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Lightning Strike?

Old 09-03-2012, 02:08 PM
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Default Lightning Strike?

We had a tremendous lighting storm In Bethany Beach last weekend, stayed over our house and marine for several hours...

Now the electronics on my boat won't come on -- Furuno Chartplotter/fishfinder and rader. The stereo, VHF and lighting are all fine. No signs of damage, no blown fuses and power is getting to the units. Could lightning have hit the boat or nearby and damaged them even if they were powered off?
Old 09-03-2012, 04:56 PM
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On July 4th, 2011 a boat in a lift 60 feet from our boat (in our slip) took a direct lightning hit.

We had boats with various levels of electronics damage within about a 100-ft radius.

In our case, the Electro-Magnetic Pulse (EMP) induced a voltage in the NMEA2K bus that fried numerous connected components.

We lost our Lowrance radar, one of two GPS receivers, the Simrad AP-16 electronics, and the segment of the engine ECMs that formats the Command Link output (connected to NMEA2K bus). About $7000 just for the material, and the insurance company let me do my own installations, based on the input from the surveyor they sent.

I would strongly recommend that you get this all checked out very carefully. Pumps and other things that you might not think to check could also be inoperative, e.g. fresh water, live well, trim tabs, etc.

Also, the insurance companies seem to accept that all damage may not be immediately apparent. We did not have any supplemental claim, but several folks with lifts had their drive motors fail within a month or so after the lightning strike.

Brian
Old 09-03-2012, 06:38 PM
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Originally Posted by Capt. Dan View Post
Could lightning have hit the boat or nearby and damaged them even if they were powered off?

Yes. Absolutely positively.
Old 09-03-2012, 09:13 PM
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+1 Yes. I've lost my tank level indicators, a VHF, WiFi repeater and charger on two occasions. The strikes were certainly close but not direct.
Old 09-04-2012, 06:05 AM
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Thanks all. What perplexes me is I can find no visible damage and I have no shorepower. So did it come through my out drive or outriggers?
Old 09-04-2012, 06:35 AM
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Originally Posted by Capt. Dan View Post
Thanks all. What perplexes me is I can find no visible damage and I have no shorepower. So did it come through my out drive or outriggers?
You may not see any physicial damage if you did not take the hit directly. I had a strike hit a tree 15 feet from my house last week and it took out the cable and the internet, as well as the router and tripped every GFI breaker at the main panel. With that many volts it does not have to be all that close (within 75 feet) to cause damage. Hope you get it all sorted out quickly.
Old 09-04-2012, 06:48 AM
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You don't have to have any connections to power at all. The magnetic field from the extreme currents within a lightning bolt creates it's own electricity in any conductor it encounters (ie: your boat wiring). This induced voltage can arc over the open contacts in switches and is what kills electronics nearby. It even induces damaging currents in the traces of printed wiring boards within the unit. The military uses this phenomenon as a weapon. See EMP in Wikipedia.
Old 09-04-2012, 08:27 AM
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Yes, You do not need a direct hit to do damage. I know it is not relevant but I have several antenna's that is not DC grounded that I keep unhooked unless in use. When a
cloud comes buy you can see the static discharge between the center conductor and shield, and a big pop. If connected at time of discharge a radio could go up in smoke. Lightning and associated static discharge can, and will destroy.

Charlie
Old 09-04-2012, 01:07 PM
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Lightning is a persistent force. It can jump circuit breakers easily, come in through the data buse and will also come in the back door thru the grounding system.
Old 09-09-2012, 06:55 PM
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Default Exit Wound

I mentioned in my post above that a boat in a lift near us took the direct hit.

It was a Grady-White 222 Fisherman. The VHF antenna was hit, the current passed down through the console, blowing out all the electronics and switch bodies. It ran aft through the stringers and exited on both sides of the boat, to the aft aluminum crossmember of the lift.

These show the VHF 'entry wound' and the port side 'exit wound'.
Attached Images   
Old 09-10-2012, 03:34 PM
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Lightening will frequently kill standing cows even though the strike was not really close enough to hit them. What happens is the charge starts to travel across the surface of the ground creating a potential difference as you get further away. The cows stand with hooves separated by a foot or two, and that is enough of a potential differential to stop their hearts.

The same thing can happen on water or across shore power circuits.
Old 09-10-2012, 04:00 PM
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Definitely... powered on or off is no difference. Having them physically disconnected by means of a switch can definitely help, but due to the voltage involved lightning can jump across anything if it feels like it.

Fantastic picture and thanks for sharing... glad nobody was hurt. A great example of how dangerous lightning is.
Old 09-10-2012, 11:09 PM
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Not unusual for no sign of entry, from what I've learned. First sign of something terribly wrong was the smoke coming out of the engine room from the Isoboost transformer.

Oddly enough that unit need only a circuit board and some other parts easily repaired. However mostly everything with a circuit board on the engines, generators, battery chargers, GPS's, and all sorts of other equipment was toasted. This was on a 65' Viking.

For what its worth, the Furuno Radar, bottom machine and Simrad AP all appear to be fully functional. Chartplotters lost their NEMA 0183 ports however, along with stereos, radios, satellite dome, etc.

We're well north of 100k in damage. Never found a point of entry. Insure well, and know your deductible, lightning damage to boats is very common. Also absolutely unpredictable.

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