On my 1981 Ocean Yachts I have a dual grounding tube about 12 feet long running outside at the turn of the keel which has been painted over the many years. Is the many layers of paint causing me a bad ground ? Should it not be painted? Also the inside of the tubes is filled with sea growth . Perhaps clean that out with a long piece of all-thread-rod? If not, can I just sand it clean in various spots to get a good ground? I have one grounding stud coming up through the hull in the engine room from it for sure. Since it's so long , I would assume there are other studs coming through the hull ? I haven't found any, but really haven't looked that hard either.