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Marine Lightning Protection

About us


Marine Lightning Protection Inc. (MLP )  specializes in lightning grounding in the marine environment. Improving on existing standards such as ABYC TE4, ISO 10134 and NFPA 780 Ch. 8 (pre-2008), we emphasize the grounding system since this is the foundation for any boat lightning protection system. In order to integrate superior grounding into a complete system, we also offer other components such as air terminals, connectors and main conductors.

In the not-too-distant past, standards were of limited value since they advocated a single one square foot ground strip or plate and a centrally located down conductor, a concept that was incompatible with the science that was established more than a decade ago. Specifically, in a paper published in a peer reviewed IEEE journal in 1991, Dr. Ewen Thomson of the University of Florida concluded that "1 ft2 is shown to be hopelessly inadequate to prevent sideflashes in fresh water". As Thomson points out, the key to reducing sideflash likelihood is to distribute the lightning current into the water from multiple sources. Since using multiple immersed ground plates is impractical, and the optimum location for exit terminals is close to the waterline, MLP has developed the new patented SiedarcTM electrodes that can be faired into the hull to reduce drag and require only a single hull penetration. Further, they are preferably installed above the waterline, thereby eliminating galvanic corrosion.

The lightning system

The typical lightning protection system is built as follows. Starting with multiple grounding electrodes distributed around the hull's perimeter, we then connect a network of down conductors that form a protective rib cage around the sensitive interior of the boat. Bonding conductors are also attached to this to equalize potentials throughout the boat. A key component is a loop conductor at about deck level that both forms an electrostatic shield and is used for bonding connections. Note that shielding by means of external conductors is an effective way to equalize potentials and is the only method that can be used for conductors such as water tanks and crew members that cannot be bonded with connecting wires. In this way we equalize potentials inside the boat to reduce sideflash likelihood. At the top of the lightning protection system are the air terminals, the desired attachment points for the lightning channel. On a powerboat, existing conducting fittings such as handrails, outriggers, T-tops, biminis, and metallic superstructures form an integral part of this system. Since we already have a network of down conductors that are predominantly near the outside of the hull, the natural location for air terminals is also around the perimeter.

The net result is a boat lightning protection system that closely resembles that on a building – air terminals around the roof perimeter, multiple down conductors on the outside, and multiple ground rods outside the footings These concepts have now been incorporated in the latest standard (NFPA780-2008, Chapter 8) published by the National Fire Protection Association. In addition to a whole range of lightning protection products, we also offer consulting services regarding any scientific or technical aspect of lightning in the marine environment, including lightning protection systems, lightning damage, insurance disputes and litigation. Design guidance in accordance with the new NFPA780 standard are also provided at reasonable rates.


Despite being a sailor and lightning researcher for many years before, MLP  founder and native New Zealander Dr. Ewen Thomson did not find the need to combine work and pleasure until 1986 when, while an Associate Professor in Electrical Engineering at the University of Florida, he purchased a trailerable sailboat from a local builder.  "Of course it comes with lightning protection?" he inquired of the manufacturer when the deal was nearly made.  The answer almost, but not quite, ended this relationship on the spot - "No, lightning protection just increases the chance of being struck and increases my liability.  It is better to do nothing than attempt a fix that might not work." The manufacturer was Ken Fickett, CEO of Mirage Manufacturing. who now builds the Great Harbour line of passagemakers and has continued collaborating closely with MLP. In fact, the first MLP system was installed in a Great Harbour 47. Needless to say, Ken is now a firm believer in lightning protection systems for his passagemakers.  When faced with personally sailing a 19 foot boat in capricious Florida weather, Ewen was highly motivated to install the best system that technology would allow.  So he looked up the existing codes published by ABYC (American Boating and Yachting Council) and NFPA (National Fire Protection Association), talked to some colleagues at the University of Florida, reviewed the scientific literature, did a few calculations, and requested damage reports from sailors who had had the misfortune of being inadvertent data gatherers.  The results were surprising, worthy of publication in a professional journal, and filtered into the standards.  Further work was funded by Florida Sea Grant to answer the key question of whether lightning protection does indeed increase the probability of a strike (the answer is NO),  and to generate some materials that would be useful for the layman.  Consequently in 1992 he wrote a Sea Grant pamphlet and co-produced a 23 minute video  to communicate the science of lightning protection to the general public.

While the science of 1992 was good enough to reveal some holes in the lightning protection standards, it did not explain everything.  During a sabbatical in 2000-2001, Ewen revisited some of the more perplexing observations that could not be explained a decade before.  After this decade of reflection, he finally realized that the scientific theories he, and others, had used previously were incomplete.  A more complete theory could indeed explain the more puzzling data.  This theory also made possible a new device for grounding, the SiedarcTM electrode, which, in turn, can be integrated into a far more comprehensive lightning protection system comprising a network of external conductors, just as in a building. And, in a major departure from the ineffective status quo, NFPA-2008 now addresses the earlier concerns.   Marine Lightning Protection Inc. was founded in May 2001 as a commercial vehicle for supporting the design, fabrication and installation of grounding components and  systems using this new technology.  Founder Ewen Thomson is MLP's president and resident consultant. Since lightning protection frequently requires consideration on a case-by-case basis,  MLP hence offers the expertise and experience needed to provide grounding products and system design for all customized applications. 


Our better understanding of the underlying science is now augmented by the NFPA standard that translates this science into engineering specifications. The arguments for installing a comprehensive lightning protection system have never been more compelling. Nor have they ever been more easy to understand – simply design the system using the same ideas as are used on buildings. With the dramatic shift in the marine industry to microprocessor-controlled equipment, including power and steering controls, and the ever-present liability concerns, an effective lightning protection system should be regarded as a practical and necessary insurance policy, both for the customer and the builder. With international patents protecting our intellectual property and customers in the United States, Chile, New Zealand, Australia, Canada, England, Costa Rica, and South Africa, MLP is committed to a pivotal position in the global marketplace. We are particularly interested in working with yacht manufacturers in any country to develop designs and best practices for installing systems at the most cost-effective and convenient time – during manufacture.


Marine Lightning Protection Inc.

3215 NW 17th Street
Florida 32605
Please call or email if you have any questions.