Page 2 of 3 FirstFirst 123 LastLast
Results 36 to 70 of 89

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

  1. #36
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    See post #15

  2. #37
    Join Date
    Apr 1999
    Location
    Hyannis, MA, USA
    Posts
    45,676

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    In the day before the gauss cage approach, I had a number of boats where the butt of the mast was wired to the top of a keel bolt and that keel bolt had, instead of the normal pocket, a connection to a ground plate.

    It's a good theory in the sense of straight line down to ground. Bad in that ground dissapation is better near the surface, and in that it allows for side flashing inside the boat.

  3. #38
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    It would be very hard to offer a path with less resistance then a big aluminum mast to act as an umbrella. Electricity at these voltages doesn't make turns very well either.

  4. #39
    Join Date
    May 2016
    Location
    Ottawa, Canada
    Posts
    190

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Navydog - If you google you'll get lots of hits. The general accepted statistic is that each commercial aircraft gets struck once per year. Ground is just a reference point - it's really about the voltage potential between the entry and exit points. Like "small boats rock" noted, it's pretty much sorted in other areas like buildings, aircraft.

    Look, I get it, the mitigation for lightening might be difficult to implement or might cause other issues to a wooden boat owner. What I don't get are the comments like it's an unknown science, which seems like a way to justify whatever choices are made.

    Cheers,
    Mark

  5. #40
    Join Date
    Jan 2007
    Location
    North Shore, Massachusetts
    Posts
    8,636

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    how about a copper wire on a sick that could be raised like a topmast and the other end of the wire in the water... or maybe 3 wires... also my mast folds so lower profile...

  6. #41
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Mark0 View Post
    Navydog - If you google you'll get lots of hits. The general accepted statistic is that each commercial aircraft gets struck once per year. Ground is just a reference point - it's really about the voltage potential between the entry and exit points. Like "small boats rock" noted, it's pretty much sorted in other areas like buildings, aircraft.

    Look, I get it, the mitigation for lightening might be difficult to implement or might cause other issues to a wooden boat owner. What I don't get are the comments like it's an unknown science, which seems like a way to justify whatever choices are made.

    Cheers,
    Mark
    I posted a link to the NFPA code which is very clear (If you can read codes) how to protect a vessel. The problem absolutely is retrofitting a boat up to code. Main conductors for copper are bare 1/4" and 1/2" for aluminum. Who wants a big cable running across their boat or down the rigging? Bringing the conductor into the cabin is a bad idea.

    So even though the science is developed the physical application and equipment is not.

    The code calls for a 1ft sq. grounding plate or the aggregate. But it doesn't specify the methodology of mounting. How is this done without causing damage to the hull if there is a strike?
    Last edited by navydog; 07-12-2018 at 06:07 AM.

  7. #42
    Join Date
    Aug 2017
    Location
    Melb, Vic, Aus
    Posts
    289

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Small boats rock View Post
    When it comes to small boats and lightening protection there are many views and not much agreement. However, look to protection on buildings and we see lightening protection pretty much sorted. High rise buildings get hit often, and the occupants will not even be aware. So, I ignored all the small boat commentary, read all I could about systems used for buildings, then applied that information to my boat. In essence the message for buildings seems to be, really heavy duty conductor (eg. copper cable) and big ground (plate, or mesh buried in the soil), and at the skyward end is a spike or sphere (both seem to work fine).
    I will anchor next to you bro. To my reasoning that just screams "hit me". So if I anchor next to you I should be safe

  8. #43
    Join Date
    Apr 1999
    Location
    Hyannis, MA, USA
    Posts
    45,676

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    The ground plate is simply screwed to the hull. The square foot requirement is actually outdated given scientific understanding. There is discharge over the surface area of the plate but most discharge funnels over the sharp edges where the surface meets the thin edge. For this reason, the plate is not streamlined, not recessed into the hull. A one foot square plate has four feet of sharp edge exposed to the water. A one half by two foot plate has five.

    Grounding plates a half foot or so below the surface appear to work better than bottom of the keel plates.

    The height of the mast matters less than many think. Not all lightning is formed in the classic 'thunderhead' cumulonimbus cloud but most ground or ocean surface strikes do. The bottom of the cloud can be lower than a thousand feet and as high as ten thousand feet. The top can rise to over seventy thousand feet. The lightning forms in the middle half of the cloud, more or less. It's not in one place and depends upon the charge at the surface as well but mainly, if you think of lightning as involving stuff happening at thirty thousand feet or more, you'll see that a forty or fifty foot mast does not offer such an improved route to ground that it can "pull the lightening" very far.

    I was once entering a harbor in a thunder squall when lightening struck the jetty, which was only about six feet above the water and had no structures where it struck, about a hundred feet off my beam. The lightning struck there rather than my boat or the light tower at the end of the jetty, perhaps four hundred feet astern of us at the moment.

    I've a friend who has a dock at home. He keeps his sloop on that dock. There are tall trees along the shore and his house (with lightening rods) is a bit uphill and taller than his boat's mast. The boat has been hit twice at that dock. The house never.

    High points on land often seem to attract lightening because they also contribute to how the clouds are formed and how the ground charge for lightening is formed. Some are quite reliable. Lightening squalls rolling along would give visually grand repeated hits on the lightning system on an across the valley neighbor's silo. My point is simply that there's a great deal more to the path than height.

    There is nothing you can do to prevent a lightening strike. You can only give it a safe path when you are struck.

    Being the shortest mast in the anchorage is not a reliable prophylactic.

    G'luck

  9. #44
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    "The ground plate is simply screwed to the hull. The square foot requirement is actually outdated given scientific understanding. There is discharge over the surface area of the plate but most discharge funnels over the sharp edges where the surface meets the thin edge. For this reason, the plate is not streamlined, not recessed into the hull. A one foot square plate has four feet of sharp edge exposed to the water. A one half by two foot plate has five."

    The 12" sq is a area measurement not really having to do with shape.

    But this is my point and the code is for all boats. Nothing is specified for mounting. If you have a glass boat you have to bolt it on.

    So then a cable is run down the side of the boat, or do you run it inside and through the hull. Even a flat strap is going to look fugly no matter where is is placed.

  10. #45
    Join Date
    Jan 2005
    Location
    Deepest Darkest Wales
    Posts
    19,838

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Faraday cage ???

    Baffled by the "lead doesn't do much as a ground" remark, I've used lead to dump thousand amp currents into water and it worked fine for many years.
    Creationists aren't mad - they're possessed of demons.

  11. #46
    Join Date
    Feb 2004
    Location
    Texas
    Posts
    10,281

    Default

    Quote Originally Posted by Mark0 View Post
    No. It's a crap shoot if you get hit or not, but when you do get hit it's well understood and the risk can be mitigated.

    Cheers,
    Mark
    Yea, that's why lightning protection theories change every ten years or so.

  12. #47
    Join Date
    Apr 1999
    Location
    Hyannis, MA, USA
    Posts
    45,676

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    I did not know of any changes. Fifty years ago I learned of both the single pole and the gauss cage models and how to choose. Are you a building that's tall or a big and square? Are you an automobile? Are you a boat? Are you an airplane? All some variation of the two basics.

    There have been evolutionary changes in material standards and specifications.

    As is that fantastic lightning show at our local museum of science.


  13. #48
    Join Date
    Feb 2004
    Location
    Texas
    Posts
    10,281

    Default

    Quote Originally Posted by navydog View Post
    How many airplanes get hit? How does one ground an airplane? Show us some real numbers of airplane lightning strikes. You totally ignore the quote I posted btw.
    Oh, airplanes get hit a lot. I read once, in scientific ametican, that the average commercial jet takes a hit at least once a year. But modern planes, in the air, have a huge advantage. The skin and frame is all metal, and they are in the air, not grounded. So when they get hit, the current goes from entry point on the plane to exit point (IIRC typically on the wing and on the fuselage respectively), and the may thing that has to happen is keep all the systems well isolated from the skin. Ok, easier said than done, but that's due to the complexity of the craft, not the complexity of the problem.

    So the plane analogy to boats does not seem valid to me, but not because it's rare. Lightning is easier to understand on a plane. And the theory behind damage prevention is better understood, better studied, better tested, etc.

  14. #49
    Join Date
    Feb 2004
    Location
    Texas
    Posts
    10,281

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    I have been an advocate for dyneema rigging since changing over to it on my current boat. It simply has so many things going for it, I do not understand using steel rope on almost any new boat. But I will admit, the lightning protection issue is the one issue. On my current boat, a 29 ft sloop with fractional rig, I do not worry about it, as it is used extensively for day sailing. If lightning hits it, it will likely be in the marina, but it is not the tallest mast, so I cross my fingers. I removed the lightning protection cable from the chain plates to the keel bolt when I switched the rigging. On my next boat, I have not yet what to do. Wooden mast, gaff rig. I will use dyneema rigging (either Colligo Dux or New England STS), but I am stumped about the lightning protection. I am leaning towards going through the mast, I had not really considered the problem of splinters flying about if the mast happens to explode. I will continue to ponder the issue. Note, I have never liked the idea of a large plate under the hull, would much rather run it through a keel bolt and hope for the best as far as the lead grounding is concerned.

  15. #50
    Join Date
    May 2016
    Location
    Ottawa, Canada
    Posts
    190

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by peb View Post
    Yea, that's why lightning protection theories change every ten years or so.
    Not for mitigation of a strike when it occurs. The "protection" theories change, yet this is probably more of a marketing tool. Most other industries have understood for a long time it's not really possible to divert a potential strike.

    Cheers,
    Mark

  16. #51
    Join Date
    May 2016
    Location
    Ottawa, Canada
    Posts
    190

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by peb View Post
    Oh, airplanes get hit a lot. I read once, in scientific ametican, that the average commercial jet takes a hit at least once a year. But modern planes, in the air, have a huge advantage. The skin and frame is all metal, and they are in the air, not grounded. So when they get hit, the current goes from entry point on the plane to exit point (IIRC typically on the wing and on the fuselage respectively), and the may thing that has to happen is keep all the systems well isolated from the skin. Ok, easier said than done, but that's due to the complexity of the craft, not the complexity of the problem.

    So the plane analogy to boats does not seem valid to me, but not because it's rare. Lightning is easier to understand on a plane. And the theory behind damage prevention is better understood, better studied, better tested, etc.
    Lightening strikes are current flowing into and out of a structure. If one is sitting at ground potential or not is irrelevant. Ground is just a reference.

    Like I pointed out above, yea, it's hard to do on a wooden boat - but that doesn't mean it's not understood what works and what doesn't.

    Mark

  17. #52
    Join Date
    Oct 2009
    Location
    South Puget Sound/summer Eastern carib./winter
    Posts
    15,311

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Mark ,
    We are like the opposite as can be on this.
    You seem to trust the science/engineering /outcome of a strike on a boat like an accurate GPS position '
    I 'm more like, the outcome of a strike at sea is like a sextant sun shot... within 10 miles is a gift!
    bruce

  18. #53
    Join Date
    Sep 2004
    Location
    Munich, Germany
    Posts
    213

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Thnk you guys, interesting discussion. Thank you also for the reference to the literature.

    May I try to summarize the advice:

    1. Lightning protection is not avoidance of being struck by lightning, but avoiding the damage when beeing struck
    2. The air terminal of the lightnig rod must be the highest point of the boat (-> radio antenna must be lower!)
    3. We need a solid, beefy conducting connection from this air terminal to a current discharger. This can be an aluminium mast. In case of a wooden mast a thick copper rod running along the mast is a solution.
    My questions here are:
    Can this rod run inside the mast?
    Can I use a copper rod or copper band/webbing running along a dyneema stay instead of the rod along the mast?
    Can I connect the lightning rod at the mast top to the stainless standing rigging (SS shrouds / stays) instead of having a cupper rod along the mast down?
    4. The current discharger may be a unsheeted, metallic keel, but sleek discharging plates with sharp edges mounted external to the boat at waterlevel height seam to work better.
    5. Connection of additional, boat circumferential current conducting structures (e.g. metallic life lines) to the current discharger forms a Faraday cage and enhanced the level of protection for people and electrical system
    6. Surge-protective devices (SPD) or transient voltage surge suppressors (TVSS) should be installed to protect the boat electronics.

    So it seems the lightning protection concept by itself is simple, but integrating into a wooden boat with a wooden mast, dyneema standing rigging and no possibility to run an lightnig rod outside the mast is tricky. Possbile "solutions" may be:

    Solution 1: All SS standing rigging connected to the lightning rod in the top mast, and avoiding so the rod along the mast. Possible?
    Solution 2: At least one SS stay connected to the lightnig rodin the top mast, and avoiding so the rod along the mast. Good enough?
    Solution 3: All dyneema rigging and a mast internal lightnig rod. Is this a solution at all? Can this arrangement survive a struck of lightnig?

    Dyneema life lines would further weaken the situation, as no Frarday cage could be formed.

    < Head scratching >. Me thinks, this is the end of the dyneema dream.
    Last edited by zauberberg; 07-13-2018 at 04:10 AM.
    Thomas
    -----------------------------------
    panta rei

  19. #54
    Join Date
    May 2016
    Location
    Ottawa, Canada
    Posts
    190

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by wizbang 13 View Post
    Mark ,
    We are like the opposite as can be on this.
    You seem to trust the science/engineering /outcome of a strike on a boat like an accurate GPS position '
    I 'm more like, the outcome of a strike at sea is like a sextant sun shot... within 10 miles is a gift!
    bruce
    I don't think we are that far off then. If you believe in the math and engineering behind the sextant, it's the same for lightening protection.
    However I think you would be terrified I'm using white oak on my boat !

    Mark

  20. #55
    Join Date
    Apr 1999
    Location
    Hyannis, MA, USA
    Posts
    45,676

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    While more concerned that terrified, most of us would feel that way were you framing with red oak.

  21. #56
    Join Date
    Jul 2017
    Location
    Toodyay, Western Australia
    Posts
    694

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Geftb View Post
    I will anchor next to you bro. To my reasoning that just screams "hit me". So if I anchor next to you I should be safe
    You may be right, and I guess this is what it comes down to, that in the end every person must distill lots of information and advice, seemingly conflicting at times, to arrive at a decision which the are willing to live with. In my case I've found myself sailing through lightning storms often enough to feel that a strike is inevitable sooner or later, so my choices are based on that assumption as a starting point.

  22. #57
    Join Date
    Feb 2007
    Location
    Blue Hill, ME
    Posts
    972

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    A bit OT, I've never been hit by lightning while boating but many times in my aviation career. It always gets you attention but nothing catastrophic Typically a few CB's pop, sometimes losing a radio or navaid, scorched rivets on the skin mark the ingress. Once while crossing the pond in the 747 we got a good strike and a dome light cover bounced off my head. That gets your attention! It also blew out the HF antennas, which added 2 hours to the return crew's flight. .

    Just last week we saw a bolt hit our garden fence about 100' away, sparks were flying. Unfortunately it also burned out our generator, TV, computer, modems. Got lucky in the workshop, it blew the bandsaw plug out of the socket, destroyed the cover plate sending pieces across shop, but amazingly all tools have checked out fine. Lighting does have a "mind" of it's own
    Steve B
    Sjogin IIIa
    PAYTON 13' Pea Pod

    RIVUS 16' Melonseed


    "If a man must be obsessed by something, I suppose a boat is as good as anything, perhaps a bit better than most." E. B. White

  23. #58
    Join Date
    Apr 2000
    Location
    Barrie, Ontario, Canada
    Posts
    4,853

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    A boat to a thunderstorm is like an ant to an elephant.

    Drake is 70 years old, wood, with no lightning protection, always in waters that see frequent lightning in season. No strikes.

    My strategy is to anchor or sail near boats with tall metal masts. I've no evidence that this works, but it makes me feel better

    Of course, the real danger from a t-storm is not the lightning.

  24. #59
    Join Date
    Jan 2007
    Location
    North Shore, Massachusetts
    Posts
    8,636

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by SBrookman View Post
    A bit OT, I've never been hit by lightning while boating but many times in my aviation career. It always gets you attention but nothing catastrophic Typically a few CB's pop, sometimes losing a radio or navaid, scorched rivets on the skin mark the ingress. Once while crossing the pond in the 747 we got a good strike and a dome light cover bounced off my head. That gets your attention! It also blew out the HF antennas, which added 2 hours to the return crew's flight. .

    Just last week we saw a bolt hit our garden fence about 100' away, sparks were flying. Unfortunately it also burned out our generator, TV, computer, modems. Got lucky in the workshop, it blew the bandsaw plug out of the socket, destroyed the cover plate sending pieces across shop, but amazingly all tools have checked out fine. Lighting does have a "mind" of it's own




    Quote Originally Posted by Dave Hadfield View Post
    A boat to a thunderstorm is like an ant to an elephant.

    Drake is 70 years old, wood, with no lightning protection, always in waters that see frequent lightning in season. No strikes.

    My strategy is to anchor or sail near boats with tall metal masts. I've no evidence that this works, but it makes me feel better

    Of course, the real danger from a t-storm is not the lightning.
    ! +1

    when a thunder thumper rolls off the continent we've got much bigger problems than lightning flashes on our minds.

  25. #60
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    This will be my solution; attach a bonding cable to the back stay strap bolts inside the transom to the rudder post. Then bond the rudder post to straps attached to each side of the rudder. Hopefully lightning would follow the path and not go down the mast.

  26. #61
    Join Date
    Oct 2009
    Location
    South Puget Sound/summer Eastern carib./winter
    Posts
    15,311

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    I used to keep a coil of heavy copper wire , one end hose clamped to a mizzen shroud, the other end hose clamped to an 18 inch long X 2 inch dia bronze pipe.
    Mostly, it stayed coiled up in the cockpit dodger pocket. I 'd pitch it over when I felt a certain tingle. Underway , usually.
    Ugly messy clumsy thing .
    That was when I was in central america/new england....hardly any lightning in the eastern caribbean or the pnw.
    ...aaaand I'd un plug my junk, depending on the severity... sometimes dis connecting the battery cables.

  27. #62
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    There are T storms every week on the Chesapeake. Eventually one will be inescapable even though you can see them coming and you make it into an anchorage. It still requires sitting through it.

  28. #63
    Join Date
    Feb 2006
    Location
    Pennsylvania
    Posts
    8,185

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Used to have a boat in a slip on the Chesapeake. It had a bottle brush type arrester on the masthead. One day we went to the boat and the brush looked a bit fried. Another time, later, we went and it was gone. I went up the mast to find a melted blob of metal on the bracket. Remarkably, no damage to the electronics, even the radio antenna up there was fine. On that boat, the aluminum mast was grounded to a diesel saildrive leg. Seemed to work.
    -Dave

  29. #64
    Join Date
    Apr 2010
    Location
    South Australia and Tasmania
    Posts
    15,740

    Default

    My ketch has a copper strip inside each mast. Bolted to Keel bolts. Been that way for 45?years. I don't know if she's ever been hit by lightning. I do know the masts have never exploded.


    Sent from my iPhone using Tapatalk

  30. #65
    Join Date
    Apr 2000
    Location
    Barrie, Ontario, Canada
    Posts
    4,853

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by SBrookman View Post
    A bit OT, I've never been hit by lightning while boating but many times in my aviation career. It always gets you attention but nothing catastrophic Typically a few CB's pop, sometimes losing a radio or navaid, scorched rivets on the skin mark the ingress. Once while crossing the pond in the 747 we got a good strike and a dome light cover bounced off my head. That gets your attention! It also blew out the HF antennas, which added 2 hours to the return crew's flight. .

    Just last week we saw a bolt hit our garden fence about 100' away, sparks were flying. Unfortunately it also burned out our generator, TV, computer, modems. Got lucky in the workshop, it blew the bandsaw plug out of the socket, destroyed the cover plate sending pieces across shop, but amazingly all tools have checked out fine. Lighting does have a "mind" of it's own
    Me too, in airliners a few times. Always a bit startling.

    You never knew where it was going to enter, or exit...

  31. #66
    Join Date
    Aug 2017
    Location
    Melb, Vic, Aus
    Posts
    289

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Small boats rock View Post
    You may be right, and I guess this is what it comes down to, that in the end every person must distill lots of information and advice, seemingly conflicting at times, to arrive at a decision which the are willing to live with. In my case I've found myself sailing through lightning storms often enough to feel that a strike is inevitable sooner or later, so my choices are based on that assumption as a starting point.
    I understand that for sure. It all come down to what your happy to live with.

  32. #67
    Join Date
    Sep 2004
    Location
    Munich, Germany
    Posts
    213

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Phil Y View Post
    My ketch has a copper strip inside each mast. Bolted to Keel bolts. Been that way for 45?years. I don't know if she's ever been hit by lightning. I do know the masts have never exploded.


    Sent from my iPhone using Tapatalk
    Wooden masts? SS standing rigging?
    Thomas
    -----------------------------------
    panta rei

  33. #68
    Join Date
    Apr 2010
    Location
    South Australia and Tasmania
    Posts
    15,740

    Default

    Quote Originally Posted by zauberberg View Post
    Wooden masts? SS standing rigging?


    Precisely


    Sent from my iPhone using Tapatalk

  34. #69
    Join Date
    Sep 2007
    Posts
    1,137

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by Dave Hadfield View Post
    Me too, in airliners a few times. Always a bit startling.

    You never knew where it was going to enter, or exit...
    Being on a boat struck by lightning won't be anything like being on a 747. Particularly if for some unexplainable reason the sailor is on deck.

  35. #70
    Join Date
    Jul 2011
    Location
    Lindstrom, MN
    Posts
    2,240

    Default Re: Lightning protection for a wooden boat with dyneema standing rigging

    Quote Originally Posted by navydog View Post
    How many airplanes get hit? How does one ground an airplane? Show us some real numbers of airplane lightning strikes.
    I am not arguing with navydog. Just answering the question.

    On average, all commercial airplanes get hit by lightning more than once every year.
    The last confirmed commercial plane crash in the U.S. directly attributed to lightning occurred in 1967, when lightning caused a catastrophic fuel tank explosion.
    https://www.scientificamerican.com/a...-when-lightni/

    Aircraft have to be designed to survive a lightning strike. As Bruce said, the comparison is indeed apples and oranges. The strength of the strike on an aircraft is limited by the capacitance (size) of the aircraft. This is not a guess. I did have to look into this for a system that we were designing to be mounted on an airplane. The strength of a lightning strike on the ground or water is limited by the size of the storm. If not apples and oranges, firecrackers and nukes. TITTB?
    Electrolytic damage to the wood under a grounding plate is a very real concern. I have seen boats that required several new planks due to severe deterioration under a copper plate. This gets worse when you mix stainless wire, aluminum spars, bronze fasteners, lead keels, copper connecting wire....

    I have cast iron ballast, and am loathe to connect heavy copper wire to my keel bolts. Perhaps a large knife switch that is closed only when on board and otherwise left open could isolate the system enough.
    Under the grounding plate is a problem area.

    Galvanic corrosion can not take place if the metal of concern is not in contact with the water. None of the metals above water and not embedded in salt water saturated wood are subject to galvanic corrosion except in the immediate area of a dissimilar metal faying surface. One notable exception is an aluminum surface that is located where water dripping off of a copper alloy lands on the aluminum. The aluminum can reduce copper ions to copper metal and that will result in galvanic corrosion.

    The condition under which a copper wire connected to a keel bolt can cause galvanic corrosion is in a flooded bilge. If the bilge is going to have standing water, the frequently submerged portion of the wire can be insulated and the connection can be sealed.
    Last edited by MN Dave; 07-15-2018 at 11:32 PM.
    Management is the art of counting beans. Leadership is the art of making every being count. --Joe Finch

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •