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Lightning Protection

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  • Albert G. Boyce
    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
    Message 1 of 12 , Jul 1, 2008
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      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
    • Colin Campbell-Dunlop
      Dear Albert, My boat, Trutz #225 has lightning protection. It was originally built for a German owner who had plans (and all the charts) for a trip down the
      Message 2 of 12 , Jul 2, 2008
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        Dear Albert,

         

        My boat, Trutz #225 has lightning protection.  It was originally built for a German owner who had plans (and all the charts) for a trip down the West coast of Africa .  He was clearly expecting to encounter some thunderstorms.

         

        It sounds like a similar installation to your own.  The mast is grounded via a cable attached to the port side of the mast just above the mast heel.  This wire goes to a sintered metal grounding plate which is bolted through the hull.  This sits on the port side of the hull about a foot below the waterline.  We also have another pair of these plates stbd aft but I think that they are to do with the disused SSB installation. 

         

        I have done a bit of research on this subject and all I can say is that the arrangement that we have on board is probably not really up to the job.  This isn’t a problem in the UK where thunderstorms are not quite so regular.  However, for use in sub tropical or tropical areas you might want to talk to a specialist.  The problem seems to be that a really big strike might not be properly dissipated in time leaving you with a lot of high voltage flying around in the rigging and bouncing off of important things like instruments and crew.  Not a nice prospect.  Those sintered metal plates are very good at spreading the load though so maybe adding another one or two of those and upgrading the cable might give some peace of mind. 

         

        There are some very specialized companies out there who will no doubt charge you a lot of money to upgrade your protection but, at the end of the day, it seems that keeping your fingers crossed is the best policy.  You probably already know this but apparently if you can disconnect all your valuable electronics and put them in the oven during a storm they will be protected from the strike. 

         

        Hope this helps in some way.

         

        All the best

         

        Colin & Jo

         


        From: campernicholson@yahoogroups.com [mailto: campernicholson@yahoogroups.com ] On Behalf Of Albert G. Boyce
        Sent: 02 July 2008 03:06
        To: campernicholson@yahoogroups.com
        Subject: [campernicholson] Lightning Protection

         

        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

      • Graham Horne
        There is a very good section in Nigel Calders book Boatowner s Mechanical & Electrical Manual ISBN 007009618X. I find the book very practical with lots of
        Message 3 of 12 , Jul 2, 2008
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          There is a very good section in Nigel Calders book "Boatowner's
          Mechanical & Electrical Manual" ISBN 007009618X. I find the book very
          practical with lots of detail on understanding why a solution works
          with experiences of what others have tried as well. Perhaps this will
          help you.

          Regards
          Graham
          --- In campernicholson@yahoogroups.com, "Colin Campbell-Dunlop"
          <colinj@...> wrote:
          >
          > Dear Albert,
          >
          >
          >
          > My boat, Trutz #225 has lightning protection. It was originally
          built for a
          > German owner who had plans (and all the charts) for a trip down the West
          > coast of Africa. He was clearly expecting to encounter some
          thunderstorms.
          >
          >
          >
          > It sounds like a similar installation to your own. The mast is
          grounded via
          > a cable attached to the port side of the mast just above the mast heel.
          > This wire goes to a sintered metal grounding plate which is bolted
          through
          > the hull. This sits on the port side of the hull about a foot below the
          > waterline. We also have another pair of these plates stbd aft but I
          think
          > that they are to do with the disused SSB installation.
          >
          >
          >
          > I have done a bit of research on this subject and all I can say is
          that the
          > arrangement that we have on board is probably not really up to the job.
          > This isn't a problem in the UK where thunderstorms are not quite so
          regular.
          > However, for use in sub tropical or tropical areas you might want to
          talk to
          > a specialist. The problem seems to be that a really big strike
          might not be
          > properly dissipated in time leaving you with a lot of high voltage
          flying
          > around in the rigging and bouncing off of important things like
          instruments
          > and crew. Not a nice prospect. Those sintered metal plates are
          very good
          > at spreading the load though so maybe adding another one or two of
          those and
          > upgrading the cable might give some peace of mind.
          >
          >
          >
          > There are some very specialized companies out there who will no
          doubt charge
          > you a lot of money to upgrade your protection but, at the end of the
          day, it
          > seems that keeping your fingers crossed is the best policy. You
          probably
          > already know this but apparently if you can disconnect all your valuable
          > electronics and put them in the oven during a storm they will be
          protected
          > from the strike.
          >
          >
          >
          > Hope this helps in some way.
          >
          >
          >
          > All the best
          >
          >
          >
          > Colin & Jo
          >
          >
          >
          > _____
          >
          > From: campernicholson@yahoogroups.com
          > [mailto:campernicholson@yahoogroups.com] On Behalf Of Albert G. Boyce
          > Sent: 02 July 2008 03:06
          > To: campernicholson@yahoogroups.com
          > Subject: [campernicholson] Lightning Protection
          >
          >
          >
          > 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
          >
        • Graham Norbury
          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
          Message 4 of 12 , Jul 2, 2008
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            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.

            Graham

            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

          • Denece Vincent
            About eight years ago we put about a 12 X 18 inch 1/2 inch thick copper plate on the hull as close to the mast as possible. It is thru-bolted and attached by
            Message 5 of 12 , Jul 2, 2008
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              About eight years ago we put  about a 12 X 18 inch 1/2 inch thick copper plate on the hull as close to the mast as possible. It is thru-bolted and attached by a thick battery-type cable to the mast.  No strikes, yet. Thank God.
               
              Denece
               
               
              ----- Original Message -----
              Sent: 7/1/2008 10:06:25 PM
              Subject: [campernicholson] Lightning Protection

              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

            • m1fbe
              Dear Al, See http://www.strikeshield.com/ Fortunately the product has not been personally tested. Failing all else some folk wrap the inboard end of the
              Message 6 of 12 , Jul 3, 2008
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                Dear Al,

                See http://www.strikeshield.com/ Fortunately the product has not been
                personally tested.

                Failing all else some folk wrap the inboard end of the anchor chain
                round the mast and put the rest of the ground tackle over the side.

                Whatever you go for, don't forget to put essential electronics in the
                oven before the gods decide to spoil your day - especially the EPIRB.
                There is a significant chance you will need it after a strike, no
                matter what you do.


                Alan

                Montaraz
                Nic 35/16


                --- In campernicholson@yahoogroups.com, "Denece Vincent"
                <bluepearl@...> wrote:
                >
                > About eight years ago we put about a 12 X 18 inch 1/2 inch thick
                copper plate on the hull as close to the mast as possible. It is
                thru-bolted and attached by a thick battery-type cable to the mast.
                No strikes, yet. Thank God.
                >
                > Denece
                >
                >
                > ----- Original Message -----
                > From: Albert G. Boyce
                > To: campernicholson@yahoogroups.com
                > Sent: 7/1/2008 10:06:25 PM
                > Subject: [campernicholson] Lightning Protection
                >
                >
                > 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
                >
              • JIM TEIPEN
                Albert, Articles that I ve read on the topic over the years don t seem to have any real consensus on the topic. Ground plates on the bottom of the hull seem
                Message 7 of 12 , Jul 3, 2008
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                  Albert,

                  Articles that I've read on the topic over the years  don't seem to have any real consensus on the topic.  Ground plates on the bottom of the hull seem to be common,  but other sources I've read say this isn't a good idea since lightening can leave a hole at the point of exit to the water.  These articles say that its better to run a heavy conductor either from a shroud or from the mast itself directly to the water.   In the situation like you described where you were caught out in a storm, you might consider carrying a something like a heavy duty car battery jumper cable to use as a temporary ground for your mast or shroud to the water.  

                  Jim
                  Alegria
                  CN 35 - 68


                  To: campernicholson@yahoogroups.com
                  From: Albert_Boyce@...
                  Date: Tue, 1 Jul 2008 22:06:19 -0400
                  Subject: [campernicholson] Lightning Protection

                  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

                • Graham Norbury
                  Jim, There are a lot of myths and misinformation surrounding lightning protection. Fortunately the laws of physics still apply, so there are some basic
                  Message 8 of 12 , Jul 4, 2008
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                    Jim,

                    There are a lot of myths and misinformation surrounding lightning
                    protection. Fortunately the laws of physics still apply, so there are
                    some basic precautions that a vessel owner can take to maximize their
                    safety and that of the vessel. Unfortunately there isn't much that can
                    be done to protect onboard electronics as these are often damaged by
                    high voltages induced on internal wiring connected to sensitive
                    integrated circuits.

                    1. Provide a suitably sized, low resistance path to ground leading
                    directly down from the air terminal.
                    In the case of a sailboat, the air terminal is either the top of the
                    aluminum mast, or pointed rod mounted ABOVE the highest fixture (e.g.
                    vhf antenna) on the mast. ABYC standards dictate the minimum surface
                    area of an underwater grounding plate for both salt or fresh water, and
                    also the use of minimum 4 AWG conductor size to connect the air terminal
                    (base of aluminum mast) to the grounding shoe.
                    NOTE: stainless steel is a poor conductor compared to aluminum or
                    copper, so relying on your standing rigging as a primary grounding
                    conductor is likely to lead to turnbuckle or swage damage.

                    2. Provide suitably sized secondary grounding paths, to minimize side
                    flashes and crew hazard.
                    All exposed metal such as shrouds, lifelines, stanchions, binnacle,
                    pushpit & pullpit should be grounded with minimum 6 AWG sized
                    conductors, leading to the primary grounding point. In addition, metal
                    hardware such as water or fuel tanks located near the primary conductor
                    (mast base) should also be bonded to prevent side flashes.

                    3. A lightning strike delivery huge energy in a very short duration.
                    With properly sized hardware and low resistance connections, there is
                    really no reason for anything to heat up enough for damage to occur.
                    Most vessel suffering hull damage either had an inadequate ground system
                    (if at all), or defective/corroded underwater fittings that became
                    impromptu grounds.

                    While I don't have the standards book in front of me here at home, if
                    anyone wants more information, feel free to contact me directly.

                    Graham
                    ABYC Certified Marine Electrician
                    Oxford Boatyard, Oxford, MD

                    JIM TEIPEN wrote:
                    >
                    > Albert,
                    >
                    > Articles that I've read on the topic over the years don't seem to
                    > have any real consensus on the topic. Ground plates on the bottom of
                    > the hull seem to be common, but other sources I've read say this
                    > isn't a good idea since lightening can leave a hole at the point of
                    > exit to the water. These articles say that its better to run a heavy
                    > conductor either from a shroud or from the mast itself directly to the
                    > water. In the situation like you described where you were caught out
                    > in a storm, you might consider carrying a something like a heavy duty
                    > car battery jumper cable to use as a temporary ground for your mast or
                    > shroud to the water.
                    >
                    > Jim
                    > Alegria
                    > CN 35 - 68
                    >
                  • MICHAEL FORSDYKE
                    Hello Albert When Blue Days (35/209) was built, Camper and Nicholson earthed the mast to an 8 x 2.5 Dynaplate, mounted adjacent to the mast on the
                    Message 9 of 12 , Jul 5, 2008
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                      Hello Albert
                       
                      When 'Blue Days' (35/209) was built, Camper and Nicholson earthed the mast to an 8" x 2.5" Dynaplate, mounted adjacent to the mast on the starboard side. Originally they fitted a rather small wire but, at my request, replaced this with a wire of starter cable proportions.
                       
                      More recently I have fitted surge protection devices at the base of the mast in the downleads for all the masthead aerials. These are also earthed to the same Dynaplate. The devices, supplied by RS in England, are of the type used to protect commercial radio aerial installations and are suitable for most coax wires. They are rather expensive but much cheaper than replacing toasted electronics! Admittedly this does leave the wind speed/direction sensor unprotected but I have not found anything suitable for the multi-core wire from this.
                       
                      I don't claim any expertise in this field but assume that the action I have taken improves the chances of surviving a lightning strike without damage. To my knowledge the installation has not been put to the test but, should a strike ever happen, I hope the lightning will find that the earthed mast provides a better route to earth than the other masthead equipment which have a degree of inherent isolation.
                       
                      I hope this adds something useful to this interesting discussion.
                       
                      Regards,
                       
                      Michael Forsdyke
                       

                      "Albert G. Boyce" <Albert_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

                    • JOHN LARSON
                      Hi John and Gail We re heading for Passport on the 28th or 29th of July and will be around Rockland for a few days getting ready, then cruising Penobscot bay
                      Message 10 of 12 , Jul 6, 2008
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                        Hi John and Gail
                         
                        We're heading for Passport on the 28th or 29th of July and will be around Rockland for a few days getting ready, then cruising Penobscot bay also.  Lets stay in touch and try to meet somewhere, hopefully with the rest of last year's group.
                         
                        We haven't had any squeaking from the helm, but we did have a knocking noise which turned out to be worn rudder shaft packing.  We replaced the packing and the noise went away, at least so far.
                         
                        You may develop topsides envy when you see Passport, but you're bank account is likely in a lot  better shape than ours.  All that prettiness costs lots.
                         
                        Hope to see you two and the rest of the group while we're in Maine.
                         
                        John and Sandy Larson
                        s/v Passport
                      • galljj35
                        Our plans are to be in Holbrook Harbor (Castine) for 27th/28, two nights in Belfast (29/30), the 31st - thursday - in Dark Harbor on Isleboro or thereabouts
                        Message 11 of 12 , Jul 8, 2008
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                          Our plans are to be in Holbrook Harbor (Castine) for 27th/28, two
                          nights in Belfast (29/30), the 31st - thursday - in Dark Harbor on
                          Isleboro or thereabouts and in Rockland the 1 and 2nd of August.

                          From there we will probably go to Perry Creek on Vinalhaven. After
                          that we'll wander aroound, but we'll leave from Tenants/Port Clyde on
                          the 6th (at the latest) for Gloucester

                          Hope we can get catch up.

                          As to my bank account, I would rather have invested it in my hull,
                          rather than watch it evaporate as it has done in the past few
                          months !!

                          john


                          --- In campernicholson@yahoogroups.com, "JOHN LARSON" <jsl-sll@...>
                          wrote:
                          >
                          > Hi John and Gail
                          >
                          > We're heading for Passport on the 28th or 29th of July and will be
                          around Rockland for a few days getting ready, then cruising Penobscot
                          bay also. Lets stay in touch and try to meet somewhere, hopefully
                          with the rest of last year's group.
                          >
                          > We haven't had any squeaking from the helm, but we did have a
                          knocking noise which turned out to be worn rudder shaft packing. We
                          replaced the packing and the noise went away, at least so far.
                          >
                          > You may develop topsides envy when you see Passport, but you're
                          bank account is likely in a lot better shape than ours. All that
                          prettiness costs lots.
                          >
                          > Hope to see you two and the rest of the group while we're in Maine.
                          >
                          > John and Sandy Larson
                          > s/v Passport
                          >
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