Just got a 'pre-owned' VHF where the 12 volt supply lead is Blue+Black can someone please confirm the +/- orientation. Would hate to get it stern about bow
convention would be black = -ve. If you have a multi tester check the resitance between each wire and the metal case of the unit, there should be 0Ohm between the -ve wire and the case.
Quite a few years ago I installed German electrical equipment and the wiring convention was always Black Positive. Can,t be sure that the negative was blue (but could have been) - so don,t do anything until your sure.
For single phase A.C. on ships that were built in Germany, the wiring was Black, White and Red - the Red being the earth!!!! I can't quite remember what the 3 phase colours were - but not Red, Yellow, Blue. I am almost sure they were Red, White, Black, with the earth being the armoured screen. The DC system was Black ve, and White -ve.
The systems were installed by AEG and were "interesting".