That's what i have heard over the years. I doubt there is ANYTHING that can prevent lightening hits.
Lightning protection?
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We bought a 1990 Island Packet 38 that had been set up for lightning protection. The idea is not to offer a path for the strike to pass down the mast to the water. The method is to make all the metal and the boat have the same electrical potential as the water it is floating in. In other words: to make the boat invisable. All the metal items were bonded commonly to a large metal plate deep down on the outside of the keel.
Someone spent alot of time installing this system and the boat has been safe for 22 years. The boat that the previous owners bought after ours was hit before they installed this system on it.
Ray
Someone spent alot of time installing this system and the boat has been safe for 22 years. The boat that the previous owners bought after ours was hit before they installed this system on it.
Ray
My boat was built in 1968 has no system of lightning protection and has not been hit . My house is one of about four hundred in this subdivision and is from 1967 and has not been hit but one house ten feet lower in elevation and 450 feet to our north and twenty years newer has been struck twice. When you can explain that then you can have credability.
Ours has the same system. That is pretty much what ABYC suggests.. We were hit. There is NO system of "lightning protection" that has not been hit... After we were hit I did a ton of research which included recruiting a friend who works for a large marine underwriter. It took a while but he got to his actuarials who compre claims data. Bottom line was EVERY hocus pocus "system" of "protection" has been hit. Properly sized and installed down down conductors can help minimize side flashes and help to save lives but NO system on the planet will protect your electronics. Hell we lost multiple devices that were not even plugged in, including our EPIRB and all back up hand held GPS devices..
If there was ANY system that even began to edge out another in safety or claims reduction the insurance companies would be offering a discount if you had one and the ABYC would make it a mandatory part of the standards rather than a "suggestion".
If lightning wants your boat it will get it.....
There was some study recently that indicated that most lightning strikes exit the boat at the water line. The theory being that the cloud has one charge and induces an opposite charge beneath it on the SURFACE of the water. The depth of this charged up water layer is on the order of fractions of an inch.
SOOOOO if you try to get the lightning to go down the mast and exit through the keel you are actually trying to drive the electrical current past the charged up layer. Lightning apparently does not like to do that much and turns a corner to get to the water SURFACE. Land based lightning protection ALWAYS routs the current OUTSIDE the living spaces. Current thinking is that boats should adopt this concept too.
Attaching a wire to the shrouds/stays and having some sort of "terminal" at the water line would satisfy this. I personally just have a wire over the toe rail from each shroud leading down to the water.
FWIW
SOOOOO if you try to get the lightning to go down the mast and exit through the keel you are actually trying to drive the electrical current past the charged up layer. Lightning apparently does not like to do that much and turns a corner to get to the water SURFACE. Land based lightning protection ALWAYS routs the current OUTSIDE the living spaces. Current thinking is that boats should adopt this concept too.
Attaching a wire to the shrouds/stays and having some sort of "terminal" at the water line would satisfy this. I personally just have a wire over the toe rail from each shroud leading down to the water.
FWIW
Our Sabre is set up with 8 AWG. The mast, chainplates & thru hulls are all bonded to the keel.
On the same night our boat was hit a little Call 22 was also hit. According to the yard and surveyor the boat had no down conductor between the mast and the keel and no lightning system to speak of. It blew holes in the hull where the VHF cable had been run back to the radio where it was resting / laying on the hull behind the settee. It had no other "exit" point and the combination of a damp bilge and VHF wire resting on it likely gave it the path of least resistance.
Our boat, struck during the same storm, had zero hull damage and uses the keel as the main down conductor lightning ground along with secondary conductors. Everything on-board was fried but she did not sink like the little Cal.. The lightning grounds also pick up chain plates, engine and other metal fittings as secondary conductors. We have plenty of wires in the boat near the waterline that the strike could have used to blow holes in the hull but I surmise the more direct path to the keel, with less resistance, took the brunt of it.
When this strike happened there were over 1100 sailboats moored in Falmouth Foreside.
(Image Courtesy SkyPic.com)
The two boats hit that night could not have been more different. The Cal had one of the shortest masts and according to the surveyor, no lightning system what so ever. It had holes blown in the hull from the VHF cable. So there goes the "taller masts will get hit first" urban myth. Perhaps 97% of the boats in Falmouth have a taller mast than a Cal 22.... It still got blasted... It also blew the myth of "don't provide a path to ground and you won't get hit".. This boat had no low resistance path to ground from the mast to the keel or a lightning plate. It still got blasted....
Our boat has a medium sized mast for the anchorage and is wired to ABYC standards with regards to lightning. She had ZERO hull damage, but still got hit. A few years ago I was feeling pretty smug when the boat directly behind us, about 20 yards away, got hit. He had just spent nearly 4k on the "latest and greatest" lightning system including a brand new fuzzy dissipator/lightning attractor.... His boat was hit no less than 3 weeks after spending 4k on this "latest & greatest" lightning system. His boat also did not sink or have holes blown in it, so maybe it worked, but his entire boats electronic systems were toast.
The Cal:
I've come to realize that if lightning wants your boat, it will get it, and there's not a darn thing you can do. Other than to try and minimize hull damage and minimize the potential for side flashes if you get hit your gear is likely toast or will be shortly there after..
If you do get hit get your OWN surveyor and be sure to write up EVERYTHING electronic on-board. We had a couple of items still "operable" after the strike and they died within a month or two. Lucky we had a good surveyor who wrote it up for 100% replacement of all electronic devices.
Just be glad your boat does not have a carbon fiber spar. My friend Kim & her husband were hit to the tune of nearly 6 figures because a carbon spar hit by lightning is quite often a total loss..... Their boat had $65,000 carbon rig as well as sails that had holes burned in them.......
AND not all lightning strikes are created equal. I have seen strikes that have torn bark and wood in a four inch wide path down a hundred foot tall white oak and thrown the pieces fifty yards. Sometimes when lightning strikes the beach it fuses the sand into glass. Sometimes people get struck by lightning and live to tell it.
Nope. Like I said, it's just my opinion based on lots of little things I've read or have heard over the last ten years. Take it for what it's worth, remembering that "nobody knows anything" when it comes to lightning.
Speaking of Faraday cages, I have heard that it can be a pretty good idea if you're going offshore to take a cheap handheld GPS, wrap it in aluminum foil, and put it in your oven. Just in case.
Guys I'd suggest taking 5 minutes and reading this NOAA paper on lightning basics....
http://www.nssl.noaa.gov/primer/lightning/ltg_basics.html
From it you can see that there are two basic types of lightning that involve the ground vs. cloud to cloud. Triggered, ground to cloud, that involve towers on mountains, tall buildings and such. Our masts are tall to us, but not tall enough to cause 'triggered' strikes.
The other is natural, cloud to ground, and it is these that can hit our boat. They step from the cloud to the ground in 50 yard segments...
... and it is not until they get down near the ground that they are ....
Here Bill made a good point...
http://purplesagetradingpost.com/sumner/macgregor2/outside-43.html
...to see how it held up to salt water over time. We are not interested in trying to protect all of our electrical equipment and such on our smaller water ballast boat, but trying to divert the lightning away from the bottom of the deck stepped mast to the water hopefully so that it doesn't jump through the bottom of the boat and blow a hole through it plus we are also in the cabin.
Do I believe that this will keep lightning away from the boat? No. Do I believe that it will attract it? No and studies back that up.
Do I believe that it would divert any and all strikes to the water with no boat damage? No.
What I do believe is that it might give us a better chance of escaping a lightning strike. Kind of like you buying a car with an air bag and seat belts and using them. Do you think they would save you from every possible accident? Probably not, but you still use them.
They might not know everything about lightning, but there is enough know about it that systems are in place on towers, buildings, rockets, planes and such that do offer some degree of protection,
Sum
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http://www.nssl.noaa.gov/primer/lightning/ltg_basics.html
From it you can see that there are two basic types of lightning that involve the ground vs. cloud to cloud. Triggered, ground to cloud, that involve towers on mountains, tall buildings and such. Our masts are tall to us, but not tall enough to cause 'triggered' strikes.
The other is natural, cloud to ground, and it is these that can hit our boat. They step from the cloud to the ground in 50 yard segments...
... and it is not until they get down near the ground that they are ....
... or our mast. At that point the boat that is closer with the 30 foot mast might still be a shorter distance to ground than the boat 100 feet away with the 50 foot mast. So it is all basically luck. The strike that starts up at maybe 5 miles does not at that point see one boat or the other. It is just when it is down at its last 50 yard segment that it looks for the best target and shortest way to ground.
Here Bill made a good point...
If you have looked at photos of lightning hitting the water you can see that it isn't trying to go into the water, but spreads out in multiple streamers at the waters surface. Some effort has gone into lightning protection systems that try and route the lightning to the water's surface. We field tested such a system...
http://purplesagetradingpost.com/sumner/macgregor2/outside-43.html
...to see how it held up to salt water over time. We are not interested in trying to protect all of our electrical equipment and such on our smaller water ballast boat, but trying to divert the lightning away from the bottom of the deck stepped mast to the water hopefully so that it doesn't jump through the bottom of the boat and blow a hole through it plus we are also in the cabin.
Do I believe that this will keep lightning away from the boat? No. Do I believe that it will attract it? No and studies back that up.
Do I believe that it would divert any and all strikes to the water with no boat damage? No.
What I do believe is that it might give us a better chance of escaping a lightning strike. Kind of like you buying a car with an air bag and seat belts and using them. Do you think they would save you from every possible accident? Probably not, but you still use them.
They might not know everything about lightning, but there is enough know about it that systems are in place on towers, buildings, rockets, planes and such that do offer some degree of protection,
Sum
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Our Endeavour 37
Our MacGregor 26-S Pages
Our Trips to Utah, Idaho, Canada, Florida
Mac-Venture Links
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Me. An electrical storm was approaching, but the sun was shining. The following narrative happened in less than 1 second: The strike came from the leading edge of the cell and hit a tall locust in the field above the house. We were gathering aluminum lawn furniture and beating a retreat. The tree exploded and a grid of blue arcing lightning swept down the hill maybe 12" off the ground traveling 300 yards in a flash. Looked like electric varicose veins. As the electricity surrounded us, my guest was knocked to the ground in spasms. My arm that was resting on a metal chair instantly went uncontrollably straight up, metal chair in hand. My legs spasmed and I found myself flying backward at least two feet off the ground, landing 10 feet away, with chair in hand. It was over in 1 second.
Rolled onto my belly, gathered up my panicked guest, and we did the combat crawl to the back door of the house, slithered into the mudroom and stayed down waiting on the next hit. It never came. Amazing thing - another guest was in the upstairs shower. She never even knew there had been a storm, and no one was injured (other than a new anxiety around lightning).
The strange thing was that this old farmhouse was repeatedly hit by lighting while I lived there. Phones blown up, well pumps blown up, even an arc between two woodstove pipes while I stood in the room. The electrician who diagnosed the problem determined that the remote location on a knob, at the end of a long powerline run was susceptible and that the house electric service had a poor ground. The strike would run through the house until it found the telecom ground, whereupon it would blow the service box off the house like it had been hit by OO 10 ga. buckshot. He installed an array of 4 ground rods driven 8 ft into the ground, wired together and connected to the service ground with a wire as big as a pencil. He theorized that the house was charging up from the lightning surges like a big capacitor or something. He wrote it up in Fine Homebuilding a few years later with a few flourishes.
Not arguing, just discussing, so please take it in the spirit in which it is intended.
There is irrefutable, overwhelming statistical evidence that air bags and seat belts work. There is no such evidence that any marine lighting protection system provides the slightest benefit whatsoever. If there were, we wouldn't be having this discussion, because we'd all own it already. I imagine the Coast Guard and insurance companies would require it!
If towers, buildings, rockets, and planes floated, I suspect they'd get as hosed up by lighting strikes as boats do. The systems on buildings just provide a path to ground to reduce fires, but a building that's hit still usually suffers a lot of electrical damage. Rockets and planes don't have a path to ground when they're in flight, so their systems are really for hardening the onboard electronics to withstand the high surge voltages that come with a strike. Let lightning hit them while they're floating in a big puddle of salt water, and I'll bet they'd be in a pretty bad way.
Actually, we do know a lot about lightning. It isn't 100% predictable, but we do understand the physics and characteristics of what it is. There are proven methods to protect you and your equipment in the event of a strike. An analogy could be hurricanes. We know a lot about them, and know many things we can do to protect ourselves from them, but we can't prevent them or steer them away.robertsapp said:
Faraday cage works on the principal that a magnetic field will generate a voltage on a ferrous conductor as the magnetic field rises and falls as the surge or strike happens. The cage would redirect the magnetic flux to the cage structure and reduce the magnetic field inside which reduces the amount of induced voltage on the device inside. Aluminum foil is not ferrous and serves no purpose. The oven however is likely a good example, especially if grounded.
Lightning isn't a wild and unpredictable mystery. I work on systems daily that are protected from lightning strikes. We do nothing to attempt to prevent strikes, we do, prevent damage from strikes though.
Me to
Not in all cases but enough to hopefully get people to use them.robertsapp;923760[COLOR=#1c1d21 said:
There is evidence. Here is one source..
http://edis.ifas.ufl.edu/sg071
The ABYC has recommendations for lightning protection...
http://www.kp44.org/LightningProtectionABYC_Standards.php
This would be a very hard thing for insurance companies to implement.
Just so it is clear I'm just stating information that I've read and I have no financial interest or any other interest in what Ruth and I had on our boat in Florida that I mentioned in the other post. We choose to do something and that is the something that we will use on the water balest boat. Not sure yet on what we will use on the Endeavour, but might use a form of it on that boat also.
I can see that you have no faith that any form of protection is worth investing in. That is fine also with me,
Sum
Forrest15112, You almost have it right. A moving magnetic field induces a current in any conductor. A current flowing in any conductor induces a magnetic field around the conductor. The Farraday cage was invented by Mr. Farraday. A lightning discharge ionizes the air thus making the air a conductor and thus inducing a magnetic field. The magnetic field is a broad spectrum of radio frequency emmissions. That is the cause of the static that you hear on an AM radio receiver. We all live in a constant magnetic field and it does us no harm but it does make our compass work. We use noise suppressor spark plugs on our cars to quiet the noise from the ignition system . Inside a farraday cage you would measure no spark noise generated on the outside.
I really thought this was going to end with that bolt of lightning leaving the gallon can and hitting the nasa engineer's car across from Nice N Easy.
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