Thanks for that answer Meindert. It is as I suspected, and I am
somewhat annoyed that the RayMarine gadgetry doesn't automatically talk

NMEA. to other components. I thought the entire reason for NMEA
standard is to have different brand components communicating.
Raymarine has ignored that.

My Garmin has wiring that says "DSC". Can I assume that it will work
just by wiring it into my ICom VHF?

This stuff is fascinating, but it doesn't seem like there's much
information available about it. Do you know of any books on this
subject?

thanks

Luc