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From: Jeffrey Mills (no email)
Date: Mon May 14 2007 - 18:02:51 EDT
I'm trying to find my link to a video about lightning protection for
sailboats that I saw on the Net, created by a Florida professor who was an
avid sailor.
I believe he recommended 4-gauge copper wire, or thicker, be used. The path
should be as straight as possible of course. He also recommended that the
forestay and backstay, assuming they are steel, also are part of the scheme,
making a sort of Faraday cage. Most importantly, the underwater portion of
the conductor should be long-- at least 4 feet long I think-- to allow
dissipation of the lightning in the water, lest it take other, less
auspicious paths. He suggested a metal strip that ran along the keel line,
all the way to the other stay, sort of like a very long chain plate.
Also, the antennas should not only be disconnected from their equipment, but
the cable ends be pushed well away from them.
The most serious damage is when the lightning runs down the mast, and not
sufficiently grounded, it fans out, creating many pin holes through the
hull, and through you if you're in the way.
He also said something like the lightning doesn't even see your boat until
it has descended within 200 feet of you. So you have to be pretty down on
your luck to begin with.
Personally, I have a wooden mast, a wooden boat, and no metal stays, and no
metal really aloft at all except an antenna, and though I'm not invisible to
lightning, I feel I have greater dangers to worry about: things like
flotsam, poor seaamanship, and other people.
Hopefully I'll find that link here in a day or two.
Jeff
"Everett Ruess"
22-ft St.Pierre dory, lug-rigged cat/ketch auxiliary
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