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Go Back   SailNet Community > Out There > Cruising & Liveaboard Forum > Living Aboard
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  #11  
Old 03-21-2003
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Lightning Anyone?

Ahoy, Me Mateys in all my years I never got struck on a boat or on the water. Then I moved to SW Florida. within thirty days I personally shook hands wit God almighty in a glorious flash of pure white light so beautiful and peacefull I thought at the beginning that, gee thats a strange kind of light? DUH ... The Two wenches sharing me bed at the time came running and although I could see thier mouths moving I couldn''t hear a thing. In fact for those wonderfull moments when I was talking to God.. ohh and by the way he looks more like Albert Einstien than George Burns , .. uhh oh yeah Time stood still . It''s a good thing cause he''s a little slow witted when it come to practical problem solving so it took me a while to answer all his questions,,.. uhh Anyway I wasn''t on the boat and though Me wenches thought me smoking hair and stunned look on me face meant I was dead I didn''t feel nothing. Felt fine in a couple of minutes when the hearing returned and all been well wit me since. De point I suppose youse slow witted mortals may need to hear is this . When God dials your number its best to answer and tell him I said Hello. Pirate of Pine Island. Deckstepped Mast grounded to water by large cables directly over the side to the water. Ugly but effective.
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  #12  
Old 03-22-2003
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Lightning Anyone?

Loved your most technical and informative response, I quote you as saying "A strike will be proportionate to the attraction of the mast and the negativity of the stormcloud. The strike needs a route from the masthead to saltwater in the shortest path with the least resistance."
SOUNDS GREAT IN THEORY... however the unexpected can also happen. We were struck by lightning on the stern of our boat while anchored out. We were sitting in the cockpit at the time (no, I wasn''t holding a mast in my hands)... when it struck I dove down the open companionway just as my husband grabbed me by the strap of my bra... to keep me from falling on my head! We laugh about it now... and I think he actually wasn''t trying to help ME as much as he was trying to get me out of HIS WAY to safety! BOTTOM LINE: Be prepared for anything, it can and will happen. Sometime, somewhere. We weren''t injured and the boat was fine... but I''ll never forget that sound and the light show on our stern, it was something like right out of the Twilight Zone!
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Old 03-22-2003
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Lightning Anyone?

Sorry, my response was directly to that of Date: Mar. 17 2003 2:56 PM
Author: maxcontax

Thanks!
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  #14  
Old 03-24-2003
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Lightning Anyone?

I spent the better part of a year studying static electricity and lightning strikes related to protecting metal buildings and steel towers, back in the mid-80''s, so the memory''s fading a bit--but there were a few things that stick in my mind. Firstly the the flukey and erratic, unpredictable nature of a strike: it does not always strike the highest point. It strikes the most charged point. It needs a "leader" from the object up into the charged atmosphere for the discharge to occur: sometimes in a video you see this, a faint leader reaching upwards before the strike downwards. the leader comes from an electrostatic charge or a source. Remove or reduce these and the strike chances are less. I remember at the time that I was doing all this industrial building protection there was a belief that if you ground out something too well, and put up too many lightning rods on a building, you may end up attracting lightning instead of reducing it. That went resolved. Glad no one got hurt. Wish there was a guaranteed recipe for protection. Does anyone try battery jumper cables overboard and clipped to the shrouds? If so, are they alive to tell the tale?
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  #15  
Old 03-24-2003
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Lightning Anyone?

maxcontax,

I have dropped a chain over the side that was attached to a side shroud while I was sailing on my old boat (deck stepped and encapsulated keel). I''m still here, even a few times when in the middle of a storm. I think its just luck....

But forget about attracting or not. I think the REAL good reason for grounding is not about attraction or less attraction, but rather, when it hits the odds are "MUCH" more in your favor of not getting a person on board bZAPPED if you boat/mast is grounded.....THAT is the reason for it IMHO.
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  #16  
Old 03-25-2003
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Lightning Anyone?

One thing not mentioned is the classical thunderstorm protection on a LAKE. Fresh water. not very conductive. Reducing static surfaces and getting a ground cable can''t hurt but getting off the lake is still the obvious best choice.
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  #17  
Old 04-23-2003
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Lightning Anyone?

I have been reading the thread on lightning protection with great interest and am amazed at the amount of misconceptions about the whole thing. Especially the information on lightning "prevention" systems or static dissipaters.
I think that it is safe to say that the information is wide ranging and confusing.
A few things are sure however, and need to be reiterated for the benefit of people wondering.
First of all there is no such thing as attracting a strike. Some individuals think that because they have the tallest mast in a marina that they are more susceptible to a strike or that installing a ground to the mast will increase the likelyhood of a strike. That is simply not true.
Secondly, there is no such thing as preventing a strike. Static dissipaters have been scientificially questioned by the IEEE and there are several papers written by scientific authorities documenting this. Two that are worth reading are:

http://www.strikeshield.com/Lightning%20info/mousaIEEEDissipators.pdf
This first paper was written as a result of a comprehensive study done for British Columbia Hydro on the effectiveness of static dissipaters. Dr. Moussa relied heavily on US data from NASA, the FAA and other scientific authorities.
and
http://www.thomson.ece.ufl.edu/lightning/IEEE.pdf
This paper written by the eminent Dr. Ewan Thomson of the university of Florida basically criticized the ABYC for recommending "seriously inadequate" measures for lightning protection.

All of the lightning authorities agree that there is only one solution to this problem and that is to properly ground ANY structure that is susceptible to a lightning strike and this includes boats. The problem for sailors is that most boat manufacturers DO NOT abide by the ABYC standards which recommend the installation of properly sized conductors to ground lightning energy from the mast to the water.
What are we left with ? Unprotected boats, improperly jury-rigged grounding devices such as chains and booster cables and complete confusion as to what to do.

A few important areas require attention of one is to create a lightning protection system;
Material selection and assembly procedures are quintessential to the success of such systems.
I shudder when I hear of people clamping booster cables to the stays of their sailboats. This is so dangerous !
The cable connectors are improperly sized and offer little contact surface. The result is an exploding vaporized copper clamp.
Using chains wrapped around masts is equally dangerous. The links are highly resistive and can overheat and melt the roof or set it on fire.
This has happened time and time again and yet people still believe that this is an acceptable solution. It is not.

Conductors must be properly sized. Nothing less than a 1/0 multi-stranded tinned copper marine shipboard cable should be used.
Wires must be connected using proper lugs that should be swaged onto the wire with an industrial hydraulic press. The connections should be tinned and then protected with a heat shrink. These methodologies and assembly techniques are used in the power industry. There are UL, ISO, ASTM and IEEE standards with respect to the use of cables for conducting power and they are the result of extensive testing and experience.These methods are the only acceptable methods of building such a system. Hardware store household No.4 wire saddle clamps are inadequate for marine applications.
Electrical connection to the mast must be made through a large contact area. Small clamps and screws or bolts are inadequate for sustaining multiple strikes. Copper parts and components should be tinned for corrosion resistance and to prevent galvanic reactions.
All parts used in the creation of such a system MUST be copper. Not Monel, Not Bronze, Not Stainless Steel or any other less conductive metal. Choosing materials other than copper only adds resistivity to the ground circuit which will cause this material to overheat. This principle is used in electric stoves. Steel wires with high current running through them turn red hot. Same thing will happen to these resistive metals if lightning energy comes through them.
Bonding Bronze Throughulls to the lightning ground is another good method of ensuring the boat sinks in the event of a strike. If the throughulls have lightning energy running through them, the current passing through will heat them up to the point where they may melt the surrounding fiberglass and pop out. Then you will have much more serious problems.
Finally the dissipation electrode in contact with water must be copper (tinned) and offer a large amount of edges as electrical energy will contact with water much more freely through edges than flat areas.

Chris L.
Strikeshield





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  #18  
Old 04-23-2003
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Lightning Anyone?

I have been reading the thread on lightning protection with great interest and am amazed at the amount of misconceptions about the whole thing. Especially the information on lightning "prevention" systems or static dissipaters.
I think that it is safe to say that the information is wide ranging and confusing.
A few things are sure however, and need to be reiterated for the benefit of people wondering.
First of all there is no such thing as attracting a strike. Some individuals think that because they have the tallest mast in a marina that they are more susceptible to a strike or that installing a ground to the mast will increase the likelyhood of a strike. That is simply not true.
Secondly, there is no such thing as preventing a strike. Static dissipaters have been scientificially questioned by the IEEE and there are several papers written by scientific authorities documenting this. Two that are worth reading are:

http://www.strikeshield.com/Lightning%20info/mousaIEEEDissipators.pdf
This first paper was written as a result of a comprehensive study done for British Columbia Hydro on the effectiveness of static dissipaters. Dr. Moussa relied heavily on US data from NASA, the FAA and other scientific authorities.
and
http://www.thomson.ece.ufl.edu/lightning/IEEE.pdf
This paper written by the eminent Dr. Ewan Thomson of the university of Florida basically criticized the ABYC for recommending "seriously inadequate" measures for lightning protection.

All of the lightning authorities agree that there is only one solution to this problem and that is to properly ground ANY structure that is susceptible to a lightning strike and this includes boats. The problem for sailors is that most boat manufacturers DO NOT abide by the ABYC standards which recommend the installation of properly sized conductors to ground lightning energy from the mast to the water.
What are we left with ? Unprotected boats, improperly jury-rigged grounding devices such as chains and booster cables and complete confusion as to what to do.

A few important areas require attention of one is to create a lightning protection system;
Material selection and assembly procedures are quintessential to the success of such systems.
I shudder when I hear of people clamping booster cables to the stays of their sailboats. This is so dangerous !
The cable connectors are improperly sized and offer little contact surface. The result is an exploding vaporized copper clamp.
Using chains wrapped around masts is equally dangerous. The links are highly resistive and can overheat and melt the roof or set it on fire.
This has happened time and time again and yet people still believe that this is an acceptable solution. It is not.

Conductors must be properly sized. Nothing less than a 1/0 multi-stranded tinned copper marine shipboard cable should be used.
Wires must be connected using proper lugs that should be swaged onto the wire with an industrial hydraulic press. The connections should be tinned and then protected with a heat shrink. These methodologies and assembly techniques are used in the power industry. There are UL, ISO, ASTM and IEEE standards with respect to the use of cables for conducting power and they are the result of extensive testing and experience.These methods are the only acceptable methods of building such a system. Hardware store household No.4 wire saddle clamps are inadequate for marine applications.
Electrical connection to the mast must be made through a large contact area. Small clamps and screws or bolts are inadequate for sustaining multiple strikes. Copper parts and components should be tinned for corrosion resistance and to prevent galvanic reactions.
All parts used in the creation of such a system MUST be copper. Not Monel, Not Bronze, Not Stainless Steel or any other less conductive metal. Choosing materials other than copper only adds resistivity to the ground circuit which will cause this material to overheat. This principle is used in electric stoves. Steel wires with high current running through them turn red hot. Same thing will happen to these resistive metals if lightning energy comes through them.
Bonding Bronze Throughulls to the lightning ground is another good method of ensuring the boat sinks in the event of a strike. If the throughulls have lightning energy running through them, the current passing through will heat them up to the point where they may melt the surrounding fiberglass and pop out. Then you will have much more serious problems.
Finally the dissipation electrode in contact with water must be copper (tinned) and offer a large amount of edges as electrical energy will contact with water much more freely through edges than flat areas.

Chris L.
Strikeshield





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  #19  
Old 04-24-2003
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Lightning Anyone?

Chris:
Well said!!!
Gord
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  #20  
Old 02-26-2005
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Lightning Anyone?

in your message you refer to tinned copper as the only substance to take a lightning strike without failure, but what I ask is how is lightning diferent than a spark in a sparkplug and why could you not concider a material with as little resistance as carbon fiber ( the conductor in spark plug wires) if the bonding were to use a carbon fiber conductor you wouldn''t have a problem with excesive voltage heating up the conductor, but your worry would be only the conecton to the mast/rigging and to the grounding plate. please share your thoughts
joey
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