I am concerned about the lack of Lightning Protection on my O'Day 27. The mast is not grounded. There are no keel bolts to ground to. I have read that the sintered bronze is not good to use (www.thomson.ece.ufl.edu/lightning), (also West Marine Advisor on Lightning). Does anyone know a source or supplier for Ground plates? I sail in the fresh waters of Lake Michigan, so I need additional square footage of ground plate. I am not sure how many square feet are required. The literature says one square foot for salt water and lots more for fresh water. I am considering using copper buss bar material (used in electrical equipment), bolted onto the bottom, on both sides of the keel. All suggestions will be appreciated. Thanks, John
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Justin - O'day Owners' Web
Lightning Protection
John - Lightning is still very much voodoo to the sailing world, but you are wise to be thinking about it. Before you do anything, have you read Nigel Caulder's section on protecting your boat? I go back and forth on the issue of whether to ground my mast or not. At the moment, its not grounded. There is the theory that you want to give the strike a clean path to ground so that people aboard don't get shocked, but at the same time providing a good ground may increase your risk of being hit in the first place. Read everything you can find. That said, I think bus bars would make decent conductors. Justin - O'day Owners' Web
John - Lightning is still very much voodoo to the sailing world, but you are wise to be thinking about it. Before you do anything, have you read Nigel Caulder's section on protecting your boat? I go back and forth on the issue of whether to ground my mast or not. At the moment, its not grounded. There is the theory that you want to give the strike a clean path to ground so that people aboard don't get shocked, but at the same time providing a good ground may increase your risk of being hit in the first place. Read everything you can find. That said, I think bus bars would make decent conductors. Justin - O'day Owners' Web
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Ken Cobb
Grounded beats sunk
I would think that the failure to provide a grounded route for the lightning to the water would increase the chance that the lightning would go down your mast and blast its way through your hull to the water. I have read of several cases boats sunk by lightning, both on the water and at dock. I don't know if they were grounded or not, though.
I would think that the failure to provide a grounded route for the lightning to the water would increase the chance that the lightning would go down your mast and blast its way through your hull to the water. I have read of several cases boats sunk by lightning, both on the water and at dock. I don't know if they were grounded or not, though.
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scott
not if but when
Down here in SW fla. lightning is a daily event for six months a year. I think most of us try to protect our boats in some way or another but nearly all realize that it is probably a matter of WHEN the boat gets hit rather than IF it will get hit. Good insurance is probably the best starting point for lightning protection. Like you I'm still reading all I can before I invest in some "voo doo" system. Good luck to us all, cause to me it is just that, luck.
Down here in SW fla. lightning is a daily event for six months a year. I think most of us try to protect our boats in some way or another but nearly all realize that it is probably a matter of WHEN the boat gets hit rather than IF it will get hit. Good insurance is probably the best starting point for lightning protection. Like you I'm still reading all I can before I invest in some "voo doo" system. Good luck to us all, cause to me it is just that, luck.
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J R
Just Hit
The night of June 14 my wife and I were aboard and in our slip. We had a very violent electrical storm move through the area. We took a massive hit to he masthead. I have one of those bottle brush dissipaters on the mast, a lightning rod spike, the mast is keel stepped and is grounded to a large bronze plate outside the hull. I also had a set of heavy battery cables clipped from the shrouds to the metal of the dock. We survived but all of our electrical equipment on the 12 volt system did not. About $12,000 so far. Did I do too much or too little? I don't know the answer but I am still here to ponder the question.
The night of June 14 my wife and I were aboard and in our slip. We had a very violent electrical storm move through the area. We took a massive hit to he masthead. I have one of those bottle brush dissipaters on the mast, a lightning rod spike, the mast is keel stepped and is grounded to a large bronze plate outside the hull. I also had a set of heavy battery cables clipped from the shrouds to the metal of the dock. We survived but all of our electrical equipment on the 12 volt system did not. About $12,000 so far. Did I do too much or too little? I don't know the answer but I am still here to ponder the question.
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Frank Walker
Asking For It
John, 1. All boats should have a properly installed grounding system period. The concept of an ungrounded mast is less lightly to be hit is BS. 2. There are no absolutes in the lightning protection business. Lightning protection systems reduce the probability of a strike but they do not reduce it to zero. However, when hit they safely control the path of current flow. 3. There is no practical way to protect boat electronic/electrical equipment from a direct hit. A proper lightning protection system should protect the occupants and the craft from a direct hit. On my boat I used a section of copper bus bar stock about 6"x24"x3/8". The electrical connections are via 3ea 1/2" silicon bronze bolts and they were soldered to the bar before installation. From the mast I have one ground wire connected to the plate and one ground wire connected to the keel bolts. Also have all shrouds, stays, pushpits, rub rail, and bimini top frame connected to keel bolts. The mast step is also connected to the ground plate which is located directly below the mast step. Your problem is getting enough perimeter to dissipate a strike in fresh water. Note the literature indicates that edge length or perimeter is more important than area. Heavy copper strapping might be easier to install rather than bus bar. There are a lot of horror stories about Dynaplates in lightning strikes. I am not sure I buy into the effective area theory, but I sure do not think a single 1/4 bolt is nearly large enough. Under ideal conditions maybe, but not typical bilge conditions. I could quote you some lab experiments that indicate that sharp points do reduce the probability of a direct hit. In my mind the brushes are in the same category as the Dynaplate, however because of some mechanical reasons I replaced my sharp point (they are called air terminals in the lightning protection business)with the Forespar brush. It has the most reasonable priced of the bunch. Install a proper system and sail in the knowledge that you have done your best to protect your family, your friends, and the craft. PS I am a practicing electrical engineer with 35 years experience and a good portion of that designing lightning protection systems. Frank Walker
John, 1. All boats should have a properly installed grounding system period. The concept of an ungrounded mast is less lightly to be hit is BS. 2. There are no absolutes in the lightning protection business. Lightning protection systems reduce the probability of a strike but they do not reduce it to zero. However, when hit they safely control the path of current flow. 3. There is no practical way to protect boat electronic/electrical equipment from a direct hit. A proper lightning protection system should protect the occupants and the craft from a direct hit. On my boat I used a section of copper bus bar stock about 6"x24"x3/8". The electrical connections are via 3ea 1/2" silicon bronze bolts and they were soldered to the bar before installation. From the mast I have one ground wire connected to the plate and one ground wire connected to the keel bolts. Also have all shrouds, stays, pushpits, rub rail, and bimini top frame connected to keel bolts. The mast step is also connected to the ground plate which is located directly below the mast step. Your problem is getting enough perimeter to dissipate a strike in fresh water. Note the literature indicates that edge length or perimeter is more important than area. Heavy copper strapping might be easier to install rather than bus bar. There are a lot of horror stories about Dynaplates in lightning strikes. I am not sure I buy into the effective area theory, but I sure do not think a single 1/4 bolt is nearly large enough. Under ideal conditions maybe, but not typical bilge conditions. I could quote you some lab experiments that indicate that sharp points do reduce the probability of a direct hit. In my mind the brushes are in the same category as the Dynaplate, however because of some mechanical reasons I replaced my sharp point (they are called air terminals in the lightning protection business)with the Forespar brush. It has the most reasonable priced of the bunch. Install a proper system and sail in the knowledge that you have done your best to protect your family, your friends, and the craft. PS I am a practicing electrical engineer with 35 years experience and a good portion of that designing lightning protection systems. Frank Walker
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