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From: Norm of Bandersnatch (no email)
Date: Tue May 15 2007 - 08:24:34 EDT
Jeff,
Lightening may like to come down your antenna cable.
When the lightening researchers at Cape Canaveral in Florida send their
rockets up into a lightening-ripe cloud to entice a lightening bolt it
trails a very fine copper wire that unwinds out of the rocket as it rises
into the cloud. When the lightening does its thing the wire evaporates
instantly but the lightening bolt happens anyway.
So perhaps your antenna wire, however fine, may act in the same way.
Perhaps the disconnected antenna connectors should be plugged into shorted
receptacles to avoid arcing in the connectors.
When I was a teen-aged ham radio operator I had a long-wire antenna about
150' long. At the grounding knife switch I made a spark gap to ground.
The gap was about 1/8 to 1/16 inch between two pointed copper wires. It
would spark during some atmospheric conditions, including rainstorms, but
even when there was no lightening apparent. It would also arc in unison
with nearby lightening strikes.
Thank you for giving us the information from the video. It seems like wise
advice from an expert. I am looking forward the link to the video when you
find it.
Exactly what do you use for your non-metallic stays?
Norm
S/V Bandersnatch
Lying 30 07.715N 081 38.394W
Julington Creek Estuary FL
> [Original Message]
> From: Jeffrey Mills <>
> To: <>
> Date: 5/14/2007 6:51:50 PM
> Subject: lv-ab: Re: lightning protection for sailboats
>
> 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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