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  #21  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by noelex77 View Post
The consensus is that grounding slightly reduces the chance of strike.

Grounding reduces the charges that can accumulate at the masthead and attract the lightning.
The effect, however, is very small. The only real practical effect is to reduce the damage.
Thats the direct masthead strike, we were hit by a side strike through the water. I agree, trying to prevent a strike may not be possible, Trying to minimize damage...not sure that works either, though I believe its important to give the lightning a path or two to exit or it will blow holes in things to find its way to exit. The question is can you really direct the exit or path of the elkctricity once its on board, or will it seeks its own path off depending where it entered.
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  #22  
Old 01-20-2013
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Re: lightning advice

If you really want to know, get in touch with Dr. Uman at the University of Florida lightning research lab. ECE-UF Dr. Martin Uman

He is pretty much the expert in lightning protection engineering in the world from what I understand, though I have never dealt with him directly.
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  #23  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by Maine Sail View Post
Amen!!
Maine,

I am not saying not to have an effective way of grounding at all. I have it and had it and was still struck by lightning. I can still see the big flash inside my boat this summer when the bolt hit. This dispite a dynaplate grounding system and a burr dissapator on the mast head. I am no more afraid of a lightning strike now then I was before last summer, although I dont want to go through the experience again. They only way to prevent that is to stop sailing ( fat chance)

I respectfully disagree that you can prevent your boat from being struck or even direct the lightning without physical proof.

Do you have knowledge that having extensive lightening protection system on the boat other than basic grounding to the engine or a dynaplate is effective and will cause the lightening to follow that path andc minimize damage?

Most I have talked to including the most respected electric. electronics person here in Annapolis says you can waste thousands of dollars integrating this, but it is no gaurentee and there is not real data which indicates that the electricity from a strike, or side strike can be effecively DIRECTED to a SPECIFIC path.

He beleives in providing one or two ways of grounding as this may be one of paths the elctricity will follow and it would foolish not to at least provide a path and have things grounded.

He also beleives there is no proof that you can protect your boat from being struck other than to minimize where it is physically, nothing you can include on the boat which will act as a force field to shun the strike or to attract or not attract it.

If you have this knowledge share it so I and others can install it on or boats.

Surely if this works maybe we can convince the insurance companies to lower our policies, if we install these measures as we are less likely to have damage and if we do it will be less expensive to them.
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Last edited by chef2sail; 01-20-2013 at 03:57 PM.
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  #24  
Old 01-20-2013
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Re: lightning advice

Lightning is unpredictable, but still follows the laws of physics. If you can provide a good straight low resistance path to ground there is a good chance this is where the pulse will go.
This prevents the most severe damage which can occur when the energy exits the hull via a metal fitting such a seacock or chainplate. In the former case the reasonable chance the boat will sink in the later that the mast will fall down.

Grounding is not a guarantee that this is where the energy will go, but with a well made ground system it there is a very good chance that is where all, or most of the energy will be diverted to.

Grounding is best defence you have. It significantly reduces damage, particularly the severe damage that can mean loss of the vessel and / or lives.

However it does not:
Significantly reduce the chance of a strike
Mean you will have no damage
Guarantee you won't suffer severe damage.
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  #25  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by Stumble View Post
If you really want to know, get in touch with Dr. Uman at the University of Florida lightning research lab. ECE-UF Dr. Martin Uman

He is pretty much the expert in lightning protection engineering in the world from what I understand, though I have never dealt with him directly.
Another expert is Roger R. Block, co-founder of PolyPhaser Corporation, who has done a great deal of work protecting very expensive and one-off gear for the military and three letter initial companies inside the beltway. Extensive testing and validation and his works are available on the net. He has retired for the most part, but his devices and protection plans are second to none.

YMMV
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  #26  
Old 01-20-2013
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Re: lightning advice

Interesting points discussed here. I was thinking of a lot of the suggestions while in a lightning storm for 5 hrs last August 300 miles west of San Francisco.

I resorted to loud singing and it worked. I did not get hit but I did have a sore throat the next day.

Neal
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  #27  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by kd3pc View Post
Another expert is Roger R. Block, co-founder of PolyPhaser Corporation, who has done a great deal of work protecting very expensive and one-off gear for the military and three letter initial companies inside the beltway. Extensive testing and validation and his works are available on the net. He has retired for the most part, but his devices and protection plans are second to none.

YMMV
Ok I have read some of Blocks stuff and all seem related to antannnaes and ground communication stations etc, Maybe you could steer me to the specificdata and information on sailing vessels or boats in the water as I dfo nolt seem to be able to find this.

What kind of Robert Block methods have you emplyed on Tango to minimize lightening strike effects other than a simple grounding to a plate or the engine?

Would like to learn some other best practices as I have that on my boat already and that had NO effect.

Dave

Dave
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  #28  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by Stumble View Post
If you really want to know, get in touch with Dr. Uman at the University of Florida lightning research lab. ECE-UF Dr. Martin Uman

He is pretty much the expert in lightning protection engineering in the world from what I understand, though I have never dealt with him directly.
Do you have any specific information as it pertains to boats or sailing information other than general lightening protection which he is an expert on.

I dont need to read about the theory I undestand it. Specific data is what I am looking for.
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  #29  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by noelex77 View Post
Lightning is unpredictable, but still follows the laws of physics. If you can provide a good straight low resistance path to ground there is a good chance this is where the pulse will go.
This prevents the most severe damage which can occur when the energy exits the hull via a metal fitting such a seacock or chainplate. In the former case the reasonable chance the boat will sink in the later that the mast will fall down.

Grounding is not a guarantee that this is where the energy will go, but with a well made ground system it there is a very good chance that is where all, or most of the energy will be diverted to.

Grounding is best defence you have. It significantly reduces damage, particularly the severe damage that can mean loss of the vessel and / or lives.

However it does not:
Significantly reduce the chance of a strike
Mean you will have no damage
Guarantee you won't suffer severe damage.
Quote:
This prevents the most severe damage which can occur when the energy exits the hull via a metal fitting such a seacock or chainplate. In the former case the reasonable chance the boat will sink in the later that the mast will fall down.
So what is your system on your boat other than a ground plate and an egine ground?

Quote:
Grounding is not a guarantee that this is where the energy will go, but with a well made ground system it there is a very good chance that is where all, or most of the energy will be diverted to.
This is saying nothing saying I am not sure where the energy will go, but if it there is a ground system there is a good chance where the energy will go but maybe n ot all of it. Not a scientific or even a reassuring statement

Quote:
Grounding is best defence you have. It significantly reduces damage, particularly the severe damage that can mean loss of the vessel and / or lives.
No its the only defense you have and the rest of the statement isnt true as you cant evebn gaurentee thats where the enrgy wil go. And where does this statement about loss of lives come from. Best way to prevent that is to be off the boat....not grounded.

Come on now, I can undertand the physics of lightening like most can. I can read the same experts. Coomon sense tells me it will search for the path of lerast resisitance or shortest path and thatits important to provide it with one or it will make one.

Common sense also tells me that people who try and make thousands of dollars off of this fear when they cannot prove or will not gaurentee their expensive products work are a sham.

These statements are a false sense of secutity when there is not gaurentees that your theory will work. It allows the snake oil salesman to create all sorts of diffusers and bonding/ grounding systems which cost thousands when there is no proof or gaurentee. Even the insurance companies see no value in this pr they wouild give people discounts. Its sheer speculation

The best you can do is ground evrything to a plate, give it a path...something which doesnt cost a lot of money and pray the lightning travels that path and doesnt seek an alternative.
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  #30  
Old 01-20-2013
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Re: lightning advice

Quote:
Originally Posted by chef2sail View Post
Ok I have read some of Blocks stuff and all seem related to antannnaes and ground communication stations etc, Maybe you could steer me to the specificdata and information on sailing vessels or boats in the water as I dfo nolt seem to be able to find this.

What kind of Robert Block methods have you emplyed on Tango to minimize lightening strike effects other than a simple grounding to a plate or the engine?

Would like to learn some other best practices as I have that on my boat already and that had NO effect.

Dave

Dave
for me, Block has good information on grounds, grounding and grounded items, as well as details about connections, especially mechanical ones, attachments and what measurements to expect to survive a hit, direct or otherwise. The concepts of very shallow bends in grounding conductors, size and materials of conductors and the theory that EVERYTHING must be at the same ground potential, ie 2.5 ohms or less to every item grounded appeals to me, he advocates against "old school" theories like concentric rings of grounds as they create loops and multiple paths.
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