Lightningrod

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  • 25th January 2008 at 9:47 am #11002

      Whenever I sail and see a thunderstorm closing-in on me, I get the creeps. Thinking that lightning will hit the boat i'm almost paralized with fear. So I throw chains or jumpercables overboard swung around the stays. Last year a small motoryacht that was sailing half a mile from us got the full blow of a massive lightning-flash.
      Now that our boat is ashore I'm thinking of bolting four stainless steel plates to the rudders and connect all the stays, cokpit-tent support-rods and mast to them.
      Would that protect me enough?
      regards Juup

      25th January 2008 at 7:27 pm #11633

        The following link gives some information

        http://www.cdc.gov/nasd/docs/d000001-d000100/d000007/d000007.html

        One thing I do recall from a lecture I once went to on lightning rods was that it is not just the resistance of the path to ground that is important but, because the rate of rise of the lightning current is very high, the inductance of the path needs to be kept to a minimum. This means keeping the path as straight as possible and with all bends kept to maximum possible radius (sharp bends as one sometimes sees in lightning conductor installations are apparently very bad). The article I linked mentions a minimum radius of 8 inches.

        3rd February 2008 at 11:27 am #11634

          The consensus is that rods just encourage the problem and may still fry your rigging! Mind you, with that awesome cockpit tent frame of yours, you have a ready made faraday cage installed, just sit under that and nothing will touch you!

          10th February 2008 at 6:21 pm #11635

            Monohulls often bond from the mast to the keel, Too many bends on a cat. Some boats are fitted with a ground plate, also often used on an SSB instalation. It would be best to fit it under a chain plate as best possible to avoid bends, then bond it to the rigging with wide copper strap. praying may work also! Regards Geoff Linter

            15th February 2008 at 10:31 am #11636

              @pastasimon wrote:

              The consensus is that rods just encourage the problem and may still fry your rigging! Mind you, with that awesome cockpit tent frame of yours, you have a ready made faraday cage installed, just sit under that and nothing will touch you!

              Given that the surface of the GRP will be pretty much covered in damp salt I don't think you can rely on it providing enough isolation to significantly reduce the chances of being struck so I doubt that better grounding of the mast will increase your chances of being struck.

              I have found this link:-
              http://www.pas.rochester.edu/~cline/ASK%20lightning%20strike/ASK%20accident%20report.htm which shows that significant srtuctural damage occurs to composite structures involved in lightning stikes (gliders in this case)

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