Does it work fine with the raymarine C70?

Yes, normally no problem. But you have to check whether the C70 is already AIS capable.If you find an “AIS topic” in the systems configuration if it is AIS capable. If there is no “AIS settings” you probably have to make a plotter software update first. For that please contact your Raymarine dealer. Also please check, whether the NMEA port is “free”. If this port is occupied with another unit and a different data speed in comparison to the easyTRX (easyTRX has got 38400 Baud data rate), than you might need a multiplexer to get the data with different speed into one NMEA port.