The proper lightning ground procedure for a carbon mast is to have a large internal copper wire, (like #2 MIN, or preferably #00). This would be connected at the top to a pointed rod or a pointed rod with bottle brush bristles as well. (Ion dissipater) It is supposed to be the "tallest thing", but the VHF
antennae always wins out on that count.
The other end of the wire should go as straight as possible to a copper plate, (NO sharp turns), mounted to the hull
. (2 sq ft min for salt water
, 4 sq ft min for fresh water) The accumulated liner inches of edge is most important, so a long rectangle is better than a square.
Do NOT use a Dynaplate... "Dynaplates" are useless unless soaked in acid at every haul out
, to remove clogging growth, AND they can be dangerous in a lightning strike. They have been known to explode. Regardless, they make a very poor lightning ground.
ALSO, grounding that rod rigging, (through the inner chainplate bolts), as well as large interior
metal, with a #6 green wire, is also a good idea, as it helps prevent "side flashes". IT DOES NOT REPLACE THE MAST'S COPPER WIRE. SS is a very poor conductor, only a SMALL fraction of the conductivity of copper. The only reason an aluminum
mast itself can be it's own lightning conductor, in spite of it's poor conductivity, is that it's size is hundreds of times that of a copper wire.
This "lightning grounding issue" is one of the downsides of a carbon mast, and eats up some of the lighter weight that you paid so dearly for. Nevertheless, it is wise for ALL of us to have a grounded mast. The likelihood of taking a hit in lightning prone areas, is in the neighborhood of 50/50 over the life of the boat. Proper grounding will not necessarily prevent all damage, especially to electronics
, but it will prevent holing the hull
, or driving the mast through the bottom!
The one given, is that IF lightning hits your mast, it WILL proceed to find "ground", through one path or the other!
Good luck as well!