the hard way I rewired to use tinned copper and also tinned the ends of the wire when I cut it (all you need to do is solder the wire ends). The recommended water
proof connectors work
well. I add some conductive grease to the connection and shrink wrap it as well......... In one case I ran the connectors in a small section of PVC pipe. You put the conductor through an end cap, then put on the connector, (leave extra wire) make the connection, in the PVC pipe and put the cap on with Teflon tape to get a water tight seal. I used hot glue to seal the wire to the pipe caps. That ended my corrosion
issues in the bilge. Maybe a bit over the top, but it worked for me.