Surface area doesn't really matter for a lightning ground, edge length does.
The charge will dissipate along the edges, so a long piece of copper foil
would do much better, maybe 2" wide standard stuff. Like Jim said, nothing
is foolproof, but you can always help your friend the lightning bolt out to
find his way to a home in the water! Bigger is better for cable, try to keep
any turns to a 12" or so radius, and you can probably do better than no
protection at all.

I have a similar system... lightning rod to cable that goes overboard at the
dock to a copper plate with lots of cuts in it (for more edge area) that
sits on the bottom. I can't prove that it ever worked, but one time I pulled
it up and the plate was gone. The cable looked like it had been cut clean
off and was dark. I know it didn't pull out of the connector since there was
no exposed wire. Either it did it's job while I was gone, or somebody on my
dock needed a crappy looking piece of copper sheet!

--


Keith
__
"Tom."
-Tom Nissalke, New coach of the NBA's Houston Rockets, when
asked how he pronounced his name, 1966.
"Parallax" wrote in message
om...
Thunderstorms every day and my fear of lightning (totally justified)
have caused me to once again scheme up a way to protect my sailboat.
For protection while anchored, I have a 2'X2' copper sheet with very
thick stranded tinned cable with a clamp for attachment to the mast.
I have considered using this while underway but it would cause too
much drag and would probably foul the prop.

So........another useless idea. How could you tow a lightning ground?
Such a ground doesnt have to be a sheet. it just has to have large
surface area. Could attach it to the bottom of the dinghy and tow it
with proper cable going to the mast but I try not to tow my dinghy.
OK, why not something like a boogie board (foam) covered with Cu foil.
No matter which side it had in the water, it would have lots of area
submerged. It would produce minimal drag. Any thoughts?

Designing a Lightning protection scheme without a proper study
you are likely to attract all the sky sparks right to your boat, while
the other guy a 100 yards away will get nothing.
If you do it, do it the classic way: Thick rod, thick cable, very good
ground (into the sea) no turns, no tricks, no shortcuts, no revolutionary
ideas. Otherwise don't.
That's what an aerospace engineer told me.
Given in good faith and without guarantee!!!
Good luck




"Keith" wrote in message
...
Surface area doesn't really matter for a lightning ground, edge length
does.
The charge will dissipate along the edges, so a long piece of copper foil
would do much better, maybe 2" wide standard stuff. Like Jim said, nothing
is foolproof, but you can always help your friend the lightning bolt out
to
find his way to a home in the water! Bigger is better for cable, try to
keep
any turns to a 12" or so radius, and you can probably do better than no
protection at all.

I have a similar system... lightning rod to cable that goes overboard at
the
dock to a copper plate with lots of cuts in it (for more edge area) that
sits on the bottom. I can't prove that it ever worked, but one time I
pulled
it up and the plate was gone. The cable looked like it had been cut clean
off and was dark. I know it didn't pull out of the connector since there
was
no exposed wire. Either it did it's job while I was gone, or somebody on
my
dock needed a crappy looking piece of copper sheet!

--


Keith
__
"Tom."
-Tom Nissalke, New coach of the NBA's Houston Rockets, when
asked how he pronounced his name, 1966.
"Parallax" wrote in message
om...
Thunderstorms every day and my fear of lightning (totally justified)
have caused me to once again scheme up a way to protect my sailboat.
For protection while anchored, I have a 2'X2' copper sheet with very
thick stranded tinned cable with a clamp for attachment to the mast.
I have considered using this while underway but it would cause too
much drag and would probably foul the prop.

So........another useless idea. How could you tow a lightning ground?
Such a ground doesnt have to be a sheet. it just has to have large
surface area. Could attach it to the bottom of the dinghy and tow it
with proper cable going to the mast but I try not to tow my dinghy.
OK, why not something like a boogie board (foam) covered with Cu foil.
No matter which side it had in the water, it would have lots of area
submerged. It would produce minimal drag. Any thoughts?

How about connecting a 20 ft piece of #1 cable to the backstay and
dragging that around.


On Tue, 6 Jul 2004 06:07:38 -0500, "Keith"
wrote:

Surface area doesn't really matter for a lightning ground, edge length does.
The charge will dissipate along the edges, so a long piece of copper foil
would do much better, maybe 2" wide standard stuff. Like Jim said, nothing
is foolproof, but you can always help your friend the lightning bolt out to
find his way to a home in the water! Bigger is better for cable, try to keep
any turns to a 12" or so radius, and you can probably do better than no
protection at all.

I have a similar system... lightning rod to cable that goes overboard at the
dock to a copper plate with lots of cuts in it (for more edge area) that
sits on the bottom. I can't prove that it ever worked, but one time I pulled
it up and the plate was gone. The cable looked like it had been cut clean
off and was dark. I know it didn't pull out of the connector since there was
no exposed wire. Either it did it's job while I was gone, or somebody on my
dock needed a crappy looking piece of copper sheet!