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Old 20-12-2011, 07:33   #16
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Re: Lightning strikes, any real experience?

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Originally Posted by Lagoon4us View Post
That's interesting regarding the three handhelds wrapped in foil i guess the intention was to create a faraday cage by doing that?
Only one hand held, a Magellan, was in the tinfoil/Ziplock/w/ silica. An old timer once told me he wrapped his sensitive electronics in tinfoil and it saved his equipment during a lightning strike. I knew he had been hit so figured he was right.

Seeing as I never really used this GPS, it was there only for ditching, I ripped off some aluminum foil and stuck it the Ziplock with a silica packet and tossed it in the waterproof ditch box with some Lithium batteries..

I figured aluminum foil prevented noise and acted as a shield on coax wire so why not give it a try, it's cheap.... Well, it did not work, and I soon after discovered that you need real steel to create a Farday cage that will work..


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Originally Posted by CoasterNZ View Post
Wonder if a good faraday cage can be made to prevent damage, my only experience is using perforated steel? Any thoughts???
It claims to work but after reading about how to properly construct one I just bought a US military ammo box instead. That probably won't work either but then again not much will in a lightning strike.

When I spoke with engineers at Raymarine, Garmin and other companies such as Standard Horizon none of them were surprised about these non-plugged-in failures.. They claim the electronics in these devices are so sensitive that even static electricity can damage them. This is why the repair technicians wear earthing straps when working on sensitive electronics. A large magnetic pulse from lightning, I would guess, based on my outcome, is a lot worse than a little static electricity...
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Old 20-12-2011, 07:43   #17
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Re: Lightning strikes, any real experience?

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A discussion has come up regarding lightening strikes and their effect to respective yachts, can any contributors evaluate their actual experience/knowledge of a direct hit, near miss?

Just how unservicable did systems become? Regarding Rig and rigging, hard wiring, electronics etc

What earthing can be done that can help minimise damage?
I have gone into the subject EXTENSIVELY in past posts, with decades of intense research, boatbuilding / repair, and liveaboard / cruising as a reference. You may look up the information in my past posts... I found the process of explaining this subject to others, frustrating enough, that I prefer not to repeat the experience.

Best regards,
Mark
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Old 20-12-2011, 12:36   #18
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Re: Lightning strikes, any real experience?

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I have gone into the subject EXTENSIVELY in past posts, with decades of intense research, boatbuilding / repair, and liveaboard / cruising as a reference. You may look up the information in my past posts... I found the process of explaining this subject to others, frustrating enough, that I prefer not to repeat the experience.

Best regards,
Mark
Thanks for that i understand the frustration. Cheers
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Old 20-12-2011, 13:54   #19
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Re: Lightning strikes, any real experience?

I got struck ( or possibly a very near strike rather than a direct hit) a couple of years ago while at anchor. Its an aluminium boat so its automatically well grounded and is a reasonable faraday cage inside.
The only damage to electronics was anything outside or anything that was on at the time. All equipment that off and down below suffered no damage. I have not had any subsequent failures.
I read quite a bit about lightening just after the strike and the conclusions I reached was that grounding greatly decreased the damage and slightly reduced, or made no difference, to the chance of a strike.
Lightening strikes are extremely variable and nothing will prevent major damage from a severe strike, but I think grounding the boat and turning off equipment does help reduce the damage and there seems no basis for the belief, expressed here, that grounding increases the risk of a strike.
Pantaenius insurance was very good at replacing the equipment.
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Old 20-12-2011, 14:56   #20
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Re: Lightning strikes, any real experience?

I have everything on quick disconnects, for power and any other connection. I have a heavy copper cable from top of mast to grounding plate throughhull midships, I don’t want it wandering aft if I can help it. I have not been hit but lighting is so rare in the PNW I know most boats don’t do anything to prepare for it.

I understand stuff that fries even through not plugged in is hit and miss, it is an EMP pulse that is thrown off that does it, I hope to never find out.
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Old 20-12-2011, 15:20   #21
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Re: Lightning strikes, any real experience?

We were hit
And we had a yacht with a considerably higher mast about 150ft from us at the time
We had motor in water and that's where the charge went out, down aerial, through VHF and then through wiring and out motor.

Killed off all electronics (log head actually exploded out of cockpit bulkhead and hit me) , left cheap "Lucky" brand fluoros intact, basically anything worth more than $20 that was wired in was dead (hand held GPS turned off in nav table was OK), blew coved on pvc halves (wiring conduit) off of walls, melted some wiring, melted rubber bush in outboard prop, so no drive.

Rigging wire appeared to be OK allowing us to sail home under reduced sail, but was replaced under insurance.
No actual structural damage to mast or boat was found.
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Old 21-12-2011, 02:35   #22
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Re: Lightning strikes, any real experience?

It seems so much like a bullet the entry is small there's damage along its path but the exit can be huge, there was one in the Whitsundays on an Aluminium boat as well, the underbody had been epoxy and micro balloon filled, it blew areas of fill off the bottom.

I'm favouring building a small faraday cage with spare gps and vhf inside, only going down this line because Caribbean seems to be prevalent with strikes.

Fairly sure a proper cage can be made of steel 3mm perforated plate.
Cheers All....
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Old 21-12-2011, 02:51   #23
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Re: Lightning strikes, any real experience?

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Originally Posted by Maine Sail View Post
I figured aluminum foil prevented noise and acted as a shield on coax wire so why not give it a try, it's cheap.... Well, it did not work, and I soon after discovered that you need real steel to create a Farday cage that will work..
I have always done the same. I am surprised it did not work, but you have done a practical test and you cannot better that sort of information.
I would guess the electrical conductivity at the joins to the aluminium foil where it overlapped were not good enough.
Have you any theories why it did not work ?
Any metal, the more conductive the better, should work and there are lots of other suitable containers such as the aluminium cylinders that good scotch and champagne come in, or metal water pipe.
Any thoughts?
Why the need for steel ?
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Old 21-12-2011, 02:55   #24
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Re: Lightning strikes, any real experience?

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Originally Posted by noelex 77 View Post
I have always done the same. I am surprised it did not work, but you have done a practical test and you cannot better that sort of information.
I would guess the electrical conductivity at the joins to the aluminium foil where it overlapped were not good enough.
Have you any theories why it did not work ?
Any metal, the more conductive the better, should work and there are lots of other suitable containers such as the aluminium cylinders that good scotch and champagne come in, or metal water pipe.
Any thoughts?
Why the need for steel ?
Not sure maybe the magnetic side comes into play being ferrous? I'm only a boilermaker so can't help beyond the suggestion.
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Old 21-12-2011, 03:10   #25
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Re: Lightning strikes, any real experience?

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Not sure maybe the magnetic side comes into play being ferrous? I'm only a boilermaker so can't help beyond the suggestion.
Yes good thought.
BTW there is no such thing as “only a boilermaker”, I wish I could weld like the experts.
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Old 21-12-2011, 03:10   #26
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pirate Re: Lightning strikes, any real experience?

Had a strike..?? in Andraitx, Mallorca...
A Dutch couple, my Mate and myself were sat around the table in the saloon chatting... they swore blind a blue flash went between us across the table...
I didn't see it but maybe I'd blinked...
Anyway... it took out all the electric's that were connected.. GPS, VHF, etc...
Have I done anything about boats I've had since... no...
I figure a direct hits gonna blow my little plastic shell to bits...
and I only use portable devices switched on only when needed...
Call me a 'Fatalist...'
"Don't Worry... Be Happy..."

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Old 21-12-2011, 03:23   #27
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Re: Lightning strikes, any real experience?

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Originally Posted by noelex 77 View Post
Yes good thought.
BTW there is no such thing as “only a boilermaker”, I wish I could weld like the experts.
I did my trade with Comalco there were probably only 12 people in Queensland that could weld ally with Mig and Tig in my first year i had to teach the teachers lol. So different now! In the end with Mig you could close your eyes and weld by sound!!! Happy to give you the skills don't need them anymore...CATCH!!!
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Old 21-12-2011, 03:24   #28
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Re: Lightning strikes, any real experience?

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Originally Posted by boatman61 View Post
Had a strike..?? in Andraitx, Mallorca...
A Dutch couple, my Mate and myself were sat around the table in the saloon chatting... they swore blind a blue flash went between us across the table...
I didn't see it but maybe I'd blinked...
Anyway... it took out all the electric's that were connected.. GPS, VHF, etc...
Have I done anything about boats I've had since... no...
I figure a direct hits gonna blow my little plastic shell to bits...
and I only use portable devices switched on only when needed...
Call me a 'Fatalist...'
"Don't Worry... Be Happy..."
As good a plan as any lol... scary stuff!!!
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Old 21-12-2011, 06:04   #29
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Re: Lightning strikes, any real experience?

Quote:
Originally Posted by noelex 77 View Post
I have always done the same. I am surprised it did not work, but you have done a practical test and you cannot better that sort of information.
I would guess the electrical conductivity at the joins to the aluminium foil where it overlapped were not good enough.
Have you any theories why it did not work ?
Any metal, the more conductive the better, should work and there are lots of other suitable containers such as the aluminium cylinders that good scotch and champagne come in, or metal water pipe.
Any thoughts?
Why the need for steel ?
I was told by one of the electronics makers I spoke with, can't remember which one, that it's best to be steel to actively quench the magnetic pulse. Apparently aluminum does not do this as well, especially aluminum foil.

The funny thing was that this GPS fired up after the strike, once. I then assumed it worked and my foil trick also worked. When the lightning surveyor was there for the insurance survey he had just come from a boat were a bunch of non-plugged in electronics that had also been fried. I went to show him how successful the tinfoil was and we hit the button, it powered up, then the screen went pop and it shut off. Tried three new sets of batteries, banged on it, fiddled with it for about 5-10 minutes and then the surveyor added it to the list.... Something was compromised and worked for a short while, 30 seconds or so after the strike, but then it died.

My Garmin 176, also not plugged in, has no button responses but if you put in a fresh set of batts the screen comes on, but that's about it, can't do anything with it and Garmin no longer supports it... Lightning works in odd ways for sure... The iPod was complete toast and the EPIRB test light worked but when I sent it back, just in case, they told me the board was bad and it would not TX..

Oh I forgot our daughter also had an electronic learning game called a Leapster that was also toasted...
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Old 21-12-2011, 06:22   #30
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Re: Lightning strikes, any real experience?

Just wrapping your GPS in foil, like you might wrap a sandwich, is very likely useless. As would likely be any number of metal cases or such. The enclosure must be conduct in all directions all around the object. All the edges must conduct to the adjacent edge along their entire length. It does not need to be ferrous. Aluminum is fine.

I'd wrap it neatly like a gift box would be wrapped. The first two edges might be tightly folded together repeatedly (like a dry-bag is). Then the same for the open ends.

The worst would be going around and around the object with multiple layers. Wrap it like you would a wet yummy Pastrami sandwich that must not leak.

Note that aluminum to aluminum conduction in a marine environment is dubious at best. Perhaps a paint can is the best common item? Or a metal cracker box?
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