Hey, SeaSlug sorry to hear the fish finder is not working. Perry is right about the corrosion on the cables and connections. Salt water can do a number on that stuff in no time at all. If that turns out to be the problem try switching your connections to two post water proof trailer plugs for the power connections. I have the plug soldered directly to the terminals on a 12 volt 7 amp hour battery. Then give the connections a good coating of some marine grade silicone to seal them. Do the same thing with any splice connections in the circuit. This is how we used to keep our comunications and underwater electronics working in my offshore days. This will save you the worry if your system takes a dunk in the future. Hope this helps a little.
