart heading gyro and 38000 baud from the Comar AIS and outputs it as a 38000 baud stream to the C70's input port. The C70 is set to 38000 baud and takes all the data ok. Still get bouys doing 5 knots though!