Re: [Paddlewise] Anyone understand lightning?

You're absolutely right, Mike. The mast on my Columbia was stepped on top 
of the cabin in an aluminum shoe. A heavy duty copper cable ran from the 
shoe bolts in the cabin down to the keel mounting hardware in the bilge. 
The keel was about 6 feet deep and 700 lbs of lead. A great ground. Also, I 
had a FM radio antenna on top of the mast that was electrically isolated 
from the rest of the boat so that lightning would go down the mast rather 
than the radio antenna or the shrouds. Highly effective system though I 
never saw it tested in the years I owned the boat.

I am aware of someone who died on a sailboat from a lightning strike in a 
Norfolk, Va marina. To make a long story short, his boat did not have a 
grounded mast. He died in his sleep when lightning struck the mast, 
traveled down a shroud and entered his body laying in a bunk up against the 
hardware that held a chainplate in place. One hand, where lightning exited 
his body, was very close to a 110 Volt outlet in his shore power system 
which was connected to the dock. A very freak accident that happened at the 
same time when I lived on my boat in Hampton, Va. Caused me to carefully 
check out my grounding system.

Coincidentally, I believe there are more injuries and deaths on sailboats 
from low hanging power lines than from lightning.
Dave G.

At 18:38 8/21/02, Michael Daly wrote:

>I think you misread or misunderstood his comment.  Masts are definitely
>grounded to the water - the usual path is throught the keel - sailboat
>keels are often lead.  If the mast is stepped on deck, they use a heavy
>wire to connect to the keel.  If stepped on the keel, they make sure
>there's a good electrical contact.  If it is not grounded to the keel,
>the current will find another path and can do a lot of damage.

<snip>

>Mike


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