Yes your absolutely correct about the fishing boats. The marina also has many derelict boats and live-aboards on vessels well past their prime. I will pursue the galvanic isolator. I wan't sure about the grease coming out of the bottom of the gearbox, but I'm one to investigate until my confidence builds. it turns out there were "dry" pockets within the gearbox, and the upper bearings had significant rust and no longer turned smoothly.
