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Thread: Lightning protection for a wooden boat with dyneema standing rigging

  1. #71
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Hi MN Dave,

    Politely disagreeing with the statement of the strength of a lightening strike in the air vs ground. Kirchhoff's current law tells me the lightening strike current is the same entering the structure as leaving it. Sure, it's not exactly the same due to some losses, but I would consider those negligible.

    Cheers,
    Mark

  2. #72
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Mark0 View Post
    Hi MN Dave,

    Politely disagreeing with the statement of the strength of a lightening strike in the air vs ground. Kirchhoff's current law tells me the lightening strike current is the same entering the structure as leaving it. Sure, it's not exactly the same due to some losses, but I would consider those negligible.

    Cheers,
    Mark
    I agree that it does sound counterintuitive.

    That may be the case if the aircraft is under the cloud and a cloud to ground strike passes through it. In the air, that is apparently not the usual situation.

    https://ntrs.nasa.gov/archive/nasa/c...9780003081.pdf
    NASA Reference Publication 1008
    Lightning Protection of Aircraft
    Page 39
    When the aircraft is attached to the leader, some charge (free electrons) will flow onto the aircraft, but the amount of charge which can be taken on is limited by the aircraft size. The measure of the aircraft's ability to store charge is its capacitance.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  3. #73
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Isn't that referring to the the leader ? but the high current return stroke does flow through the aircraft as per page 41, figure 24a.

    Too bad we can't use the leaders to charge batteries before the return stroke

  4. #74
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    Aug 2017
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    Melb, Vic, Aus
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    I dunno what your all worried about.

    https://www.youtube.com/watch?v=szOnAUnuMLk[/VIDEO]

    Skip to about 47 seconds

  5. #75
    Join Date
    Sep 2007
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    I've been closer then that to a strike on a tree, not more than 40'. It gives you the heebie jeebies.

  6. #76
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    Sep 2007
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Mark0 View Post
    Hi MN Dave,

    Politely disagreeing with the statement of the strength of a lightening strike in the air vs ground. Kirchhoff's current law tells me the lightening strike current is the same entering the structure as leaving it. Sure, it's not exactly the same due to some losses, but I would consider those negligible.

    Cheers,
    Mark
    If you're dealing with 10,000 or 100,000 V it isn't going to matter on your boat. You will either live or die.

  7. #77
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    The following information detailing the mechanics of lightning ground systems is extracted from an article in WoodenBoat magazine No. 136, May/June 1997, and referenced in an article about lightning damage by Jonathan Klopman and Joshua Moore in WB No. 215, July/August 2010.
    https://www.woodenboat.com/lightning-ground-systems

    Quote Originally Posted by navydog View Post
    If you're dealing with 10,000 or 100,000 V it isn't going to matter on your boat. You will either live or die.
    100,000V smarts, but the voltage of lightning can reach 1,000,000,000V and the temperature runs up to 50,000F. So while you might have guessed a little low, you got the end result right.
    Last edited by MN Dave; 07-16-2018 at 11:38 PM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

  8. #78
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Geftb View Post
    I dunno what your all worried about.

    https://www.youtube.com/watch?v=szOnAUnuMLk[/VIDEO]

    Skip to about 47 seconds
    They speak French but cuss in English!!

  9. #79
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    Sep 2007
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Dave Hadfield View Post

    Of course, the real danger from a t-storm is not the lightning.
    I'm sure everyone heard the about the a Duck Boat tragedy.

    The National Weather Service said wind gusts were as strong as 60 mph and caused 3-foot waves. Strong thunderstorms with straight-line winds.

  10. #80
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    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by navydog View Post
    I'm sure everyone heard the about the a Duck Boat tragedy.

    The National Weather Service said wind gusts were as strong as 60 mph and caused 3-foot waves. Strong thunderstorms with straight-line winds.
    Dyneema rigging do you think?

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