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capn_dave 08-16-2009 07:31 AM

Lightning Strike WOW!!!
 
While I have seen the aftermath of boats being hit by lightning, I have never actually witnessed one first hand until Friday.
In over 25 years I have lived in Florida I have seen some pretty good thunderstorms. This Friday I saw the mother of all lightning storms. The storm rolled in about 3:30 pm, I was watching it on the radar in the office and talking to a boat on the vhf. The lightning started and was all around the marina. There was a close strike about every 30 seconds. I watched the main pier get hit, the south mooring field take at least 2 hits. The shipyard just south of us took a couple. This was going on for what seemed like an hour, but was actually about 20 minutes. When BAM!!! A bolt of lightning hit a ketch about 150 yards away form my office. It looked like someone was welding on top of the mast. Sparks were flying down over the boat, making the mast look like a giant Fourth of July sparkler. I could hear a buzzing, crackling sound during the strike.
I knew a lady and young son were aboard, and tried to call them on her cell phone, as the storm wasn't even close to letting up. No answer.
I started shutting down the computers in the office, and praying, when my cell phone started ringing. It was the lady, she and her son were OK. Thank God.
She said her hair was standing up and sort of tingly right before the strike. She went on to say that it was like a machine gun going off inside the boat. Every light bulb exploded and threw glass all over the cabin.

Yesterday we checked the boat and found what was left of the VHF antenna. It seemed all the thru- hulls were OK, but all the electronics were fried, all the appliances that were plugged in were fried. The most important thing was nobody was hurt. Just needed a trip to the laundromat to wash their underwear.
The owner had bonded the boat just last year, grounding plates the works.
Does bonding work? Still can't say. Lightning is gonna do what it's gonna do.

Fair Winds
Dave:o :confused:

scottyt 08-16-2009 11:07 AM

as i tell people when i put surge protectors in houses... if a lightning bolt has a 100 million volts and the surge protector diverts 99.9 % of it you still have a 100 thousand volts going thru the house

captbillc 08-16-2009 12:45 PM

wow! that is quite a story , capn dave. i believe steel boats are safer. when we boarded my friend's 40 ft steel ketch a number of years ago we found the vhf antenna on the deck. it had been hit by lightning, but the radio & everything else was OK ! perhaps the strike had a lot lower voltage.

billyruffn 08-16-2009 01:32 PM

Quote:

Originally Posted by captbillc (Post 514098)
wow! that is quite a story , capn dave. i believe steel boats are safer. when we boarded my friend's 40 ft steel ketch a number of years ago we found the vhf antenna on the deck. it had been hit by lightning, but the radio & everything else was OK ! perhaps the strike had a lot lower voltage.

I've wondered if a steel boat (assuming it has both steel hull and deck) isn't like a faraday cage....

Quote:

From What is Faraday cage? - Definition from Whatis.com

A Faraday cage is a metallic enclosure that prevents the entry or escape of an electromagnetic field (EM field). An ideal Faraday cage consists of an unbroken, perfectly conducting shell. This ideal cannot be achieved in practice, but can be approached by using fine-mesh copper screening. For best performance, the cage should be directly connected to an earth ground.

A heavy-duty Faraday cage can protect against direct lightning strikes. When properly connected to an earth ground, the cage conducts the high current harmlessly to ground, and keeps the EM pulse from affecting personnel or hardware inside.
....my guess (and it's obviously only a guess) is a strike at the top of my mast would run to the deck and then either down the box beam that supports the mast to the keel, or around the deck plate to the hull plates to the keel.

Anyone know how it works with steel vessels?

St Anna 08-16-2009 02:59 PM

As far a as I know, its like billy says.

Lightning works its own way - so each strike or near miss will damage in a different way. Cant experiment with it to find out.

Steel boats will act like a faaday cage, but an antenna will bring the current down into the inside. I heard to disconnect the antenna if in a storm ** defeats the purpose doesnt it!!)

Us sailboats do have an aluminium (or sometimes wooden) lightning rod pointing up.

zeehag 08-16-2009 05:42 PM

iwholeheartedly and firmly believe in th epotential anti zap kat hat----as kats have never been known to be hit by lightning, and that the longest lightning rod is spozedly spozed to get the jolt first, i figger i have a kat on board--he has 9 lives left to go--plus the 9 left for the hat after his demise---sooooooooooooooo------the only answer to why wed didnt get hit by lightning when we were out trying to get into apalachicola during a bunch of big bad lightning storms, thru which we ended up sailing for 2 -3 days--gawd only knows why we didnt take a hit--i figger it must have been because there was a kat on board and there are no recorded events of lightning striking any kats----lol---makes no sense but makes as much sense as anything else regarding lightning----i hid UNDER the kat for the duration of the time i was not at helm----woohooo--we made it ....miracle!!!!

philsboat 08-16-2009 06:17 PM

We were standing on a dock near the 1000 Islands bridge when a lightning bolt hit a tree 200ft. away.The bolt looked to be 18" wide and pure white in broad daylight.We all ran for the steel boat that was at the dock and stayed inside till it passed.
If lightning hits a steel container (boat or a car) it should pass harmlessly around the occupants and should be a safe place to shelter,in a storm.
That's my theory for what it's worth.Anyway you look at it it's scary to be close to a big strike!!!
I was on a friend's sailboat during an electrical storm when we heard a buzzing in the backstay.Needless to say we left quite quickly,but nothing happened.
Another boat that was stuck near Belleville,On. didn't sink till two days after.It was full of pinholes.
That's my lightning stories for now.

Phil

zeehag 08-16-2009 06:55 PM

i was sleeping in lost angeles harbor in 1991 and i was on a power boat---a lightning bolt came down across the channel from me at 0308-i had awakened at 0300-i saw the scatter under it as it touched the asphalt---my ex hubby and my cat were asleep together sorta next to me--cat weighed about 20 pounds--was on his stomach---curled up=---the thunder made cat jump--he did so without waking---landed back on hubbies tummy without awakening either of them--i cracked up laffing---that woke cat and he made man awaken--neither knew what happened--was soooo funny....

jerryrlitton 08-17-2009 03:14 AM

One of our BlackHawk helicopters took a hit while on the ground. The tail rotor looked like a broom when it was said and done. All the avionics were of course fried. Took a hit while airborne once, all it did was two burn marks where it entered and exited.

bubb2 08-17-2009 08:37 AM

Quote:

Originally Posted by capn_dave (Post 514039)
She said her hair was standing up and sort of tingly right before the strike.

Every first hand lighting strike I have read about says the same thing. Much like what was said above, they felt the "charge" before the strike. If you are feeling that tingly feeling that is the time not to be touching anything that can be conductive.


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