Hi there, So I find this thread very interesting as Mistoffelees, our Nonsuch 33, got hit by a bolt of lightning several years ago here in the Cayman Islands. The bold separated into three strikes instantaneously. One strand hit the house and smashed roof tiles, one strand hit a very large tree, 3 or 4 feet thick, and set it completely on fire in pouring rain and the third bolt hit the mast! The damage to the boat was mainly to the electronics. It appears the VHF antenna wiring brought the current to the switch panel. Every little red LED (maybe it wasn’t LED back then) had popped the little red covers off and all the bulbs were blown or exploded. The VHF was toast, as were most of the electronics, the voltmeter for batteries had blown out of the panel, there were scorch marks everywhere. But only at the panel. The surveyor inspected the boat and no obvious damage elsewhere. I ascended the mast to discover the top plate had melted and welded to the mast – molten, re-cooled and now distorted, but still attached 10 years later. The VHF mounting, wind vane and masthead light were gone and just represented by different colours of molten metal. Nothing plastic was even visible – not even a stain.
The surveyor inspected the boat and we didn’t have a through hull issue, apparently marlon is good in that regard. What he did say was that it was fortunate we had a lightening cable grounded to the keel! He claimed that the large copper cable that exits the bottom of the mast and runs to the bilge was just that. It’s still there today attached to the first keel bolt. He suggested we change it now that the lightning strike had made it brittle and cooked it. We haven’t.
I guess my question is that I always thought we had a lightning protection ground in that cable and that it ran from the top of the mast. Is Mistoffelees the only Nonsuch with this set up or have I been misled to think that thick cable is in fact not a lightning conductor but something else? Maybe a simple ground attached somewhere else.
Very interested to know.
Tim
Mistoffelees
Nonsuch 33 #32
Cayman Islands