Electrical grounding questions

Discussion in 'Sailboats' started by wesley Sherman, Dec 13, 2020.

  1. wesley Sherman
    Joined: Jan 2020
    Posts: 77
    Likes: 10, Points: 8
    Location: New York

    wesley Sherman Junior Member

    I purchased an Alberg 30 couple of years ago and doing a complete gut and refit. I have all the major bulkheads in and tabbed and working on placing some fiberglass conduits to run wires.

    Now the boat I purchased from the previous owner may have had some extensive electrical experience am guessing, due to the absolutely beautiful wiring that was in this boat. Very detailed and precise. Obvious ly some pride in personal work or whoever did it did a sweet job. I did hear however that He did is own work.

    Anway I removed it appears to be a large copper plate approx 1/8 thick heavy epoxied to the hull by the forefoot cutaway. Plate was 14"x 14". Insider the boat was a grounding bar. The wires 1/0 and 2 were 3/0. They were non-Tin Plated large wire twisted strand heavy as hell and hard to bend. The 3/0 went through the deck through a heavy rubber grommet to the base of the mast. Rest went to things like the rudder stock, engine, electrical panel, 1/0 ran to the radar mount on the mast, another ran to the railing aft of the boat. last one to the fuel tank that had a rod extending from the base plate that was aluminum that the tank was on suspended by 1" rubber grommets.
    The plate was actually slightly off the hull around the edges, being held away from the hull by the epoxy. It looks intentional the gap off the boat was uniform all the way around. Also, the outer edges of the plate were uneven and look like being eroded away and discolored, and pitted, not a smooth edge. lastly, there was a badly deteriorated disk attached to the plate that looked like a zinc disk. There is also a bonding plate that had tined wire running to all thru-hulls, all this seemed to be connected to the plate outside and the zinc attached to it.

    I read a bit from the open topic on the internet and have come to no conclusion about if to replace this or not. Does it work or is it just a hopeful piece of mind. In much reading, there is no consensus as to if grounding would work for lightning strikes on the mast. So I am assuming if not for lighting strike this was a bonding system and lighting strike setup? I don't get how more masts are not hit stats say 3 monohulls per 1000 seems crazy.

    The previous owner seems to have a precise way of everything he placed.. She was in a bad state due to years of sitting but you could see a little about the person that was there before me. Precise organized, extra parts extra tools thought out tools and parts not just mash of crap. Even the surveyor that came out said despite the outward showing of the boat, dirt lichen leaves etc. The boat was in better shape than most he had seen.

    Ideas are appreciated.
     
    Last edited: Dec 13, 2020
  2. jehardiman
    Joined: Aug 2004
    Posts: 3,033
    Likes: 546, Points: 113, Legacy Rep: 2040
    Location: Port Orchard, Washington, USA

    jehardiman Senior Member

    fallguy likes this.
  3. missinginaction
    Joined: Aug 2007
    Posts: 1,054
    Likes: 225, Points: 63, Legacy Rep: 512
    Location: New York

    missinginaction Senior Member

    You say the plate was at "the forefoot cutaway". Pretty much directly under the mast? What I'm getting at is the idea that the 000 AWG wire coming down from the mast was in a direct, or almost direct line with the copper plate that was located at the forefoot cutaway. If so, that's lightning protection. Sounds like the previous owner used some lighter gauge wire to add some additional protection for the radar and rails and then decided to ground his fuel tank (diesel?) to the grounding busbar.

    Volumes have been written on lightening protection. The best writing I've seen is in Nigel Calders "Boat Owners Mechanical and Electrical Manual". Read chapter five.

    https://www.amazon.com/Boatowners-M...p-0071790330/dp/0071790330/ref=dp_ob_title_bk

    Sounds like the previous owner did you some favors.

    MIA
     
  4. wesley Sherman
    Joined: Jan 2020
    Posts: 77
    Likes: 10, Points: 8
    Location: New York

    wesley Sherman Junior Member

    I was going to mention, when I was a yout (6-15) I sailed long voyages with my father (wish I would have learned more) I was partially homeschooled. We first started sailing in an Alberg 30 Hull number I don't know. Be curious who has it now. It was not new at the time it was purchased from someone that purchased it and then had to sell it is all I know. In 1975 or 76 my dad purchased a Gulfstar 50 and we spent most of our time in that. But my love of sailing came from the Alberg. We sailed that boat till 1982 when I went off to officers school in the Army. But my point was that my father when a big storm was coming would connect a very large coated cable, I remember maybe it was 1-2" thick to the base of the mast and threw it overboard, Maybe 20 feet long, I know it was so heavy (I was young, didn't come out more than once or twice). I remember he said it was for a lighting strike, said it might send the power shortest easiest route to the ocean.
    Then he would sit me below in the cabin, this he said was the safe zone from a lighting strike, He called it a cone zone of safety. I cant find much on this online or at all about cables overboard etc.. But just a short story of his way if it was real or not who knows, as we never got hit. We saw the lighting hit the ocean once not far away and the light radiated in the ocean around the strike for a sec. Hell, I is was scared because Dad's hair and mine stood up prior to and after the hit. True story, this is why I want to get it as right as I can even if it only helps a little.
     
  5. wesley Sherman
    Joined: Jan 2020
    Posts: 77
    Likes: 10, Points: 8
    Location: New York

    wesley Sherman Junior Member

    Thanks " missinginaction" I am glad that is recommended reading as it is on order as we speak. Found that a few days ago and saw a few recommendations for it too.
     
  6. rangebowdrie
    Joined: Nov 2009
    Posts: 102
    Likes: 38, Points: 28, Legacy Rep: 10
    Location: Oregon

    rangebowdrie Senior Member

    On mine own boat the mast/heel fitting is ~6in. away from a keel bolt for the outside ballast.
    I've used heavy batt cable and bolts to have an "air gap" of ~1/4 in.
    That way the mast is not electrically connected to anything, but in the event of a strike, the air will ionize in the gap and conduct directly into the outside lead.
     
  7. wesley Sherman
    Joined: Jan 2020
    Posts: 77
    Likes: 10, Points: 8
    Location: New York

    wesley Sherman Junior Member

    So a spark plug takes about 4000v dc to jump a 2.5 spark plug gap. Takes about 76000-volt dc to jump an inch. I learned this from classes from working as a controller at a DAM. I believe a bolt of lightning can carry as much as 3 million + volts at theory around up to 100.000 to 200000 ampers. It has traveled miles to the earth I would be interested in how or why this would work over a small gap to reduce any damage.
    But I could be way off base as well.
    Thanks
     
    Last edited: Dec 13, 2020
  8. rangebowdrie
    Joined: Nov 2009
    Posts: 102
    Likes: 38, Points: 28, Legacy Rep: 10
    Location: Oregon

    rangebowdrie Senior Member

    I can't speak to the scientific knowledge about that.
    I did what I did because of some stuff I read about lighting strikes about 30 years ago,, perhaps the knowledge base now has a different take on the subject?
    One thing for sure, you really don't want the strike to come down a mast and jump to a seacock in its mad dash to water, or travel thru a bonding system or thru the engine>transmission>shaft>water.
     
  9. wesley Sherman
    Joined: Jan 2020
    Posts: 77
    Likes: 10, Points: 8
    Location: New York

    wesley Sherman Junior Member

    Rangebowdrie you are so right, That is a big fear in some ways a hole blown open in a boat is never a good thing. I get the feeling that you can only do so much to protect yourself from a strike and other than basic bonding it's luck of the draw.
     
  10. fallguy
    Joined: Dec 2016
    Posts: 4,946
    Likes: 901, Points: 123, Legacy Rep: 10
    Location: usa

    fallguy Senior Member

    Why did you remove the lightning ground? I'd have left it in.
     
  11. Ike
    Joined: Apr 2006
    Posts: 2,524
    Likes: 361, Points: 83, Legacy Rep: 1669
    Location: Washington

    Ike Senior Member

    The installation as described is basically what is recommended by the American Boat and Yacht Council, and by knowledgeable authorities on lightning protection.
    Here are some links to sites that discuss lightning protection
    The Science Of Lightning Protection http://www.marinelightning.com/science.htm
    Non-technical Article on lightning protection http://www.marinelightning.com/
    Information/GroundingGuide.htm
    Technical Lightning Grounding Information http://www.marinelightning.com/
    Information/GroundingConcepts.htm
    A New Concept for Lightning Protection of Boats http://www.marinelightning.com/
    EXCHANGEOct2007Final.pdf

    L-36.com A collection of articles on lightning protection http://l-36.com/lightning.php
    Michael Kasten on Lightning Protection http://www.kastenmarine.com/Lightning.htm
    NASD on Lightning http://nasdonline.

    I agree with Fallguy. Leave the connection to lightning ground. It's there for protection,
     
  12. philSweet
    Joined: May 2008
    Posts: 2,459
    Likes: 268, Points: 83, Legacy Rep: 1082
    Location: Beaufort, SC and H'ville, NC

    philSweet Senior Member

    And they work. The Florida Keys has one of the highest ground strike densities on the planet. Up to 1000 ground strikes per sq mile per year. Be sure to secure those wires really well. There can be hundreds of pounds of force on them when conducting a surge.

    @ rangebowdrie Air gap ESAs are a thing. You can buy them. You don't want an exposed airgap, the EMP will fry everything. ESAs are designed so that once the arc starts, the resistance goes to nill due to the contained plasma. A lot of current will worry it's way around your improvised gap because the arc won't be stable. Airgapping simply isn't a good idea here.
     
  13. rangebowdrie
    Joined: Nov 2009
    Posts: 102
    Likes: 38, Points: 28, Legacy Rep: 10
    Location: Oregon

    rangebowdrie Senior Member

    Yeah, you're probably right.
    I seem to remember from my days of ham radio, when I was interested in early Marconi wireless, (Spark Gap transmitters,) that the frequency was controlled by a combination of an inductor coil, and the distance of the gap.
    Huge amounts of spurious radiation, (electrical noise across a wide band).
    It's quick and easy for me to simply lift a floorboard and screw the bolt in to close the contact, (so no gap,) if the weather looks like strikes may occur.
    I've never heard of any strikes in my area that hit boats, but I'll look into an ESA,, thanks for the heads-up.
     
  14. wesley Sherman
    Joined: Jan 2020
    Posts: 77
    Likes: 10, Points: 8
    Location: New York

    wesley Sherman Junior Member

    No, it's no longer there, I removed it due to damage I suppose from impacts over the years and a bit of corrosion. I will be installing another new plate directly below the mast. My current knowledge or plan is to install just the mast to this plate and bond the rest of the boat and engine to a separate plate below where all my electronics will be.

    I am wondering is there a way to isolate all electronics when a storm comes. As in a way to discharge all electrical current from the electrical components and remove all connections to any power? Would having all components offline and disconnected from power source and ground prevent damage?
     
    Last edited: Dec 16, 2020

  15. missinginaction
    Joined: Aug 2007
    Posts: 1,054
    Likes: 225, Points: 63, Legacy Rep: 512
    Location: New York

    missinginaction Senior Member

    I've never been hit but my understanding is that you're pretty much at the mercy of the strike if it ever happens to you. I suppose that you could unplug all your antennas and turn off your main breaker but even then I've read about extensive damage being done to electronics during strikes. Then again you'll hear of boats being hit with minimal to no damage being done to the electronics and control systems. Read Calders book and you'll get a good understanding of this. For me the name of the game is staying alive, everything else is secondary.
     
Forum posts represent the experience, opinion, and view of individual users. Boat Design Net does not necessarily endorse nor share the view of each individual post.
When making potentially dangerous or financial decisions, always employ and consult appropriate professionals. Your circumstances or experience may be different.