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post #9 of Old 08-02-2004
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Lightening strike

Here''s what I have wittnessed over the years in Florida...from 10 yrs liveaboard/cruise and 45+ yrs on the water.

Bonded or not, grounded or not, a feeder strike can or will jump around to metal and electrical components. It jumps by people sitting below and connects with metal. It hits unbonded thru hulls, etc the same as bonded ones. The difference is in the strength of the lightning bolt whether it jumps or follows a path. No wire or system is capable of carrying the charge from a large feeder or main bolt strike. It is impossible. Just the pressure and heat from a main bolt will blow
apart or melt the boat.

A lessor strike (feeder) can burn perfectly symetrical holes through glass hulls where bolts penetrate. They look like a drill made the hole. It melts aluminum masts, sails and gear. It finds dry areas in the lamination and blows the glass apart (appeared to me it superheated the air pockets). I examined a Cal 25 that had a 3''x 4'' section of the hull lamination blown off...popped about 50% of the lamination off and left the other half. The keel bolts stretched 6-8" and the keel lowered. Two people dead and the boat sunk.

On the otherhand I saw a boat completely comsumed by "St Elmos Fire" and nothing happened. The whole boat glowed from stem to stern but nothing damaged.

Put a hand held miliampmeter on an aluminum mast. Every time the wind gusts you will see voltage. Small, but this static charge is what attracts strikes. Make a path big enough for the charge to bleed quickly and it will reduce strikes. I think rain water running off the boat helps bleed the charge in a big way.

Also, two weeks ago a long time friend of mine lost his wife to lightning. It blew her in half while she was holding their son in her arms to keep him warm. He is in critical condition.
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