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4318Re: [campernicholson] Lightning Protection

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  • Graham Norbury
    Jul 2, 2008
      When I used to own Luna Azul (CN35#220), I installed a mast grounding system consisting of a very large sintered bronze plate mounted on the port side of the hull, as close to the base of the mast as I could manage.  Connection to the mast comprised of a 4 AWG cable run inside a short section of PVC tube for additional insulation against arcing out to nearby metal.  Due to the proximity to nearby metal water tanks, I also connected bonding straps from the tanks directly to the grounding shoe.

      Shrouds were left unbonded, on the (possibly misguided) principle that it was better for a high energy strike to dissipate directly down the mast, than to spread out through every available piece of on-board metal.

      One year after installing the grounding system, the mast took a direct strike during a severe storm while at anchor in Town Creek, Oxford, MD.  Whilst the strike wiped out all our electronics, melted the windex and blew away the VHF antenna, there was no damage to the hull, underwater metals or grounding shoe.  My wife and I were aboard at the time, and noted no weird hair raising effects or electric shocks, and the only reason we knew we'd been hit was the small "clonk" of the melted windex hitting the deck right after the immense flash-bang.


      Albert G. Boyce wrote:

      I am wondering what other Nicholson 35 owners have done for lightning
      protection. I have developed a keen interest in lighting protection
      after getting caught out on the Chesapeake in a thunderstorm last week
      and getting a mild electric shock at the helm while steering the boat.
      Quite a wake up call. I have hull number 132 and there is a small
      sintered bronze plate on the outside of the hull that is connected by #8
      wire to the mast.

      None of the shrouds, stays, lifelines, stanchions, or any other metal
      objects are grounded or otherwise connected to this plate

      I look forward to hearing what lightnting protection arrangements others
      have in place on their boats.

      Al Boyce
      Discovery CN35 #132

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