Does anybody have any experience or opinions about the Strikeshield system for grounding a mast? Thanks.
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Lightning protection is like
the man who was shredding cigarettes and sprinkling the tobacco around himself. Someone ask why and he replied that it keeps the tigers away. But there are no tigers within 100 miles of here. It works pretty good ,doesn't it.
the man who was shredding cigarettes and sprinkling the tobacco around himself. Someone ask why and he replied that it keeps the tigers away. But there are no tigers within 100 miles of here. It works pretty good ,doesn't it.
2 schools of thought
One school of thought is that you connect everything together, throw some zincs on it and then the lightning will go down the mast and exit the boat harmelessly (mostly not blowing a hole in the boat harmless). The other school of thought is that you don't connect anything together and so the mast does not "see/feel" a ground and is not able to participate in a lightning strike. The truth is neather system works 100%. When dealing with billions of volts and amps in microseconds you are not going to get a system as small as a boat to have a chance in heck of getting away totally unschathed. Protect your people and try to not get the hull blown up. I personaly think that an 00 cable with a battery clamp on one end and a metal plate on the other give me the best options. I do not ground the mast to the keel but do attach the battery clamps to the shrouds and throw the other end in the water. Should a strike happen the easiest path to ground is the masthead- shroud-cable-metal plate-water. This keeps the strike out of the boat at least. Of course we are using hope as a method here and nothing is assured. Google "sailboat lightning" for some interesting reading. It is astounding what can occure with a lightning strike.
One school of thought is that you connect everything together, throw some zincs on it and then the lightning will go down the mast and exit the boat harmelessly (mostly not blowing a hole in the boat harmless). The other school of thought is that you don't connect anything together and so the mast does not "see/feel" a ground and is not able to participate in a lightning strike. The truth is neather system works 100%. When dealing with billions of volts and amps in microseconds you are not going to get a system as small as a boat to have a chance in heck of getting away totally unschathed. Protect your people and try to not get the hull blown up. I personaly think that an 00 cable with a battery clamp on one end and a metal plate on the other give me the best options. I do not ground the mast to the keel but do attach the battery clamps to the shrouds and throw the other end in the water. Should a strike happen the easiest path to ground is the masthead- shroud-cable-metal plate-water. This keeps the strike out of the boat at least. Of course we are using hope as a method here and nothing is assured. Google "sailboat lightning" for some interesting reading. It is astounding what can occure with a lightning strike.
Carry a rabbit's foot it will be just as effective
I like the tiger story and that is what people that sell these systems rely on. A strike and the damage it may cause is a matter of random luck as we are unable to harness the forces involved. The only sure thing you can do is insure the boat properly and keep the premiums up. To protect yourself keep away from metals and pray.
I like the tiger story and that is what people that sell these systems rely on. A strike and the damage it may cause is a matter of random luck as we are unable to harness the forces involved. The only sure thing you can do is insure the boat properly and keep the premiums up. To protect yourself keep away from metals and pray.
You guys left out one more line of thought.
Grounding the mast PREVENTS a strike. With the mast grounded, the return wave is grounded and no strike path is available. That's why all those aluminum masts aren't hit ALL the time. Happened to me. No ground=strike. With a ground, nothing.
Grounding the mast PREVENTS a strike. With the mast grounded, the return wave is grounded and no strike path is available. That's why all those aluminum masts aren't hit ALL the time. Happened to me. No ground=strike. With a ground, nothing.
I don't know, but I can guess.
Ross, I don't think anyone claims to have all the answers with lightening. But, here's a guess; Have you ever driven across the plane states during a lightening storm? You know, miles of visible sky and scattered trees? Lightning bolts can be seen shooting across the sky for a hundred miles or more. Where they hit is anybodies guess. But certain types of lightening must strike or they wouldn't exist. Sooner or later they'll find something to their liking. Think about people on a golf course that has trees. The people get hit because they don't ground themselves as well or better than the trees. In the northwest, we have nothing but trees. It's gotta go somewhere. Often it's to an old dried up snag (low moisture content=poor ground=fire too). Don't get me wrong. I'm no expert. I've just read up a lot on the subject and keep an eye on the world. It's a cool subject even if it's scary.
Ross, I don't think anyone claims to have all the answers with lightening. But, here's a guess; Have you ever driven across the plane states during a lightening storm? You know, miles of visible sky and scattered trees? Lightning bolts can be seen shooting across the sky for a hundred miles or more. Where they hit is anybodies guess. But certain types of lightening must strike or they wouldn't exist. Sooner or later they'll find something to their liking. Think about people on a golf course that has trees. The people get hit because they don't ground themselves as well or better than the trees. In the northwest, we have nothing but trees. It's gotta go somewhere. Often it's to an old dried up snag (low moisture content=poor ground=fire too). Don't get me wrong. I'm no expert. I've just read up a lot on the subject and keep an eye on the world. It's a cool subject even if it's scary.
Lightning Ground
Grounding an air terminal attachment point, such as a mast, does NOT prevent (nor reduce the likelihood of) a lightning strike. The only purpose of a Lightning Grounding System is to provide a preferred electrical path to ground. Neither does it relieve the static charge build-up(ionic discharge), enough to reduce the chance of a strike.
Grounding an air terminal attachment point, such as a mast, does NOT prevent (nor reduce the likelihood of) a lightning strike. The only purpose of a Lightning Grounding System is to provide a preferred electrical path to ground. Neither does it relieve the static charge build-up(ionic discharge), enough to reduce the chance of a strike.
Gord
Why? Who made that statement? How do they know? If a mast is grounded how would THEY know what the purpose of said grounding was for, or why it worked? And what research has been done to insure that the grounding is working one way and not the other? I haven't seen it. Just assumptions by the experts that the system works the way they think.
Why? Who made that statement? How do they know? If a mast is grounded how would THEY know what the purpose of said grounding was for, or why it worked? And what research has been done to insure that the grounding is working one way and not the other? I haven't seen it. Just assumptions by the experts that the system works the way they think.
A very worthwhile effort can
be made reading the last twenty years of research published in Scientific American and in Nature magazine on the studies that have been done on lightning. Everything that we know and think we know about the behavior of lightning is not adequate to explain all of the different circumstances and effects of a lightning strike. The insurance companies will NOT reduce your homeown insurance premiums because you have installed a "Lightning Protection System".
be made reading the last twenty years of research published in Scientific American and in Nature magazine on the studies that have been done on lightning. Everything that we know and think we know about the behavior of lightning is not adequate to explain all of the different circumstances and effects of a lightning strike. The insurance companies will NOT reduce your homeown insurance premiums because you have installed a "Lightning Protection System".
There is research
I'm traveling, so I don't have any of the links, but there are great, technically competent articles on the web, backed up by excellent research. Key conclusions discused and backed up on this site (check the archives) include: Grounding the mast to the keel, or to at least one square foot of copper in contact with the water, does protect the boat from some of the effects of being hit. It significantly reduces the probability of side forks that can take the strike through the hull below the water line, and sink the boat fast. The research does indicate that the chances of a grounded mast being struck are slightly higher. Bonding metal through-hulls to a ground can prevent them from being blown out of the boat by a strike - again, causing serious danger of sinking. Paint on a lead or steel keel does not seriously reduce its grounding capacity. A fiberglass layer will. All of this works better in salt water than in fresh, presumably because the below water electrode connects more effectively with water with a high ion (salt) content. You are likely to lose your electronics to any strike, although there are protective elements you can put in your antenna line. The mast, shrouds, aluminum toerails, grounding wire and keel do offer a substantial cone of safety to crew in the cockpit or cabin, away from the mast or other conducting elements (for instance wheel steering.) David LAdy Lillie
I'm traveling, so I don't have any of the links, but there are great, technically competent articles on the web, backed up by excellent research. Key conclusions discused and backed up on this site (check the archives) include: Grounding the mast to the keel, or to at least one square foot of copper in contact with the water, does protect the boat from some of the effects of being hit. It significantly reduces the probability of side forks that can take the strike through the hull below the water line, and sink the boat fast. The research does indicate that the chances of a grounded mast being struck are slightly higher. Bonding metal through-hulls to a ground can prevent them from being blown out of the boat by a strike - again, causing serious danger of sinking. Paint on a lead or steel keel does not seriously reduce its grounding capacity. A fiberglass layer will. All of this works better in salt water than in fresh, presumably because the below water electrode connects more effectively with water with a high ion (salt) content. You are likely to lose your electronics to any strike, although there are protective elements you can put in your antenna line. The mast, shrouds, aluminum toerails, grounding wire and keel do offer a substantial cone of safety to crew in the cockpit or cabin, away from the mast or other conducting elements (for instance wheel steering.) David LAdy Lillie
Every researcher
Fred: You’re free to ignore the experts' opinions - but I wish you wouldn’t share that ignorance (of virtually all the research) with others who (rightfully) respect your opinion. CODES & STANDARDS: LPI-175: The lightning protection code, published by the Lightning Protection Institute. NFPA 78: National Fire Protection Association Lightning Protection Code. ASAE EP381: American Society of Agricultural Engineers, Engineering Practice. 96AUL: Requirements for Master Label for Lightning Protection, developed by Underwriters' Laboratories. REFERENCES National Severe Storms Laboratory www.nssl.noaa.gov/researchitems/lightning.html National Lightning Safety Institute www.LightningSafety.com/index.html University Of Florida (Boating-Lightning Safety) http://www.thomson.ece.ufl.edu/lightning/SGEB17.html http://www.cdc.gov/nasd/docs/d000001-d000100/d000007/d000007.html “A Critical Assessrnent of the U.S. Code for Lightning Protection of Boats” E.M.Thomson,, Institute of Electrical and Electronic Engineers Transactions on Electromagnetic Compatibility, Volume 33, Number 2, pp. 132-138,1991 http://www.thomson.ece.ufl.edu/lightning/IEEE.pdf National Weather Service www.LightningSafety.noaa.gov National Agricultural Safety Database (Boating-Lightning Protection) www.cdc.gov/niosh/nasd/docs/as04800.html Including: http://www.cdc.gov/nasd/docs/d001801-d001900/d001825/d001825.html http
Fred: You’re free to ignore the experts' opinions - but I wish you wouldn’t share that ignorance (of virtually all the research) with others who (rightfully) respect your opinion. CODES & STANDARDS: LPI-175: The lightning protection code, published by the Lightning Protection Institute. NFPA 78: National Fire Protection Association Lightning Protection Code. ASAE EP381: American Society of Agricultural Engineers, Engineering Practice. 96AUL: Requirements for Master Label for Lightning Protection, developed by Underwriters' Laboratories. REFERENCES National Severe Storms Laboratory www.nssl.noaa.gov/researchitems/lightning.html National Lightning Safety Institute www.LightningSafety.com/index.html University Of Florida (Boating-Lightning Safety) http://www.thomson.ece.ufl.edu/lightning/SGEB17.html http://www.cdc.gov/nasd/docs/d000001-d000100/d000007/d000007.html “A Critical Assessrnent of the U.S. Code for Lightning Protection of Boats” E.M.Thomson,, Institute of Electrical and Electronic Engineers Transactions on Electromagnetic Compatibility, Volume 33, Number 2, pp. 132-138,1991 http://www.thomson.ece.ufl.edu/lightning/IEEE.pdf National Weather Service www.LightningSafety.noaa.gov National Agricultural Safety Database (Boating-Lightning Protection) www.cdc.gov/niosh/nasd/docs/as04800.html Including: http://www.cdc.gov/nasd/docs/d001801-d001900/d001825/d001825.html http
Yep, Thanks Gord. Now this from your last link;
"Lightning occurs when the imbalance between charges becomes too great. Certain weather conditions can cause an abundance of negative charges to gather on the bottom of clouds, while positive charges accumulate on buildings, trees, or any objects that project above the ground. When the negative and positive charges build to high enough levels, a streamer of negative charges moves erratically toward the earth. At the same time, a short leader of positive charges may move a short distance up into the air. When the two charges meet, the downward moving streamer completes the grounding path as the positive charges instantaneously move back up the path to the clouds (see fig. 1). The resulting flash is lightning. A lightning "stroke" happens very quickly and contains a great deal of electrical energy." That's my point. My boat was hit because I sealed up the keel too well. We survived incredible strikes within 50' of the boat, all rainy season in Costa Rica. Nothing. No damage. Not one hit to our friends either. Then we split up. I hauled the boat and sealed up the keel. Bad. That was my lightening protection. I was no longer grounded. I pulled out of Costa Rica and was hit by lightening. NO OTHER STRIKES OCCURRED! Just the one that hit my boat. WHAT'S THAT TELL YOU? Overcharged and nothing to ground the risers. It blew hundreds of holes from the keel coating. Not to mention $15,000.00 worth of electronics. Practical Sailor ran a story about 15 years ago about mast grounding and why it's done. Their point was mine. Most everybody is thinking that we have to ground strikes to minimize damage. Their point was that we ground to PREVENT strikes. It happened to me. Oh, I installed a ground plate right after the strike and the lightening hits elsewhere. Gord, this is not just my opinion. And I am not doing a dis-service to my fellow sailors. And Gord, No where did I say anything that was irresponsible. Grounding is still needed. Claiming otherwise is irresponsible. IMHO
"Lightning occurs when the imbalance between charges becomes too great. Certain weather conditions can cause an abundance of negative charges to gather on the bottom of clouds, while positive charges accumulate on buildings, trees, or any objects that project above the ground. When the negative and positive charges build to high enough levels, a streamer of negative charges moves erratically toward the earth. At the same time, a short leader of positive charges may move a short distance up into the air. When the two charges meet, the downward moving streamer completes the grounding path as the positive charges instantaneously move back up the path to the clouds (see fig. 1). The resulting flash is lightning. A lightning "stroke" happens very quickly and contains a great deal of electrical energy." That's my point. My boat was hit because I sealed up the keel too well. We survived incredible strikes within 50' of the boat, all rainy season in Costa Rica. Nothing. No damage. Not one hit to our friends either. Then we split up. I hauled the boat and sealed up the keel. Bad. That was my lightening protection. I was no longer grounded. I pulled out of Costa Rica and was hit by lightening. NO OTHER STRIKES OCCURRED! Just the one that hit my boat. WHAT'S THAT TELL YOU? Overcharged and nothing to ground the risers. It blew hundreds of holes from the keel coating. Not to mention $15,000.00 worth of electronics. Practical Sailor ran a story about 15 years ago about mast grounding and why it's done. Their point was mine. Most everybody is thinking that we have to ground strikes to minimize damage. Their point was that we ground to PREVENT strikes. It happened to me. Oh, I installed a ground plate right after the strike and the lightening hits elsewhere. Gord, this is not just my opinion. And I am not doing a dis-service to my fellow sailors. And Gord, No where did I say anything that was irresponsible. Grounding is still needed. Claiming otherwise is irresponsible. IMHO
Don't stop shredding ...
I doubt that your “... boat was hit because I (you) sealed up the keel too well ...” so much as because you stopped “... shredding cigarettes and sprinkling the tobacco around ...”.
Sorry for my earlier outburst. I get so frustrated by pseudo-science, that I didn’t truly comprehend your post.
I doubt that your “... boat was hit because I (you) sealed up the keel too well ...” so much as because you stopped “... shredding cigarettes and sprinkling the tobacco around ...”.
Sorry for my earlier outburst. I get so frustrated by pseudo-science, that I didn’t truly comprehend your post.Fred, I doubt that the mast was not grounded
when the keel was sealed up. Most sailboats with inboards, have the mast grounded. Grounding does not require a heavy ground strap or attachment to a keel or plate, those are adequate grounding. Grounding occurs when even a small wire such as the shield wire for the vhf finds a path to ground such as through the engine ground strap and transmission and prop shaft. Fred, your mast wasn't ungrounded, it just wasn't adequately grounded. It was grounded adequately to particpate in the streamer-leader game that lightning plays. On the other hand, a trailer sailor with an outboard likely has an ungrounded mast unless he is in a marina and hooked up to shore power.
when the keel was sealed up. Most sailboats with inboards, have the mast grounded. Grounding does not require a heavy ground strap or attachment to a keel or plate, those are adequate grounding. Grounding occurs when even a small wire such as the shield wire for the vhf finds a path to ground such as through the engine ground strap and transmission and prop shaft. Fred, your mast wasn't ungrounded, it just wasn't adequately grounded. It was grounded adequately to particpate in the streamer-leader game that lightning plays. On the other hand, a trailer sailor with an outboard likely has an ungrounded mast unless he is in a marina and hooked up to shore power.
uninformed question
I feel like I'm diving into a tank with sharks but will qualify myself by adding that I have no heady knowledge on this subject but rather a basic question. Last year we were sitting in the marina during a pretty good lightning storm. I'm pretty sure the mast is grounded to the keel properly and I'm pretty sure we were hooked into the shore power. I stepped outside to watch some of the show and heard a distinct buzzing coming from our mast/rigging. There were several other boats around us and I walked around to see if anyone else was buzzing, they were not. I proceeded (perhaps pseudo-scientifically) to grab whatever chain I had laying around and hooked it around the shrouds and dropped it into the water. I had no idea if this would help or hurt but I think it made me, and more importantly my wife, feel better that I had actually spread that tobacco-chain around the boat. The buzzing did not stop, but we were not hit either, and in the eyes of my wife I was the hero. Now, since I'm offering my un-scientific theory here for a public de-bunking, I trust none of you will tell my wife.
I feel like I'm diving into a tank with sharks but will qualify myself by adding that I have no heady knowledge on this subject but rather a basic question. Last year we were sitting in the marina during a pretty good lightning storm. I'm pretty sure the mast is grounded to the keel properly and I'm pretty sure we were hooked into the shore power. I stepped outside to watch some of the show and heard a distinct buzzing coming from our mast/rigging. There were several other boats around us and I walked around to see if anyone else was buzzing, they were not. I proceeded (perhaps pseudo-scientifically) to grab whatever chain I had laying around and hooked it around the shrouds and dropped it into the water. I had no idea if this would help or hurt but I think it made me, and more importantly my wife, feel better that I had actually spread that tobacco-chain around the boat. The buzzing did not stop, but we were not hit either, and in the eyes of my wife I was the hero. Now, since I'm offering my un-scientific theory here for a public de-bunking, I trust none of you will tell my wife.
WhenI was stationed in the Philipine Islands
I was a radio repairman on duty alone with thunder storms moving into the area but it had not started raining. I kept hearing a snap of the sort you get with sparks. I found a coax connector that fed a long wire antenna was providing a discharge path for the static that built up on the longwire. The sparks came about every ten seconds and jumped a 3/8 gap. No. I didn't try to measure the voltage.
I was a radio repairman on duty alone with thunder storms moving into the area but it had not started raining. I kept hearing a snap of the sort you get with sparks. I found a coax connector that fed a long wire antenna was providing a discharge path for the static that built up on the longwire. The sparks came about every ten seconds and jumped a 3/8 gap. No. I didn't try to measure the voltage.
SGEB-17
I suggest you read Dr Thomson’s excellent tutorial, “Lightning & Sailboats” (SGEB-17) at: .thomson.ece.ufl.edu/lightning/SGEB17.html <quote> “... Others signs of imminent lightning are even more obvious. St. Elmo's fire and buzzing sounds off radio antennas arise when a boat is in the large electric field directly below an electrifled cloud. Although lightning may not yet have begun, its occurrence in the immediate vicinity is exceedingly probable when these electrical phenomena are observed ...” <end quote>
I suggest you read Dr Thomson’s excellent tutorial, “Lightning & Sailboats” (SGEB-17) at: .thomson.ece.ufl.edu/lightning/SGEB17.html <quote> “... Others signs of imminent lightning are even more obvious. St. Elmo's fire and buzzing sounds off radio antennas arise when a boat is in the large electric field directly below an electrifled cloud. Although lightning may not yet have begun, its occurrence in the immediate vicinity is exceedingly probable when these electrical phenomena are observed ...” <end quote>
Dr. Thomson in my opinion practices junk science
for personal gain. His quoted Sea Grant study was not science but rather bias. In that study, he assumed very unscientifically that boats without a lightning protection systems had ungrounded mast... and concluded very wrongly that ungrounded mast had either equal or higher rates of hits than grounded... he gets absolutely no respect from me. His false conclusions appear to me to bolster his private enterprizes.
for personal gain. His quoted Sea Grant study was not science but rather bias. In that study, he assumed very unscientifically that boats without a lightning protection systems had ungrounded mast... and concluded very wrongly that ungrounded mast had either equal or higher rates of hits than grounded... he gets absolutely no respect from me. His false conclusions appear to me to bolster his private enterprizes.
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