Marty wrote:

Capt. JG wrote:

22:02 LIGHTENING PROTECTION SYSTEM: The lightening protection
system provides a "cone" of protection around the boat in the even of
a lightening storm. Grounding wires of #8 gauge copper connect all
chain plates and the mast step to the keel.



#8? Ha, Jon, I've seen the inside of an underground vault with the
walls spattered with copper after a 75KA short vaporized copper bus bars
1/2'" thick by 4" wide. That's one hell of lot of #8 wires in parallel.
Imagine what happens with surge that may exceed 200KA?

I go along with others that have suggested that lightning protection for
a plastic boat is probably an exercise in futility.

Cheers
Martin

#8 is obsolete. #4 grounding wires are now called for. Also I'd lay
odds that the 75KA short lasted for several cycles of your 60Hz mains
before the breakers cleared it. It almost certainly had more than 1000
times the energy that a 100KA 1us lightning strike would dissipate in a
single #8 cable.

If the protection system can prevent serious structural damage from 9
strikes out of 10 its obviously worth doing. If it reduces damage 50%
of the time so you dont have to abandon ship in the middle of a storm
its still worth doing if the cost is comparable to that of a liferaft.