For immediate release
Note to editors: Ewen Thomson
of Marine Lightning Protection will be available for interviews aboard the
Contact Ewen Thomson, Marine Lightning Protection Inc.
EwenT@marinelightning.com Tel. 352-373-3485
(See included as separate files: FAQ, Lightning Facts, Ewen Thomson CV and Thomson IEEE paper. Also included are explanatory photo graphics and photos of Ewen Thomson. Additional photography is available on request.)
“And he said unto them, I beheld Satan and he was
lightning falling from heaven.”
—from the New Testament, St. Luke 10.18
Ewen M. Thomson, PhD, is the
founder of Marine Lightning Protection Inc. Thomson has spent a career
researching lightning, with a focus in the last 20 years on its effects on all
types of vessels—power and sail; fiberglass, wood or metal; large and small.
During his tenure as a researcher and associate professor at the
Thomson,
an electrical engineer originally from New Zealand, did not find the need to
combine work and pleasure until 1986 when he took up residence in Florida, the
lightning capital of the United States, and purchased a trailerable
sailboat.
"Of
course it comes with lightning protection?" he inquired of the
manufacturer. The answer almost ended this relationship on the spot: “No,
lightning protection just increases the chance of being struck and increases my
liability. It’s better to do nothing than attempt a fix that might not
work.”
The manufacturer was Ken Fickett
of Mirage Manufacturing, whose company now builds the
The system works by creating, in effect, a “Faraday cage” around the boat and its occupants. This is named after inventor Michael Faraday who in 1836 discovered that an enclosure of conducting materials shielded its contents from electrical effects, a finding that can be used to protect against lightning.
Starting from the top of the vessel, Thomson’s system uses one or more air terminals (lightning rods) attached to other system components with heavy gauge cable. Typically Thomson looks for existing metal structures such as a bimini frame and deck rails on a powerboat or the metal bow and stern pulpits or toe rails on sailboats. Ideally these structural conductors are as far outboard as possible. The conductors make at least one circuit around the outside of the boat and are then connected to a series of patented “Siedarcs,” developed by Marine Lightning Protection.
Siedarcs are electrodes made of copper rod, honed to a point and potted with epoxy in an ISO 150/188 compliant thru-hull fitting, installed at intervals just above the waterline. On John Henry, for example, there are six Siedarcs. Thomson developed the Siedarc after his research showed that the area just above the waterline was where vessels frequently suffered damage from lightning “sideflashes.” Sideflashes are sparks carrying hundreds of thousands of volts of electricity, which cause damage, injury, and possibly death.
“If lightning can be thought of as having a preference,” Thomson said, “that preference is to escape from a vessel at or near the waterline. By yielding to lightning’s natural tendencies, our system can minimize dangerous sideflashes. The development of the Siedarc is one of the revolutionary features of our system.”
Like the air terminals that appear to be part of a modern yacht’s antenna array, Siedarcs are similarly unobtrusive, with only the flange of the thru-hull extending out from the vessels topsides, and can even be faired flush with the hull.
Moving into the boat’s bilges the system is bonded to a one-foot square plate at the bottom of the vessel, this being the so-called grounding plate typical of lightning protection systems of the past. However, this by itself is not up to the job. Without incorporating additional measures such Siedarcs that have been developed in the interim, Thomson wrote in his groundbreaking 1991 academic paper, such a ground plate alone was “hopelessly inadequate” in dissipating lightning in fresh water.
Thomson said such a system is the best possible way to protect people aboard boats during a lightning storm, but it can also provide a measure of protection to marine electronics.
“Electronics systems on ships are comprised of multiple conducting parts, that may extend over the whole vessel, with various devices that develop voltages, typically up to a few volts, and currents, typically microamperes to amperes. Lightning, on the other hand, has sufficient voltage to form a spark several miles long, perhaps 100 million volts, and conducts peak currents of the order of tens of thousands of amperes. It only takes a small fraction of either of these to get added into an electronic circuit to destroy it. So the task is daunting,” Thomson said.
“However, much can be done to lower the risk. If the lightning attaches to an air terminal, flows through the lightning protection system around the boat, and exits at the outside of the hull, then there is less chance for the current to divert into wiring. Also, if the lightning protection system forms a shield around all electronics systems, including wiring, then there is less chance for voltage differences to develop between wires or electronic components. We design the system with these factors in mind.”
Marine Lightning Protection manufactures and sells the
hardware involved in its system, charging $140 to $370 for each Siedarc depending on the connector required and $400 for
its GStrip grounding plate. Cable connection costs
add to the bill for hardware, but the bulk of the cost of installing the system
is due to labor costs.
Besides John Henry, Marine Lightning Protection systems
using Siedarcs have been installed in two sailing
vessels during construction—the record-breaking
“For most vessels, a Marine Lightning Protection system can be installed for less than the cost of installing a bow thruster. We believe that’s a small price to pay to protect your friends and family,” Thomson said. “To paraphrase my fellow New Zealander, quoted at the top of this news release, boating is often the business of navigating under random skies during lightning storms. Any prudent mariner would choose the most robust defense possible if there were science to back it up. We now have that science.”
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