When anchored during thunderstorms, I have a 2'X 2' piece of copper
sheet attached to OO guage stranded tinned ground braid that I attach
to my shrouds. However, this cannot be used underway because it would
trail in the water. I do not want to attach the sheet directly to the
hull because of my fears of 10E12 watts being disspiated against my
hull in 50 microseconds.
However, why not wrap the sheet around the rudder and use the ground
braid to attach it to the backstay? This would give plenty of surface
area and keep it away from the hull. A strike might disable my rudder
but I have a backup rudder I could use.

On 25 Mar 2004 11:28:18 -0800, (Parallax)
wrote:

When anchored during thunderstorms, I have a 2'X 2' piece of copper
sheet attached to OO guage stranded tinned ground braid that I attach
to my shrouds. However, this cannot be used underway because it would
trail in the water. I do not want to attach the sheet directly to the
hull because of my fears of 10E12 watts being disspiated against my
hull in 50 microseconds.
However, why not wrap the sheet around the rudder and use the ground
braid to attach it to the backstay? This would give plenty of surface
area and keep it away from the hull. A strike might disable my rudder
but I have a backup rudder I could use.
Having been stuck by lightning while underway I've found the best
prevention method is prayer. :-) Prior to being struck I hadn't
thought of this. Now I do it every time I see the thunder clouds. I
have yet to see a definitive article or paper on the best way to
protect a boat. Mine was a wing keel (keel stepped mast and I feel
the large surface area helped to dissipate the charge, keeping the
damage down to all the electronics,alternator, masthead array, mast
wiring,lights and a burnt headsail. No holes. My thru hulls weren't
bonded but there were burn marks in the bottom paint (treeing) at all
the thru hulls and at the gudgeon at the rudder. I have been told
that the jumper cable to the shrouds method doesn't work that well
because the charge travels faster thru the aluminum (mast) rather than
stainless (shrouds). If it makes you feel better go with it!

Rick Itenson
La Belle Aurore
Toronto

I like the idea, but what happens to the helmsman?
Greg.

"Parallax" wrote in message
om...
When anchored during thunderstorms, I have a 2'X 2' piece of copper
sheet attached to OO guage stranded tinned ground braid that I attach
to my shrouds. However, this cannot be used underway because it would
trail in the water. I do not want to attach the sheet directly to the
hull because of my fears of 10E12 watts being disspiated against my
hull in 50 microseconds.
However, why not wrap the sheet around the rudder and use the ground
braid to attach it to the backstay? This would give plenty of surface
area and keep it away from the hull. A strike might disable my rudder
but I have a backup rudder I could use.




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The rudder, on most boats, would be too far from the mast. You want to shunt
the lightening strike directly to ground (water). If your ground cable or
wire makes any bends/turns of less than ~6" radius, it will jump to
something else. Also if your ground strap runs parallel to other wiring or
life lines, it will arch or jump across.

There is no problem having a copper plate attached to your hull. The
lightning discharges though the edges of the plate, not the surface.
Therefore, you should not fair in the edges or file them down smooth. Leave
them sharp.. There is a formula for computing the linear measurement of the
plate edge perimeter. I found most of my information in the ABYC rules.

Steve
s/v Good Intentions

In article ,
(Parallax) wrote:

When anchored during thunderstorms, I have a 2'X 2' piece of copper
sheet attached to OO guage stranded tinned ground braid that I attach
to my shrouds. However, this cannot be used underway because it would
trail in the water. I do not want to attach the sheet directly to the
hull because of my fears of 10E12 watts being disspiated against my
hull in 50 microseconds.
However, why not wrap the sheet around the rudder and use the ground
braid to attach it to the backstay? This would give plenty of surface
area and keep it away from the hull. A strike might disable my rudder
but I have a backup rudder I could use.

I'm not sure I want to lose a rudder, even if the lightning didn't fry
me as it came past. ;-) Attaching a straight run from the mast to keel
is a usual first step. The plates are suspenders.

If a thunderstorm comes up, I'd stop, strike the sails, put the plate(s)
overboard, and go below.

--
Jere Lull
Xan-a-Deux ('73 Tanzer 28 #4 out of Tolchester, MD)
Xan's Pages: http://members.dca.net/jerelull/X-Main.html
Our BVI FAQs (290+ pics) http://homepage.mac.com/jerelull/BVI/

Jere Lull wrote in message ...
In article ,
(Parallax) wrote:

When anchored during thunderstorms, I have a 2'X 2' piece of copper
sheet attached to OO guage stranded tinned ground braid that I attach
to my shrouds. However, this cannot be used underway because it would
trail in the water. I do not want to attach the sheet directly to the
hull because of my fears of 10E12 watts being disspiated against my
hull in 50 microseconds.
However, why not wrap the sheet around the rudder and use the ground
braid to attach it to the backstay? This would give plenty of surface
area and keep it away from the hull. A strike might disable my rudder
but I have a backup rudder I could use.

I'm not sure I want to lose a rudder, even if the lightning didn't fry
me as it came past. ;-) Attaching a straight run from the mast to keel
is a usual first step. The plates are suspenders.

If a thunderstorm comes up, I'd stop, strike the sails, put the plate(s)
overboard, and go below.

I hear reccomendations that ppl stay inside for 20 minutes after they
hear the last thunder. If we did that, we would never go outside in
the summer herre in N. FL.