Lightning Arresotr For Solar Boat

Discussion in 'OnBoard Electronics & Controls' started by ashwinnaique, Sep 25, 2015.

  1. BertKu
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    BertKu Senior Member

    Hi Gonzo, I do agree with you for radio interference's, but not for lightning. Otherwise thatched roof houses will be spun full with wires and that is not the case.

    Refer also to new regulations, special for thatched roofs. I am no longer living in Johannesburg, where the lightning is notorious high because of the 2000 meter high plateau.
    We worked with the 45 degrees principle.

    For a yacht, the angle has to be less and therefore a few wires more would compensate for that. The real problem is where the hell are we getting boat builders to use copper wires from the top of the mast to all over. You will not find anybody and I agree with them. Copper is not suitable for that technical purpose. Although Copper is 0.017 Ohm x mm2 divided by meter. For a 6 wires each 15 mm2 (parallel) from the top to 10 meter down it would be 0.017 x 15 /6 x 10 = 0.0045 Ohm or said in a different way. If a lightning strike would hit that boat with copper wires it would only create a total from top to the waterline of 200 Volt burst and not a few hundred thousand Volt. It would create a type of Faraday cage, but not for higher frequencies. Only for low frequencies.

    The lightning bursts would spread over the 6 wires and the magnetic field would be very short in view that the current can flow freely to the waterline, while in other cases it would jump and has to flow via higher resistances, which takes more time. That is the reason also that it would be more dangerous for a sailor to stand at the helm holding a metal steering wheel.

    For stainless steel I have no information and maybe somebody else can calculate that for us.

    I see that in 2013 new standards came out for lightning protection. If you have a few thousand USA Dolar, it could be yours.
    IEC 62305-SER ED. 2.0 B:2013
    Protection against lightning - ALL PARTS
    STANDARD by International Electrotechnical Commission, 01/25/2013
    Bert
     
  2. powerabout
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    powerabout Senior Member

    what I was getting at Bert was maybe you can temp rig something when on anchor or at the dock/on the hard?
     
  3. BertKu
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    BertKu Senior Member

    I am not completely with you. What do you mean with "maybe you can temp rig something when on anchor or at the dock/on the hard??" Do you mean to build something?
    Powerabout, you should borrow an earth resistance meter. Do some measurements and then you will know exactly what your problem is. One should not create something which endanger one's life. One would then think " I am protected" and then an expected lightning strike kills, Bert
     
  4. powerabout
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    powerabout Senior Member

    I meant rig a faraday cage over your boat
     
  5. BertKu
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    BertKu Senior Member

    Hi powerabout. No, I don't need it on my boat. Luckily I retired and moved to the coast, where we only have maybe twice per year a thunderstorm at the most and I am in anyway a blue water sailor. If I sail, it will only be in the bay. The highest point on my boat is my head sticking out above the cabin. No need for me to go trough the trouble. Should I ever ever encounter a thunderstorm, I will make sure , that I will be flat on the floor, doing a nice little sleep. I have been too much and often involved in lightning issues. Remember! I am retired now. Bert
     
  6. powerabout
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    powerabout Senior Member

    will a conventional digital fluke meter work at 0.01ohms to check the mast to water resistance?
     
  7. BertKu
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    BertKu Senior Member

    Very good that you try to see what your resistance actual is. Even if you do not adjust this or modify. The knowledge will help you to evaluate what could happen if you get a strike. I don't think so that you can use a fluke meter. Let me think about it and calculate whether with a simple bridge circuit, you still could do it. I have a Fluke meter and will check and come back to you. Give me a day or two. Bert
     
  8. BertKu
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    BertKu Senior Member

    O.K. I gave it a thought. Get some long insulated wires, 1,5 mm2 will do fine. About 4 meter wire which you strip the insulation for about 30 cm, which must go into the water. The second piece of wire (depends how high your mast is) you make a plan to connect it properly to the top of your mast (where you suppose to have a lightning point conductor, normally platinum or palladium for lightning trike entrance. Before you throw the wire in the water and connect the other side to the top of your mast, you put your Fluke meter on Ohms, the lowest reading you are able to have, i.e. 0-10 Ohm, or 0 -1 Ohm or 0 - 100 Ohm and you "calibrate it" by shortening the short meter leads and make a note. Then you measure the same between the one end of your wire which goes into the water and the other end which you mount onto the top. You must now plot write down what the meter tells you. Example : first 0 Ohm and second 1 Ohm. Then you throw the short end with the 30 cm bare copper in the water and connect the other end to the top of the mast. Then you switch your meter to the HIGHEST reading i.e. probably 10 MegaOhm. You should read zero. If you read infinity, your boat is not at all connected from top of the mast to the sea water. If it shows zero, you switch the knob down to lower and lower and lower level, until it gives you a reading. If it is at the lowest level, i.e. when you "calibrated" your meter, and its shows also 1 Ohm. CONGRATULATIONS, you boat is perfectly connected from top to the water line.

    If it is a higher reading, tell us, we will advise you what the consequences are. Now you investigate how that top of the mast actual is making contact downwards. via the mast or via the spreaders. Also you have to judge, if you should have a lightning strike, what would be damaged at the top. (provided you measure less than 10 Ohm, if you measure a higher reading, like everybody has said, nobody can predict what will happen.

    Looking forward to your result.
    Bert
     
    Last edited: Oct 12, 2015
  9. CDK
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    CDK retired engineer

    Just saw a short item about lightning on TV.
    A research team used a high speed camera to find out where lighting strikes and why.

    The initial strike comes from the sky and is completely random. It branches many times and generally does not reach the ground because the energy is exhausted before that happens. If after numerous attempts the ground is reached, a number of discharges uses the exact same path because the ionized air is still hot.
    Because this all happens in a split second it looks like a single discharge. Objects that we would expect to be preferred targets are ignored, even when they are very close.
     
  10. BertKu
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    BertKu Senior Member

    Hi CDK, yes it is an interesting subject. Their conclusions does not completely tie up with findings by many other research centers. Per example, they do not mention the strikes from earth to cloud. or how many times a burst can be, up to 40 in the olden days, probably with lightning lately because of more severe weather patterns, maybe more and may even exceed 50 times. Nor the severity of the currents in ampere. Like we have said before it "feels" its way to reach an object to off load their excess electrons. That could be indeed somewhere in the air which was previously otherwise having a shortage of electrons, due to friction. I prefer to stick to the findings, which concluded without no doubt, that the strike is not accidental, but to the lowest friction to offload the excess of electrons. I do agree that previously ionized air, most likely create a path for the next burst. Which explains why there are so many bursts to the same point of discharge. Like I have said before, I like to see an ionizer , which creates a potential opposite to the lightning strike by a few hundred thousand Volt. The problem is, what about the 10 % whereby the path is made easier and the strike is from earth to cloud? I will become a target. So far nobody has made a method to measure beforehand whether the potential is negative or positive and then be able to create a protection. Indeed it was a nice program and it all helps to understand lightning a little better. Bert
     
    Last edited: Oct 22, 2015
  11. powerabout
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    powerabout Senior Member

    thanks for all that but Carbon rig, fittings all glued on
    Maybe I need to talk to a mast builder?
     
  12. BertKu
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    BertKu Senior Member

    Hi Powerabout, what you are saying is, that your resistance is infinity.

    Look there are two philosophies.

    1) When I am lucky, the lightning strike will not hit my boat , because I believe in mysteries and scriptwriters who like to put some punchlines to make my script nicer.
    and the other one is:
    2) I believe in logic, in calculations, in probabilities:very likely or not, I can calculate and then make a decision, whether the circumstances could be against me.

    You have to make a decision:
    You have a 5 to 7 meter carbon fiber mast, with stainless steel wires going from top downwards, what is my likelihood, that a lightning strike regards my mast a nice shortcut to reach and offload my excess electrons to earth/Sea, by jumping the last few centimeters from mast to sea or through
    the hull to the sea via impurities. If the answer is, I am happy and confident. That is fine. If your answer is . No, I need to speak to my boat builder.

    Ask him to put in writing that my boat is a safe, during a lightning strike with a 7 meter carbon conducting mast not conducting to the seawater. He will never do that. But if you ask an electrical engineer to put in writing what your probabilities is, when getting a lightning strike , whether your boat is safe, he will do calculations. Like any mechanical engineer is doing calculations whether a roof is strong enough to withstand strong wind forces. Don't speak to a boat builder, speak to the professor in electronics/electrical at a university and put your question forward to him. That would be my advice. Bert
     
  13. powerabout
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    powerabout Senior Member

    Hi Bert

    what I am trying to get at is how do you make a decent connection to a carbon mast?
    surface will be epoxy plus 2 pack clear plus 1 pak varnish over that

    Should the manufacturers be embedding a wire mesh in them to you can actually get a connection from top to bottom?

    Rigging may be synthetic as well or carbon

    what to do?
    regards
     
  14. BertKu
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    BertKu Senior Member

    I am not a boat builder and can only give you my opinion what I would do. I would run 2 thick copper wires at least 8 mm2 along the 2 side spreaders to the side of the boat and then with a metal plate into the water on both sides. Should my boat heel, at least it makes proper contact with the water. Secondly I would go the the churches and ask various priests/etc. who the architect and builder was for their church towers and obtain a platinum peak for the top of my mast from their suppliers or would search in the internet. Maybe you could also use gold or palladium. Yes, it is expensive. The thickness of the wire, CDK had some excellent advise in one of the threads, just search for it. Or you could approach Gonzo, who does inspections for insurance companies and ask him what the specifications are for your kind of mast. Alternative there are some very good boat builders on this website, who could give some good advise, PAR per example. Bert
     

  15. BertKu
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    BertKu Senior Member

    Powerabout, here some websites and my comment.
    Special look at the church, which did not have a lightning protection, what that tower did, it absorbed the energy and then exploded, while you MUST conduct, divert and reroute the current. In that case your energy is very low and does no harm your boat. But if you have a spike, (with the copper wires) at the same level as your top of the carbon mast, I cannot give you any guarantee that the lightning strike also not start rolling down your carbon mast and then discover, hay, ??? it stops and then jumps sideways to whatever is then a path.
    But if you have the spike with the copper wire higher than your carbon mast and that copper wire is at the end connect to seawater, there is no real reason for the lightning surge to split and also go down via your carbon mast. Everything in life is logic said Einstein in the church in Rotterdam some 65 years ago, when he was brilliantly playing the church organ. I never forgot about that statement. As long we can understand the logic, then the solutions are simple.

    http://www.jlsteelstructure.com/en/productinfor.php?id=185&sid=363&PNAME_Lightning_tower
    They are building special towers for creating a easier downpath for lightning. However, they don’t say whether they use a fat thick copper wire downwards. Maybe you should ask them.
    http://www.dailymail.co.uk/news/art...s-tower-knocking-masonry-flying-building.html Thery did not have a lightning protection
    http://stormhighway.com/lightning_split_strike_more_than_one_place.php What the CSIR did some 40 years ago was the same, with the diffrenece that they build spikes on the mat floor to see, whether the lightning would go the easier way or just at random. Their findings was, it went via the special platinum peak to earth, all the time.
    Structural Protection
    STRUCTURAL PROTECTION
    The main and most effective measure for protection of structures against physical damage is considered to be the lightning protection system. A lightning protection system consists of both an external and an internal lightning protection system.
    Current Standards Quinquennial reports may state that the lightning protection system does not meet the recommendations of BS EN 62305: 2011. This British Standard is the nationally accepted way to deal with the potential for lightning strikes, and is referenced in the legal guidance documentation for safety applied to electrical systems.
    http://www-public.tnb.com/eel/docs/furse/BS_EN_IEC_62305_standard_series.pdf
     
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