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Old 12-03-2009, 15:20   #16
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OK, "Bottle brush" dissipaters are now to be called Evaporative Lightning Rods, or ELRs, because they completely disappear upon a strike, which they have possibly been proven to not protect against. Properly installed lighting rods at mast top will channel lightning down wire and out grounding plate mounted below waterline while aiding EMF pulse to wipe out every electronic device onboard and not stowed in oven. And ALL of this has NOTHING to do with bonding thruhulls and shafts!

While on my first ICW cruise several years ago, I was horrified to hear that a sailor was killed when his boat was stuck by lightning a week before I arrived at a Florida port. I was even more scared when I found out that his mast was DOWN and mounted across his deck to allow for over ground shipping! I have always been told that the cure for sea sickness is sitting under a tree. Except during a thunderstorm!
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Old 13-03-2009, 03:41   #17
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Quote:
Originally Posted by s/v Jedi View Post
Gord,
... I read all the links you provided for reference and didn't find any evidence supporting this statement of you. Pls. provide better links :-)
Note: My objection is limited to the claims made for & about "dissipation".
I heartily endorse the use of grounded lightning rods (electrodes).

Here’s some links to a few of the expert opinions & papers I’ve previously cited:

A CRITICAL REVIEW OF NONCONVENTIONAL APPROACHES TO LIGHTNING
PROTECTION
~ BY M. A. UMAN AND V. A. RAKOV
MARTIN A. UMAN, Distinguished Professor: ECE-UF Dr. Martin Uman
http://www.lightningsafety.com/nlsi_lhm/Uman_Rakov.pdf

WAR OF THE LIGHTNING RODS ~ By Abdul M. Mousa, (Ph.D., P.Eng., Fellow IEEE)
http://www.lightningsafetyalliance.c...htning_war.pdf

There Is No Magic To Lightning Protection:
Charge Transfer Systems Do Not Prevent Lightning Strikes
~ William Rison
(Professor of Electrical Engineering, New Mexico Institute of Mining and Technology)
”... The principles of traditional lightning protection are basic — 1) provide preferential strikes point for lightning (an array of conductors higher than the objects being protected), a good grounding system, and conductors between the two to conduct the damaging current from a lightning discharge away from the structure to be protected; and 2) provide appropriate transient protection on power and signal wires entering the structure to protect equipment and personnel from the effects of induced lightning currents ...
http://www.lightningsafety.com/nlsi_lhm/magic.pdf

Charge Transfer System is Wishful Thinking, Not Science ~ Charles B. Moore*
(Professor Emeritus, Atmospheric Physics, New Mexico Institute of Mining and Technology)
Charge Transfer System is Wishful Thinking, Not Science - National Lightning Safety Institute

*Charles B. Moore is internationally known for his research on the electrical aspects of thunderstorms and volcanoes. He is an expert in many different areas of atmospheric research, including the scientific and political aspects of weather modification, the scientific and practical issues of lightning protection, and the efficacy of different kinds of lightning rods:
Lightning and Thunderstorm Research - Langmuir Laboratory
http://infohost.nmt.edu/mainpage/news/2005/7feb02.html



Fundamentals of Lightning Protection ~ By Richard Kithil, President & CEO, NLSI*
*National Lightning Institute
Fundamentals of Lightning Protection - National Lightning Safety Institute

Evaluation of Early Streamer Emission Air Terminals ~ By Scott D. McIvor, Roy B. Carpenter, Jr., Mark M. Drabkin, Ph.D.
...”CONCLUSIONS: There is limited test data on ESE performance, and no available data substantiates the suppliers’ claims; conversely, the data collected by independent researchers prove otherwise. That is, the ESE performs no better than the conventional Franklin rod.
2. The physics related to the situation, as provided by the atmospherics physics community, demonstrate that the claims made for all of these ESE are wildly exaggerated ...”

http://www.ees-group.co.uk/downloads/ESE%20paper.PDF
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Old 14-03-2009, 18:01   #18
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Ahhhh.....

Okay, after reading all that I start to understand. Manufacturers of devices much like the static dissipaters for boats claimed that they could prevent lightning from occurring and these claims have been proven to be false. I completely agree.

But also: nowhere in these documents, the principle of operation of a static dissipater is questioned: it is considered a proven and demonstrated phenomena; it does however, not prevent a storm cloud from producing lightning.

The next step in thinking in these documents is this: if that lightning is gonna occur anyway, it's just as good to put up a standard lightning rod to "capture" it. And as these work well, it's not worth the extra money for the dissipater systems.

I agree with all of that..... for buildings. But for me on my boat, it's a bit different! I have a standard rod in the form of my mast with antenna's and a good ground connection to the seawater. But I still wish for the lightning to strike somewhere else, as I don't like the damage at the antenna's and other stuff up the mast and from the EM field generated during a strike. I don't wish to try to neutralize the stormcloud, I just wish the strike to occur on another object. And exactly that is something that scientists agree can be done with the device. I don't care if I pay $100 for it and I also don't care if it's not 100% effective!

Also, these documents are based on buildings & structures ashore plus the wish to protect them all. As it is impossible to prevent lightning, it's argued more like it doesn't matter where the strike occurs.

Reading these documents actually strengthened my good feelings about the brushes for boats as we are anchored most of the time with many, many other good targets for strikes around us. I don't mind the little extra camouflage we use, let the strike select that building just next to us or that tree up on the hill or that really high mast over there...

But I do agree with Gord that cruisers should think of a good ground-path from mast to sea first and only then decide to spend that $100 extra or not. I now realize it might be better for Jedi if most boats don't do that ;-)

cheers,
Nick.
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Old 14-03-2009, 22:06   #19
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Fascinating, inconclusive stuff.

Two thoughts:

  • Boats that are plugged-in at dock are grounded in some fashion; the notion of staying completely isolated is not generally acheivable.
  • Boats that find themselves in a thunderstorm have salt all over the deck - again they are not completely isolated.
OK, 3 thoughts:
  • Cats can easily tow a grounding cable - not jumpercables, though. Something long and designed for the purpose. Since the keels and engines are to the sides, a reasonable length down the middle is acheivable. There are systems comercially available.
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Old 14-03-2009, 22:30   #20
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Ok..Back to the issue of bonding or not. I believe in unbonded having tried both for many years. I stopped bonding and noticed longer zinc life and healthier bronze thru-hulls. Calder was of the bonded camp then switched...good enough for me. Also remember grounding is not bonding. Grounding is a different issue as is lightning protection.
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Old 14-03-2009, 22:51   #21
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Celestial: As I wrote before, I agree if thru-hull resistance against galvanic corrosion is the only criteria. However, I can't imagine a situation where that would be applicable, or you must limit sailing to an area that never has any lightning. Also: your experience might have been in an area that does have lightning but it never hit you. In that case no bonding might not have been better but instead you were lucky to never had a strike... if you can follow me. The only real test is if you would have had a direct strike in both scenarios. This is the reverse of our experience: Jedi was hit twice with grounding/bonding system but without damage to the hull in both cases. That doesn't mean we would have had damage to the hull if that grounding system would not have been there... we just don't know, it wasn't "tested".

But your definition of bonding is also grounding because the thru-hull is in the water so provides a path to ground, even if you don't want that, it's there. But that doesn't matter if you don't do either ;-)

Thinwater: plugged in at dock using an isolation transformer blocks ground from shore so that leaves you ungrounded. This is what most aluminium hulled boats do!

Salt on deck: You think lightning would followed the salt-path over deck? It does not because it will not make the 90 degree turn from mast to deck, not even with a deck-stepped insulated mast, but it might follow shrouds and stays instead in that case.

Cats towing grounding cable: I stand corrected: cats can have a well grounded mast! The other way is to ground the capshrouds but that might not work. The thing is that the cat will probably be safe without a grounded mast and the lightning knocking a hole in the deck under the mast. It's above waterlevel. But personal safety is an issue as it could easily arc from mast to nearby person.

cheers,
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Old 15-03-2009, 00:54   #22
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Originally Posted by s/v Jedi View Post
Celestial: As I wrote before, I agree if thru-hull resistance against galvanic corrosion is the only criteria. However, I can't imagine a situation where that would be applicable, or you must limit sailing to an area that never has any lightning. Also: your experience might have been in an area that does have lightning but it never hit you. In that case no bonding might not have been better but instead you were lucky to never had a strike... if you can follow me. The only real test is if you would have had a direct strike in both scenarios. This is the reverse of our experience: Jedi was hit twice with grounding/bonding system but without damage to the hull in both cases. That doesn't mean we would have had damage to the hull if that grounding system would not have been there... we just don't know, it wasn't "tested".

But your definition of bonding is also grounding because the thru-hull is in the water so provides a path to ground, even if you don't want that, it's there. But that doesn't matter if you don't do either ;-)

Thinwater: plugged in at dock using an isolation transformer blocks ground from shore so that leaves you ungrounded. This is what most aluminium hulled boats do!

Salt on deck: You think lightning would followed the salt-path over deck? It does not because it will not make the 90 degree turn from mast to deck, not even with a deck-stepped insulated mast, but it might follow shrouds and stays instead in that case.

Cats towing grounding cable: I stand corrected: cats can have a well grounded mast! The other way is to ground the capshrouds but that might not work. The thing is that the cat will probably be safe without a grounded mast and the lightning knocking a hole in the deck under the mast. It's above waterlevel. But personal safety is an issue as it could easily arc from mast to nearby person.

cheers,
Nick.
Nick,,,I think you are misunderstanding me. I'm totally into lightning protection and that is allowing a path for a strike to travel. Often times people run the cat whiskers from the top of the mast to a plate through the hull, under. This allows the strike to have a path.
Bonding of the through hulls all together tied to a zinc is what I disagree with which is what I am assuming most posts here are saying also. Bronze being more noble tends to sacrifice the zinc, being less noble. When people, especially electricians use the word "ground", it refers to a A.C. or D.C. system that is grounded to allow a path of return in the case of DC or a safe path for a short circuit in the case of AC. You see it's the choice of words that causes confusion. Sorry for any confusion.
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Old 15-03-2009, 01:41   #23
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My boat has no lightning protection. None at all. I've been struck when underway. As has been mentioned earlier in this hread, lightning followed boat wiring. Anything connected to the wiring was destroyed, anything electronic that's portable survived just fine. Keep this in mind when the thought crosses your mind for an expensive electronic upgrade.

As for the path the lightning took... it exited through my port drive train. I have fixed props with driveshafts.

So, I would say this is a good example of boat design handling lightning without any additional protection.

I was at the helm when we were hit. It was something to see. Photos of the damage to my mast are on my website in the link in my signature.
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Old 15-03-2009, 04:23   #24
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A Glossary of some Grounding & Bonding Terms, as used in the North American Electrical Industry:

Bonding (Bonded):
The permanent joining of metallic parts to form an electrically conductive path that ensures electrical continuity and the capacity to conduct safely any current likely to be imposed.

Ground:
A conducting connection, whether intentional or accidental, between an electrical circuit or equipment and the earth or to some conducting body that serves in place of the earth.

Grounded:
Connected to earth or to some conducting body that serves in place of the earth.

Bonding Jumper System:
The connection between the grounded circuit conductor and the equipment grounding conductor at a separately derived system.

Effective Ground-Fault Current Path:
An intentionally constructed, permanent, low-impedance electrically conductive path designed and intended to carry current under ground-fault conditions from the point of a ground fault on a wiring system to the electrical supply source and that facilitates the operation of the overcurrent protective device.

Ground Fault:
An unintentional, electrically conducting connection between an ungrounded conductor of an electrical circuit and the normally noncurrent-carrying conductors, metallic enclosures, metallic raceways, metallic equipment, or earth.

Ground-Fault Current Path:
An electrically conductive path from the point of a ground fault on a wiring system through normally noncurrent-carrying conductors, equipment, or the earth to the electrical supply source.

Grounding Conductor:
A conductor used to connect equipment or the grounded circuit of a wiring system to a grounding electrode.

Grounding Conductor, Equipment:

The conductor used to connect the noncurrent-carrying metal parts of equipment, raceways, and other enclosures to the system grounded conductor, the grounding electrode conductor, or both, at the service equipment or at the source of a separately derived system.

Grounding Electrode:
A device that establishes an electrical connection to the earth.
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Old 15-03-2009, 07:02   #25
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I'm with Celestrial on this one. I see no reason to bond thru-hulls on a fiberglass boat. They are connected only with hose, and do not present a danger during lightning strike. Proper lightning protection is a wired mast with or without lightning rod or dissipater connected to a submersed ground plate or metal keel. To this you can tie in capshroud chainplates and headstay. On my boat I have a rather unusual arrangement; all four capshrouds on my ketch have a bronze strap bolted to their chainplates which extend below the waterline on the hull exterior. So my mast has FIVE underwater grounds, including the plate. This is all lightning protection stuff. BONDING is another issue entirely, as we are bonding to avoid corrosion. Right now I stand against bonding underwater fittings together. The only question for me now is; since our engine block MUST be grounded to AC and DC ground systems, should I include a conductive strap across my vibration isolating coupler to also ground the propeller shaft and prop? I have zincs on the shaft, plus a large prop nut zinc.

BTW, IMHO the largest danger from lightning strike on a modern sailboat is the knot log and depth sounder transducers. All you can do is have a bung on board, but you have to BE on board to hammer it in...
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Old 15-03-2009, 08:48   #26
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Good points all...

Quote:
Originally Posted by s/v Jedi View Post

Thinwater: plugged in at dock using an isolation transformer blocks ground from shore so that leaves you ungrounded. This is what most aluminium hulled boats do!



cheers,
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However, I have heard of lightening blowing through the transformer, and that was my point. Blows through most things, I gather.

My experience is in refinery exposure to lightening, and as an engineer, I try to remain practical more than theoretical. Even when you don't think there is any ground, what with modifications, one always seems to sneak in. Even if you have a casual ground, a purpose built system is better. Refineries in the plain are real lightening magnets, and for whatever reason, we have learned that with purpose-built grounding systems and multiple rods deep in the ground, we get BOTH fewer strikes and less damage. I have read the theory but I do not claim to know why there are few strikes. There are fewer, in my experience.
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Old 15-03-2009, 09:01   #27
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Why not place though-hulls in their own compartment?

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Originally Posted by Christian Van H View Post

BTW, IMHO the largest danger from lightning strike on a modern sailboat is the knot log and depth sounder transducers. All you can do is have a bung on board, but you have to BE on board to hammer it in...
Good point.

On my delivery trip home (3 days in December, ~ 35F) the PO had miss-installed the knot meter plug (after survey and sea trial) and it leaked a good stream. However, in my boat (PDQ 32) all of the trough-hulls are in separate water tight compartment, with hatch access, just behind the collision compartment. I could have taken the thing out and sailed home carrying an extra 10 gallons of water (it is a small compartment).

That feature also gives solace in the winter, when a through-hull failure is a concern.
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Old 15-03-2009, 09:15   #28
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However, I have heard of lightening blowing through the transformer, and that was my point. Blows through most things, I gather.
Heck, lightning doesn't need to blow through anything. The EMF pulse of a lightning strike can generate enough juice to blow out ANYTHING with circuitry in it. Anything with conductors becomes a generator. A transformer can make juice without being connected to the dock when this much EMF is being tossed around. Anything outside of a Faraday cage is libel to be damaged with a big enough strike. Anyone who has had portable, battery powered stuff survive a strike was just lucky, thats all.
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Old 15-03-2009, 10:53   #29
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Celestial: okay, when you have lightning protection in place you are absolutely right, you might be better off without bonding the thru-hulls.
But, why not use Forespar plastic thru-hulls in that case? They will end all trouble for good. We have both plastic and bronze and after 4 years or so, there's no difference. The plastic ones have a plastic seacock too. I think most negative experiences there are caused by using a valve instead of a seacock. The Forespar plastic seacocks have the flange with mounting holes for fastening it to the hull just like bronze ones. The Forespar valves that turb too difficult have been tightened too much (they are 2 parts so can be dismantled for cleaning/maintenance. The tighter they are assembled, the more difficult it is to operate them with the broken handles as the result. The seacock models don't have that for safety reasons and turn easy.

Tropic cat: okay, but as you say, there is no engineered path for the lightning aboard so no guaranty that the drivetrain is the exit point next time too.

Isolation transformer: Ah, for lightning protection, forget it's there, it plays no role. Also, for a strike ashore resulting to surges on the powergrid, only disconnecting the shorepower cable helps because the surge will enter the boat over hot and neutral wires, not the ground wire.

cheers,
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Old 15-03-2009, 11:09   #30
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Celestial: okay, when you have lightning protection in place you are absolutely right, you might be better off without bonding the thru-hulls.
But, why not use Forespar plastic thru-hulls in that case? They will end all trouble for good. We have both plastic and bronze and after 4 years or so, there's no difference. The plastic ones have a plastic seacock too. I think most negative experiences there are caused by using a valve instead of a seacock. The Forespar plastic seacocks have the flange with mounting holes for fastening it to the hull just like bronze ones. The Forespar valves that turb too difficult have been tightened too much (they are 2 parts so can be dismantled for cleaning/maintenance. The tighter they are assembled, the more difficult it is to operate them with the broken handles as the result. The seacock models don't have that for safety reasons and turn easy.

Tropic cat: okay, but as you say, there is no engineered path for the lightning aboard so no guaranty that the drivetrain is the exit point next time too.

Isolation transformer: Ah, for lightning protection, forget it's there, it plays no role. Also, for a strike ashore resulting to surges on the powergrid, only disconnecting the shorepower cable helps because the surge will enter the boat over hot and neutral wires, not the ground wire.

cheers,
Nick.
Well Nick...I don't use plastic under the water line because...er...uhmmm...I'm old school. Yes...I hate to admit it...I just don't trust them. There I said it! As far as Forespar or RC valves, I've seen both with their plastic handles snapped off after working perfectly for awhile, so I will really pass on them. Also, when I was a toolmaker back in a former life, I was involved in plastic injection molding. Occasionally when a bad patch was made, they were re-ground and re-molded. This weakens the final product...so I'll pass.

GordMay:-Thanks for the definitions. I hope people can see the difference now.
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