24' Fiberglass OB powerboat. Dual batteries, one starting, one deep cycle accessories. All electrical and lightning (t-top) grounds connect to a dynaplate mounted to the underside of the boat. First, is that correct 12v grounding?
Second, my brass thru-hull and brass drain plug have deteriorated from apparent electrolysis. The boat is on a trailer mostly but stays in the water for a few weeks at a time during the summers in the keys. Is the grounding causing this electrolysis and what is the remedy? Would a hull zinc connected to the brass thru hulls solve this. And should they be connected to the dynaplate ground or isolated?