How to wire Raymarine Pro 7 Fish Finder

[DaveH]

I was given a Raymarine Pro 7 Fish finder as a birthday gift.
I'm not interested (at the moment) in using the Fish Finder but do want to use the GPS and Nav Maps.
I made a little wiring harness to use the power and neutral going to the Aux socket (cigarette lighter) but I'm not sure where I can connect the ground wire.
Anyone have any suggestions?
Thx,
Dave

 

[zipper]

All dc circuits are color coded per ABYC and USCG. Look for the appropiate colors for pos. and neg., In the chart, to use. It depends on current draw and length of run. Or install a pos/neg fuse block under helm and wire home runs to battery with a breaker at bat.