I am not an expert and the following advice is subject to correction by them what IS!!!
The original set-up was for the mast to be solidly grounded to a keel bolt by a heavy cable. This is for lightning protection and static electricity grounding.
Many years ago, we found a few boats which were home based near major military installations and discovered that they were losing their zincs at a rather rapid rate, whether docked or on a mooring. This problem appeared to exist only with two or three Nonsuches and not with adjacent boats which should be experiencing the same outside conditions. Our investigation seemed to suggest that the tall mast with no ground plane (e.g.: spreaders through which the current would be dissipated) was acting as a giant antenna and transferring the strong military radio waves in the area down through this ground. This is, as I understand it, an almost constant low-level flow of electricity through the ground.
At first, the suggestion was to simply cut the cable to interrupt the flow. Then other experts were afraid that we would lose the lightening ground protection. So ……….. the recommendation was to
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cut a 6- inch piece out of the middle of the cable
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insulate the ends with good rubber tape and
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crimp a piece of copper pipe over both ends. (So that it did not actually contact the metal cable.)
This way, the constant low-level flow of electricity would be eliminated, but a lightning strike would be conducted through the pipe.
I know this may sound fantastic, but it seemed to work!!! (I don’t think we ever proved that the lightning protection still worked, but the degradation of the zincs appeared to be eliminated.)
Allen Ames