The yeoman is 12 volt, but as long as you use 12 volt to power it, it doesnt matter about the other instuments in the net, NMEA output is ok from either voltage. But I would check with yeoman!
Steady on Bargee, the chap may not have a clue what you mean!.....dave_roy_boy you are said to be SHOUTING when typing in capital letters - it is considered rude on most forums!