The DC system should be an isolated system on a boat, any stray voltages will rapidly increase corrosion of metalic parts. What you're describing is the grounding of the rigging & mast in case of a lightning strike. I should also add that its a good idea to isolate the shore power ground either with a ground isolator or better yet, an isolation transformer of suitable size for your system (voltage and wattage). Make sure you don't remove the ground (bad things can happen) but just isolateit. This might sound complicated or unnecessary but what you're trying to do is eliminate any electrical paths between your boat and any neighbours or piers. Marinas with supplied shore power are usually full of small underwater electrical currents, most of which can be rendered ineffective through proper grounding and the use of zinc anodes on exposed metalic surfaces.
Cheers
John
Just for information, the picture below is 'the old man in the sea' and not a self portrait as has been suggested by someone I know.
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