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Old 13-07-2009, 09:30   #1
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Lightning

I have read and read about lightning vs sailboats but i have never met anyone who has any "real" knowledge of it, but i was curious of how bad of a problem lightning is for cruising. I sail around the mississippi gulf coast and its a concern for me, i read about lightning protection and then i read again how they are a myth etc. Just wanted an opinion from som real cruisers
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Old 13-07-2009, 09:57   #2
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Actually being struck by lightning includes a lot of variations. On the dark side you get hit and it blows out the rudder post or a through hull and sinks the boat. Happens. How common not very. What is possible is almost infinite. The near misses are obviously common and can result in little or no damage.

Being inducted while at a dock is very common and usually can trash radios and instruments. It can happen from being plugged into the dock electrical system since that system can be inducted and the over voltage sent directly to you using your power cord. This is very common and not unlike the problems you could have with your home. My neighbor got one and it did both the house and the boat at the same time since his boat is very close to the dock and a tree in the parking lot was struck. The power line was inducted and the house and boat were damaged. When at a dock it's best to not be plugged in unless you have to be. Just to note neither boat on either side of his were damaged at all.

A well wired boat with bonding to provide good grounding is a basic start. It's going to help with any SSB or HAM radio you might install as well. This is one of those times where if you do all that it will help more than just lightning protection.

There are a whole host of products snake oil and other assorted gadgets out there. This topic comes up a lot here and you can search for some of them. The number of actual strikes vary by type and frequency.

Lightning is not a myth but it's not common. If you got a large direct strike it could sink the boat and or kill you. There is no 100% protection system that can prove it works all the time. Many of the protection products and systems are not well substantiated with direct test results. They all come with a great story and set of claims to match. Some are mostly junk science and others based on facts that have been extrapolated from unrelated studies.

If you find one you like and sleep better then I would stop looking.

You can do a search on the word Lightning in the search box you get about 400 threads. I would say the topic has played out as much as is possible. Personally, I have a decent bonding and ground system on the boat and I consider it enough. My neighbor did install a surge protector on his VHF antenna. He was hit twice over 3 years and lost radios in both strikes as well as all his Ray marine Instruments. he was an engineer that built cell phone towers. They had a lot of lightning stories too.
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Old 13-07-2009, 13:03   #3
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Hi, I'm curious: How does one go about grounding the wiring on a sailboat? Do you use the keel, a thru-hull, or just drop a wire overboard into the brine?
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Old 13-07-2009, 13:38   #4
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It is dangerous stuff, a fisherman in a small boat was struck, not killed but hospitalized by lightning last weekend in Cocodrie LA. Not too far from you.
Some folks swear by those "spiky" dissipators on the mast.
Be careful out there,
Good luck
Steve
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Old 13-07-2009, 14:05   #5
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Hi, I'm curious: How does one go about grounding the wiring on a sailboat ...
Check out a few previous discussions.
If you still have questions, and you should, don’t hesitate to ask.

Lightning Protection

lightning strikes/ avoiding them?

lightning strike prevention/protection against?

Lightning Safety

Lightning

and more ➥ lightning ground - Google Search
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Old 13-07-2009, 16:04   #6
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Lightening avoidance....It's subject debated almost as much as anchors. I dont believe there is any factual data on whether any of the avoidance schemes actually work.... just theorys. (how hard is it to divert a bolt of lightening from it's direct path anyway, it's super powerful, traveling super fast, in a primarily random direction once "launched") The amount of trees and masts hit indicate that a bolt will divert a minor amount at the very end. Damage avoidance may be possible, but it better be stout with a lot of conductance... Radar may be the best avoidance tactic. In Annapolis Maryland, in the marina, everything on my masthead was melted with no damage or indication of it occurring below. Discovered it when inspecting the mast. There were exit "carbon traces" on the upper stay tangs, so it must have went down the stays and jumped to the water.... No electronics damage (other than the masthead stuff!) at all... I always tracked thunderheads on the radar and took an early tack the other way!
In San Carlos Mexico, I was out in the dingy catching Sierra Mackeral just outside the bay and a fast squall came through (fishing was too good to go in!), on my way in I got drenched and about 4" of water in the dingy. (2 hp Johnson!) A moored trimaran had one of those fuzzy lightening devices on his masthead... one of the first I'd ever seen and had been noticing it every time I passed. As I was putting by, I actually saw the masthead get hit with lightening! The shock wave almost knocked me out of the dingy and I couldnt see well for a minute, but everything was obliterated on the masthead and a little wisp of smoke was rising.....
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Old 13-07-2009, 16:42   #7
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we took a direct hit while in the marina here in CHarlesston. Took out everything that was low voltage. Even got the PC and it was not even plugged in.
Blew up the batteries and we assume went out the engines. Diane had her foot on the compression post and took a jolt but was told she would disapate in a few weeks and would be fine!!!!!!!!
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Old 13-07-2009, 18:17   #8
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This will help. Like Indy says..."Never tell me the odds!" Read: BoatUS.com - Seaworthy Magazine
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Old 13-07-2009, 18:32   #9
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Diane had her foot on the compression post and took a jolt but was told she would disapate in a few weeks and would be fine!!!!!!!!
Well I don't know... if Diane dissipates, is that fine? ;-)

cheers,
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Old 13-07-2009, 18:33   #10
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I had it suggested to me that a precautionary measure to take when it is possible that the boat could be struck by lightning was to place a handheld GPS and VHF in the (cold) oven. I believe the thought was that a stainless marine oven would act as a sort of faraday cage and protect its contents from damage.

Feasible or myth?
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Old 13-07-2009, 19:25   #11
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Hey Paul,
Quote:
The near misses are obviously common and can result in little or no damage.
Wouldn't a near miss be a HIT as in that lightning nearly missed me.
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Old 13-07-2009, 20:48   #12
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I had it suggested to me that a precautionary measure to take when it is possible that the boat could be struck by lightning was to place a handheld GPS and VHF in the (cold) oven. I believe the thought was that a stainless marine oven would act as a sort of faraday cage and protect its contents from damage.

Feasible or myth?
Myths and rumours, sometimes they work sometimes they donít. How do you prove something that happens so infrequently.
Take your best guess, cross your fingers and all appendages (confuses the lightening), drink beer (being more relaxed helps dissipate a potential charge) and stay away from the mast.
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Old 13-07-2009, 20:55   #13
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Myths and rumors, sometimes they work sometimes they don’t. How do you prove something that happens so infrequently.
You can't. You can do things that have serious benefits like bonding and good ground systems in general. Crossing your fingers only matters when you have at least done the "dumb stuff". Frankly, using the radar to try and "not be there" works for me as the most proactive thing you can do. You just can't do it every time. There is always a what if that does not work but there is never an answer to the last possible what if that does not work because it's too late and this is moving at the speed of light. It's like the concept of turning off the light in the bedroom and being in bed before the light goes out. If you could go that fast you would burst into flames from spontaneous combustion.
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Old 13-07-2009, 21:41   #14
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Take your best guess, cross your fingers and all appendages (confuses the lightening), drink beer (being more relaxed helps dissipate a potential charge) and stay away from the mast.
I suppose I was being a bit too facetious.

Learn as much as you can about lightning and do everything you can to prevent and if not to direct the strike.

My best guess is to have a straight a line as possible for a charge to be carried down your lightening rod, the aluminium mast, and then with as little deviation as possible straight down using a massive copper and bronze conductor through the hull to a ground plate in the seawater. No bends, turns or constrictions.
During a lightening storm there is nothing to do but relax, it is too late.
There is no guarantee what path a strike will follow, sometimes it appears to be random chance. Boats next to us that followed all the recommendation have been hit while the next boat over from them who had done nothing were spared.
There must be some mechanism to explain the path of a strike that one day will be found.
We have been lucky so far.
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Old 13-07-2009, 22:13   #15
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Ah the randomness of the fickle finger of fate. I have been the recipient of 2 different direct hits, both were on steel boats and one hit, took out my SSB antenna, and one of the cards in the SSB antenna coupler. The other took out my Gps, antenna and antenna wire. On the one boat, I was on, it had been struck 3 times in a space of less than a year. I have heard one story about a fiberglass sailboat that took a direct hit on the mast and it blew out the grounding plate on the bottom of the boat and the owner had to dive over the side with a blanket to stuff the hole full. I still like the grounding plate, but I believe there is such a random factor involved that one can never predict the results of a lightening strike.
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