Lightning

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  • 06 Sep 2023 13:57
    Reply # 13250684 on 12250597
    Deleted user

    As I understand it, there are two issues, strike prevention and strike mitigation. 

    To mitigate a strike, a fat straight conductor with a blunt aerial and a sizable seawater contactor can safely carry the huge current down and into the water. The contactor can be any metal you want, but copper or titanium will last longer than more reactive metals.

    Strike prevention can be helped along by having a good corona discharge element in parallel with the blunt aerial, so that when the local field strength builds up, enough current can flow to limit the field strength and make a high current strike less likely. Several companies will sell you expensive gadgets such as https://www.forespar.com/products/boat-lightning-static-dissipater.shtml

    I'm having difficulty finding the link again, but you can DIY with some graphite fabric cut to expose thousands of fiber ends, then electrically bonded to the lightning rod at the upper end. When the field rises, a silent corona discharge sprays into the air. No active parts needed.

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  • 22 Jan 2022 15:56
    Reply # 12300018 on 12291330
    Deleted user
    Anonymous wrote:

    Am I a lightning expert?
    Absolutely not.
    Do I live on a ranch in Africa that receives most of its rain from thunderstorms?
    Yup.

    The light and sound shows we get on my ranch can be awesome and yes, there have been two occasions where a direct hit on the homestead has fried almost everything including all my computer equipment despite all precautions such as surge protection. But even the not so direct hits cause tremendous fluctuations in our electricity supply that reaches the ranch via overhead cables. This it does to the point that at least 80% of these rain bringing storms result in power outages ranging from minutes to days.
    I have, at no small cost, had to replace borehole installations and pumps twice.
    It's a price we pay for the life giving rain that nourishes the crops and pastures.

    Below are a couple of my more spectacular images of lightning on the ranch.

    It is unbelievably powerful and, especially when up close, unbelievably noisy and a killer.
    We have lost livestock and a giraffe to its lethal power. We regularly lose tall trees on the ranch and in the early season, when the lightning does not come with rain and the farm is dry as tinder from the previous winter, we can get veld fires. Lone trees in open fields are favourite targets for the exchange of ions.

    Yachts on the open water and in marinas, are much like lone trees in an open field or a small forest.

    Is there a way to totally prevent your boat from being 'the chosen one' in the trade of electrical charge between heaven and earth?
    No.

    But there are things that can be done to make it a little less likely that your boat will be 'the chosen one' in that energy exchange.

    This video is one of the best I have watched at conveying the principles involved and some of the things that can be done.

    Luck is a thing but I have always lived with the motto that the harder and smarter you live, work and play the luckier you become.

    Fair winds to all and may the lightning you encounter entertain and not maim.


      Beautiful photos!!   I too live in a lightening prone area.  I've had lightning strike within about 10' of where I was standing.   I also had a lightening bolt strike a cut bank on the highway between here and town between my pickup and the car in front of me... about 6 car lengths between us, traveling at 70 mph (116 kph).   The dirt bank exploded  in a dust cloud, and the crash of thunder was intense!   My  neighbor in the car ahead apparently took it as a message from God that he was not supposed to go to town that night and turned around in a driveway.... God and I had a good laugh about that   ;-)   as I continued on my way.  I've been in the mountains at close to 10k feet elevation in a violent thunderstorm, violent hail and rain.... I ignored the rule about trees, and sheltered in a patch of trees figuring the odds were in my favor that it would not hit the one I was under.... It didn't, but it did strike one quite close by.   Herding sheep many years ago (1979), my metal covered sheep wagon was on a small hilltop, and I was in the pasture below when a bad one hit....... violent hail... painfully large, not a tree in the area, I fled to the "safety" of my camp, expecting to be struck dead at any moment........ There wasn't a bolt with my name on it that afternoon..... It ignored my horse who was on a picket next to camp.....  horses are famous for being hit, and that one would not have been a great loss to me... unpredictable and dangerous because of it....But I did lose a 3 year old ewe and two fine lambs??   A few years ago two lady friends of mine were driving... basically a new car... and were hit.  They were unharmed naturally, but the car was considered a total by the insurance company........ all the electrical was destroyed... or so I was told.   


         Lightening is something to be taken seriously.   There is wisdom in the second to last paragraph of your post..... I too try to live by that.....  Thanks for the video link!

    the harder and smarter you live, work and play the luckier you become.

    Last modified: 22 Jan 2022 16:17 | Deleted user
  • 21 Jan 2022 20:32
    Reply # 12295018 on 12292201
    Anonymous wrote:

    I do remember another big storm on the approach to the Tuamotus. On that occasion, the mitigation that I put in place was to act on the battlecry of the knights in the movie Monty Python and The Holy Grail.

    "Run away! Run away!"

    LOL
  • 21 Jan 2022 12:49
    Reply # 12292201 on 12250597

    Risk always needs to be assessed and quantified. If I had frequently sailed in an area where thunderstorms were common and the risk of a strike was high, I would have probably added a lightning rod bonded to copper ground plate. But I didn't.

    I do remember another big storm on the approach to the Tuamotus. On that occasion, the mitigation that I put in place was to act on the battlecry of the knights in the movie Monty Python and The Holy Grail.

    "Run away! Run away!"

  • 21 Jan 2022 11:35
    Reply # 12291943 on 12291529
    Anonymous wrote:

    Yes, luck is a major factor.

    In your case it certainly was 'lucky' David.

    Pure chance is not a reliable friend to all.

    Some relatively low cost mitigation can improve one's personal chance.

    Do you think mitigation efforts are pointless?

    That the luck of the draw cannot be improved on?
  • 21 Jan 2022 09:06
    Reply # 12291529 on 12250597

    Many, many years ago, I was sailing up the English Channel in Lliutro (GRP hull, cast iron keels, hybrid alloy/wood mast) and sailed through a massive thunderstorm. Nothing and nobody else around me for miles. Lightning was striking the water all around me, and I could swear that I heard it sizzle. Yet though I was a "lone tree on the veld", and hadn't done anything to mitigate damage, I wasn't struck. If I had been, I probably wouldn't be sat here writing this. Yes, luck is a major factor.

  • 21 Jan 2022 07:38
    Reply # 12291330 on 12250597

    Am I a lightning expert?
    Absolutely not.
    Do I live on a ranch in Africa that receives most of its rain from thunderstorms?
    Yup.

    The light and sound shows we get on my ranch can be awesome and yes, there have been two occasions where a direct hit on the homestead has fried almost everything including all my computer equipment despite all precautions such as surge protection. But even the not so direct hits cause tremendous fluctuations in our electricity supply that reaches the ranch via overhead cables. This it does to the point that at least 80% of these rain bringing storms result in power outages ranging from minutes to days.
    I have, at no small cost, had to replace borehole installations and pumps twice.
    It's a price we pay for the life giving rain that nourishes the crops and pastures.

    Below are a couple of my more spectacular images of lightning on the ranch.

    It is unbelievably powerful and, especially when up close, unbelievably noisy and a killer.
    We have lost livestock and a giraffe to its lethal power. We regularly lose tall trees on the ranch and in the early season, when the lightning does not come with rain and the farm is dry as tinder from the previous winter, we can get veld fires. Lone trees in open fields are favourite targets for the exchange of ions.

    Yachts on the open water and in marinas, are much like lone trees in an open field or a small forest.

    Is there a way to totally prevent your boat from being 'the chosen one' in the trade of electrical charge between heaven and earth?
    No.

    But there are things that can be done to make it a little less likely that your boat will be 'the chosen one' in that energy exchange.

    This video is one of the best I have watched at conveying the principles involved and some of the things that can be done.

    Luck is a thing but I have always lived with the motto that the harder and smarter you live, work and play the luckier you become.

    Fair winds to all and may the lightning you encounter entertain and not maim.

    3 files
    Last modified: 21 Jan 2022 07:52 | Anonymous member
  • 20 Jan 2022 23:36
    Reply # 12290079 on 12250597

    I have come to the conclusion that avoiding lightning strike is something that happens more by good luck than good management.  I dare say it would exercise me more if I lived in Chesapeake Bay.  However, it is something I am fatalistic about, unless, of course, I'm sailing in a thunderstorm, when I wish I had 100% effective protection!  Still, I reckon I am more likely to sustain serious damage from another vessel than from lightning and there's nothing I can do to prevent that, either.  In the meantime, watch the forecast and enjoy your boat.

  • 19 Jan 2022 17:10
    Reply # 12281861 on 12269732
    Amos wrote:

    I have an aluminum boat with an aluminum mast and while I worry about a lot of things, lightning isn't one of them.

    This does seem like the best solution. If I ever find the means to have an all-aluminum boat then that would be my first choice. Maybe someday I will move out to the PNW when a JRA member offers me a good deal on such a boat?

    My fiberglass boat was built around 1982 if I remember correctly. From the factory there was a substantial electrical connection from the mast, to the mast step and to the steel compression post. The compression post had a large (maybe 2 gauge?) braided copper wire running to the internal lead ballast, aft of the compression post.

    I am not convinced a powerful lightning strike would peacefully go around that bend and gently discharge through the lifting keel to the ground.

    I suspect, without evidence, that there is a wide variation in power between different lightning strikes. I imagine the smaller discharges may safely pass through the grounding systems of fiberglass sailboats. I think it is also reasonable to assume that a very powerful bolt of lightning will destroy a fiberglass boat regardless of how much protection was built into the design.

    Last modified: 19 Jan 2022 19:00 | Anonymous member
  • 19 Jan 2022 15:48
    Reply # 12281458 on 12250597

    lighting is around all the time ,as static , as good as any is a welding cable and plate clamped to the mast before it enters the boat if your boat is not made of mettle chuck it in the water wnen it gets thundery ; be aware if the plate is in the water not to get between mast and bare cable because your mast is acting as a scink for static all the time .      my steel boat had a steel mast and was bolted to the keel and I used 6 erosion plates on the keel never to be painted ; while in france lightening hit the old wind jammer next to me and left me alone ,  in another case my friend got hit by lightening and it burned all his cabling ' ps welding cable is usually  insulated .     

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