Not sure that Gary is right about needing the converter box. It would appear that the Multi is supposed to generate NMEA data from the seatalk bus. But he is correct that - no data on the seatalk bus - no data on the NMEA output. So, unless you have a second instrument (Depth, Speed, etc.) hooked up with the Multi you will not see any output (which should happen every two seconds) on the NMEA bus. BTW - depending upon what other
Raymarine instrumentation you have you may find another NMEA to Seatalk converter - e.g. many of the
Raymarine autopilot computers have such a capability