Raymarine A06068 Seatalk Ng 9M Backbone Cable. In a SeaTalkng installation, a backbone cable runs through the length of the boat.Individual devices connect to the backbone by spur cables that run to T-pieces on the backbone. The backbone carries both data and power to attached devices. The backbone should be sized so that it will run past every location where an NG or NMEA 2000 device might be installed.