RM C80 power connection

[Sailorman Ed]

I acquired a RM C80 chart plotter but wo the power cable. Can someone tell me which is negative and positive and what is the third terminal:

[GordMay]

[Sailorman Ed]

Thank you Gord, just what I needed. Does the shield wire also go to negative?

[GordMay]

The purpose of the shield is to conduct any of the noise it has picked up to ground. The cable shielding, and its termination must provide a low-impedance path to ground. A shielded cable that is not grounded does not work effectively.

[Sailorman Ed]

Thank you Gord, as always a wealth of good information !!!