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Old 07-12-2011, 08:15   #1
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Lightning Damage Mitigation

Lightning "Mitigation" (bonding) systems work.
Lightning "Prevention" systems do not work.

Seaworthy magazine reviews lightning claims data:
BoatUS.com - Seaworthy Magazine

“There may not be much boaters can do to prevent lightning from striking their vessels, but there is an important step to take immediately after a jolt hits, according to the July 2005 issue of Seaworthy magazine, the quarterly BoatU.S. Marine Insurance and damage avoidance report. In “Lightning! Flash, BANG! Your Boat’s Been Hit – Now What?” Associate Editor Chuck Fort reviews five years of lightning-strike claims data from the BoatU.S. Marine Insurance claims files. What he found might surprise you or confirm your suspicions about lightning strikes.

The feature reports that in any one year the odds of your boat being struck by lightning are about 1.2 in 1,000, with 33 percent of all lightning claims coming from the sunshine state, Florida. The second most struck area in the country is the Chesapeake Bay region (29 percent), while Idaho, Nebraska, and 11 other states had no lightning-related claims.

The rate of lightning strikes for sailboats was about four boats per 1,000, while motorboats averaged 0.5 per 1,000. A surprise finding was that multi-hulled sailboats were struck more than twice as often as monohulls.

Interestingly, the files also showed that many boats equipped with lightning dissipaters were also hit, calling their effectiveness into question. Most electronics aboard a boat, it was noted, were not damaged by a direct hit but rather from surging electrical current created in the wiring by the strike.

While the story explains that some vessels can have little or no damage after a strike, an immediate hull inspection is a must because when lightning exits your boat, it can go through the hull itself or via a through-hull fitting. This may cause a gradual leak that could go unnoticed.

Often, boaters don’t know their unattended vessel has been struck or suffered collateral damage as the result of a nearby strike. The article reviews a claim in which lightning damage was found only after an amber LED light lit up on a battery charger — a light the owner had never seen before — and his depth sounder quit. Sometimes a damaged or missing VHF antenna is the only clue that an unattended boat has been struck. Chuck Fort also mentions that most vessels are not electrically bonded according to the American Boat & Yacht Council lightning protection standards. Boats built to these construction standards offer a more direct pathway for lightning to exit a vessel...”


A little more light reading, on the subject:

NFPA 780 - Report of the Committee on Lightning Protection
http://www.nfpa.org/Assets/Files/PDF/ROP/780-08-ROP.pdf

Lightning & Sailboats (SGEB-17) ~ by Ewen M. Thomson
http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf
SGEB-17/SG071: Lightning & Sailboats

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
Charge Transfer System is Wishful Thinking, Not Science - National Lightning Safety Institute

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*
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

Scientists Oppose Early Streamer Air Terminals ~ By Abdul M. Mousa
Scientists Oppose Early Streamer Air Terminals - National Lightning Safety Institute

Conventional and Un-conventional Lightning Air Terminals: An Overview
by Hartono Zainal Abidin & Robiah Ibrahim
http://www.lightningsafetyalliance.c..._terminals.pdf
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Old 07-12-2011, 08:21   #2
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Re: Lightning Damage Mitigation

Gord, once again, thanks for putting all this research together.
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Old 07-12-2011, 11:37   #3
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Re: Lightning Damage Mitigation

Thanks Gord. Confirms previous reports I have read, especially regarding the ineffectiveness of lightening dissipation systems.

But I do have to question your definition of light reading. I took a class from Martin Uman at UF and there was nothing light about it at all.
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Old 07-12-2011, 11:41   #4
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Re: Lightning Damage Mitigation

Good stuff Gord, thank you.
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Old 08-12-2011, 09:30   #5
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I can only give an opinion on this based off our own exp. While sailing our new boat from kw to tampa we were caught offshore between Marco and kw in one of the worst lightning storms ever. Actualy three storms converged right on top of us and we had strikes hitting the water mulriple times anywhere from 20to 50 ft away , lighting up the water like a pool and we were never hit directly. I was certain we would be I would have bet my life on it. We did indeed have one of those fuzzy dissipators on the mast. Not sure if thats what helped but I feel better with it.
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Old 08-12-2011, 19:03   #6
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Re: Lightning Damage Mitigation

Good info. Thanks.
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Old 09-12-2011, 08:28   #7
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Re: Lightning Damage Mitigation

Quote:
Originally Posted by skipmac View Post
... But I do have to question your definition of light reading. I took a class from Martin Uman at UF and there was nothing light about it at all.
Dr. Uman is generally acknowledged to be one of the world’s leading authorities on lightning.
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