Assuming that your West Marine 580 VHF Radio will use NMEA 0183: you should use the wires from the GPS Receivers NMAE “pigtail” wire. This is the second, shorter, wire that comes out of the GPS Receiver’s plug. Depending on which GPS Receiver you have and when it was built you will have either the Red, White and Black wires or Green, White and Black colored wires under the black plastic end cap on the pigtail wire. Connect either the White or Green wire (NMEA+ Output) to the NMEA In on the 580 VHF and the Black wire (either version) to the NMEA Ground on the 580 VHF. Be sure to set the NMEA Output menu to “On”.