How To Avoid Ligthening Designing A Sailing Yatch

Discussion in 'Boat Design' started by metin_mehel, Apr 11, 2014.

  1. metin_mehel
    Joined: Jul 2009
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    metin_mehel mech.eng.

    Hello,
    How to avoid lightening by design?
     
  2. Rurudyne
    Joined: Mar 2014
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    Rurudyne Senior Member

    If I recall correctly from what I've read you can pass a wire down to somehow ground the boat as part of a lightning rod set up, something a NA can help you with.
     
  3. CDK
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    CDK retired engineer

    Use a non-conducting mast. Avoid all sharp metal objects, including (long) antennas.
     
  4. Richard Woods
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    Richard Woods Woods Designs

  5. Eric Sponberg
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    Eric Sponberg Senior Member

    Check spelling for meaning, please. "Lightening" means to make lighter, as in removing weight. If you mean the electric bolts of light that come down from the sky, that is "lightning." There is an ABYC standard, TE-4, for adding lightning protection to a boat. It does involve adding a terminal at the masthead, connecting that to a wire of a certain minimum size that runs down the mast, which in turn connects to a ground plate of sufficient area that is fastened to the outside of the hull.

    Also, the term is "yacht", which rhymes with "lot", and not "yatch" which rhymes with "latch".

    Sorry to be nit-picky, but those two words are often mis-spelled and seeing them wrong is very grating.

    Carry on.

    Eric
     
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  6. Navygate

    Navygate Previous Member

    The best way I've found to avoid a whole lot of lightning issues is to stay out of stormy weather...
     
  7. metin_mehel
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    metin_mehel mech.eng.

    Thanks for the beautiful answers. I dont believe in most boat use special equipment to be protected from Lightning.
     
  8. PAR
    Joined: Nov 2003
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    PAR Yacht Designer/Builder

    Small craft unfortunately, don't use lightning protection, mostly because of the investment in both the boat and the protection. Larger craft generally do, again because of the investment.

    NASA has a lot of data on lightning protection and is likely the world leader on the subject. TE-4 (ABYC), ISO 9001, plus others, like CE also have recommendations and guidelines for protection.
     
  9. Eric Sponberg
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    Eric Sponberg Senior Member

    Having inspected a lot of lightning-struck masts from boats that were sitting in their marina slips, at anchor, or on a mooring, I can say that you can't always avoid lightning. It is better to have suitable lightning protection.

    Eric
     
  10. Eric Sponberg
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    Eric Sponberg Senior Member

    But they should. Certainly, every sailboat mast is a potential lightning strike site, and getting struck by lightning can cause a lot of damage on the boat at least, and be lethal at worst. Every carbon fiber mast should have lightning ground protection because to not have it very nearly guarantees destruction of the mast, should it be struck by lightning.

    Eric
     
  11. BertKu
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    BertKu Senior Member

    One should understand lightning strikes. It is not one discharge, but short bursts of up to 40 of discharge currents of up to 50.000 Ampere each. It appears one burst, but it is not, it is not one massive discharge. There are two types of lightning strikes, one from earth/sea to the clouds and the majority from clouds to the earth/sea. It depends whether there are electrons short in the cloud or too many. One could build a high voltage ionizer of let say 200 KVolt and place that at the top of the mast. The problem is, if you are unlucky and you have a discharge from earth to cloud, you may even help the lightning strike, by having created an easy path for the lightning. I haven't seen an ionizer, which could detect a early guess whether it is a positive or a negative discharge and let the ionizer quickly reverse polarity. Therefore to play it safe, I, personal prefer a kind of Faraday cage, whereby the lightning is re-routed via a number of wires from the top of the mast to the outside of the boat/seawater. The previous website had one example. The problem from a single wire from the top of the mast straight to the shortest earth/seawater ground plate, induces quite a voltage potential in your body and you may still kick the bucket. While as a Faraday cage one has a better chance. The previous mention website by Richard Woods >> http://www.marinelightning.com/ shows an example. I prefer to stay alive.
    Bert
     
  12. jonr
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    jonr Senior Member

    In the case of an aluminum mast, does such a wire running down the mast serve any purpose?

    Based on personal experience, I recommend disconnecting the radio antenna wire when you don't need to use the radio. Maybe do the same for any masthead wires.
     
  13. BertKu
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    BertKu Senior Member

    If you have an aluminum boat with a aluminum mast, would you then not have a kind of Faraday cage, thus your wires running from the top of the mast creates a kind of Faraday cage. I have the gut feeling you have a better chance to survive. Anybody who could back this up with a personal experience ?? With the mast wires on a aluminum mast, provided the the end of the wires are making good contact with the sea/groundplate. It would form a kind of Faraday cage also.
    Indeed not a bad idea. Special to disconnect the radio also. Bert
     
  14. Eric Sponberg
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    Eric Sponberg Senior Member

    Yes, the wire provides the easiest clear path to ground. If you don't have a wire, then the lightning can travel either down the mast or down the rigging and from there it can side flash anywhere--to a piece of hardware, a stanchion, or the nearest human being. A wire is no guarantee that you and your boat are protected, of course, it just increases the chances of your safety. Disconnecting your wires to your electronics is no guarantee that lightning won't go there--it can still travel down the wires and side flashes are powerful and unpredictable--they can jump many feet in any direction. Lightning is dangerous and costly if hit. Stay away from it if at all possible, and it is recognized that you cannot avoid it 100% of the time.

    Eric
     

  15. BertKu
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    BertKu Senior Member

    I am not completely in agreement. If you can create a decent Faraday Cage with all the wires, one could stay very safe within that environment. The question is, can you convert your boat properly to a Faraday Cage. If not, you are right. If yes, you have a good chance to survive. Bert
     
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