For immediate release
Contact Ewen Thomson, Marine Lightning Protection Inc.
EwenT@marinelightning.com Tel. 352-373-3485
www.marinelightning.com
Frequently Asked Questions
Q. Where in the
Thomson:
Wherever there is any possibility that it could get struck by
lightning. No one who has ever been there would dispute the threat posed
by lightning to boaters in
Q. What actually happens when lightning kills or injures people aboard a boat?
Thomson: Research shows that boaters die when current flows through the brain causing cardiopulmonary arrest. . Not all lightning victims die, of course. Besides burns and hemorrhaging, survivors initially may suffer headaches, ringing in the ears, dizziness, nausea, vomiting and seizures. Lingering disabilities include depression, personality change, memory loss, difficulty processing information and impotence.
Q. How does your lightning protection system help prevent injuries and death?
Thomson: It provides conducting paths for the lightning current to follow. The novel aspect of our system is that the paths, that is, the lightning conductors, are routed near the outside of the vessel. This network of external conductors tends to shield the inside of the boat thereby protecting people and gear on board.
Q. Has your system ever been tested?
Thomson: Tests of our patented Siedarc electrodes were conducted in which we generated sparks to both seawater and fresh water. The spark patterns indicated that it is more effective to place the electrodes just above the water surface than just below. That’s how we arrived at the optimal location for those electrodes, which are, by the way, the cornerstone of our system. These Siedarc electrodes are designed to the same specification (1/2 inch diameter) as a lightning air terminal (a lightning rod) even though they are expected to conduct much less current because the load is shared amongst them.
Q. What kind of hardware does the system require?
Thomson: Starting from the deck and above, we mount air terminals (lightning rods) preferentially around the perimeter. The function of these is to intercept the main lightning channel. Connected to the air terminals is a network of horizontal and vertical No. 2 gauge cables that perform two functions: 1. They conduct the lightning current down from the air terminals towards the water, and 2. They form a conducting shield that is facilitated by least one loop at deck level.
The grounding system comprises multiple conductors whose function is to dissipate the lightning charge into the water. There are two types: 1. An immersed one square foot grounding strip, the GStrip, forms a conductive path directly into the water. In the trawler John Henry it is placed at the stern of the boat with all interconnections in a watertight lazarette. 2. Six Siedarc electrodes are evenly spread around the hull just above the waterline. The function of these is to form sparking connections into the water to both provide multiple exit points and lower the risk of potentially deadly sideflashes from other shipboard conducting fittings.
Q. What exactly do you mean by a sideflash?
Thomson: You will often hear me use “sideflash” and “spark” interchangeably. The word spark, as we commonly think of it, sounds pretty benign, but that’s not the case when we are talking about lightning. These sparks or sideflashes involve voltages of tens to hundreds of thousands of volts.Q. Does your system require that a boat be "bonded?"
Thomson: Bonding is highly desirable, but not the way we commonly think of bonding in boats. In compliance with ABYC standard E11, we make one connection between the DC negative ground bus and the lightning conductors. Hence each electronics system on the DC bus has its ground side “bonded” to the lightning protection system. Because there is already an onboard connection to the AC ground, the same is true for any AC system. The intention of bonding conducting fittings to the lightning protection system is to equalize potentials, or voltages. If all conductors are at the same voltage then sparks, which require voltage differences, are eliminated.
However, this is where we differ from typical notions about
bonding. Bonding connections also increase the risk of sideflashes
to the water, particularly for fittings near the water. So there is
always a compromise between lowering the risk of internal sparks and increasing
that of external sideflashes. In particular, it
is better if a boat does not have all underwater fittings such as thru-hulls
bonded since because bonding wires introduce more opportunities for sideflashes to the water.
Q. If bonding wires actually
increase the risk of damage, is there some other way to "equalize
potentials?”
Thomson: Many people have heard
of the “Faraday Cage.” This is a completely enclosed conductor that
shields anything inside. This means that any conductor inside the cage is
at the same voltage as the cage, no matter what the voltage of the cage
actually is. Our lighting protection system approximates a Faraday cage by
making certain that all of the lightning conductors are outside vulnerable
conductors on the boat, including her human crew and electronic equipment. This
is how we reduce the risk of dangerous internal sparks.
Q. So you’re saying that your system will protect ship's electronics from lightning damage as well as the ship’s crew?
Thomson: In
the lightning business "will" is a word we try not to use. To
quote the National Fire Protection Association: "Lightning is a
stochastic, if not capricious, natural process. Its behavior is not yet
completely understood.” In other words, we, meaning the whole lightning
protection industry, do the best we can but do not predict outcomes, and there
are no guarantees. Indeed, the word "protection" is somewhat of
a misnomer. A better word would be "mitigation" as the
objective is to reduce the severity of damage or likelihood of injury.
Back to the question, electronics systems on ships are comprised of multiple
conducting parts, that may extend over the whole vessel, with various devices that
develop voltages, typically 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.
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.
Q. Does lightning protection work in fresh water, too?
Thomson: Any
system is likely to work less effectively in fresh water. Since fresh
water is much worse as a conductor than salt water the
voltages developed on the boat are much higher and the risk of sideflashes hence much larger. So in fresh water it is
even more important that there are multiple grounding points that are
distributed around the hull. In particular, in my peer reviewed IEEE (
Q. Down on
the docks, I had heard that a lightning protection system actually attracts
lightning by providing a convenient path to ground. Is that true?
Thomson:
Absolutely not. A common, and dangerous,
misconception is that an ungrounded mast is less likely to get struck than one
that is grounded. It is dangerous because this is frequently given as a
good reason to leave a boat with no protection system. The point was addressed
in a
Q. Is it true multi-hulls are more susceptible to lightning strikes than monohulls? If so, why is that?
Thomson: Yes,
they appear to be twice as susceptible based on Boat
Q. What was the role of Mirage Manufacturing in the development of Marine Lightning Protection products?
Thomson: There has always been a close collaboration between Mirage and MLP. While we have been developing the Siedarc line of sparking electrodes, Mirage President Ken Fickett has acted as a sounding board, helped out with the prototype development, and given pragmatic advice from the point of view of the boat builder. During the installation on John Henry, Mirage engineer Bill Wilcox tackled the very difficult job of routing the lightning cables and making the interconnections. For example, when connecting a tinned copper wire to an aluminum handrail it is imperative to take account of the potential for galvanic corrosion.
Q. What does it cost for a Marine Lightning Protection system?
Thomson: It depends. We sell Siedarc electrodes for $140 to $370 each, depending on how the cable is attached to each one. The typical installation uses six electrodes. The GStrip immersed grounding strip is $400, including an oversize copper connecting stud and installation hardware. All of our products are made of tinned copper.
Much of the installation or retrofitting costs will depend
on the size and complexity of the vessel as well as the existence of structures
that could seriously compromise the system such as carbon fiber fittings, and those that can be used as a part of the
system, such as handrails, arches, and bimini
tops.
For example, the six electrodes and one GStrip
in John Henry cost about $2,300. An additional
$800 in materials, such as cable, connectors, air terminals, and
customized fittings was needed to complete the system, for a total of about
$3,100 for hardware. Labor time and costs for installation vary widely from
boat to boat and can be expected to be much higher for a retrofit compared with
a new build.
Q. Some boat manufacturers believe that their liability in the event of lightning casualties is actually less if they refuse to install lightning protection in their boats. Is this true?
Thomson: No There is a belief amongst some manufacturers that if they install a lightning protection system that then fails they are more liable than if they had done nothing at all. There is no obligation to install a system because existing standards are not mandatory and are intended mainly to improve personal safety, not assure it. However, there is solid evidence that even perfunctory adherence, such as grounding a mast to keel bolts, decreases damage. Hence this argument would tend to fail the "due diligence" requirement. Gary Crist, a lawyer, addresses this argument in "When lightning strikes" published in the April 1996 Golf Course Management, writing, "Many people incorrectly believe that liability is best avoided by doing nothing. Those who assert this illogical argument believe their approach disassociates them from the hazard, rendering them not responsible for any resulting damage or injury. Such thinking is legally incorrect, to say nothing of its utter insensitivity." While Dr. Crist was referring to lightning hazards on golf courses, the same reasoning applies to lightning protection of boats.
In the context of lightning and yachts, it would seem that a lightning protection system is a reasonable measure to take to ensure the safety of all on board. Perhaps the best argument against the do-nothing approach is that liability claims only follow after costly damage or injury and the best way to minimize the risk of these is to install the best system possible.
Q. Can I reduce my insurance premium by installing a Marine Lightning Protection system?
Thomson: Not yet. We are breaking new ground with our system so it may be some time before the conservative insurance industry catches up with our technology. We hope that as our system becomes more commonplace, insurers will have a track record on which to base premium reductions. In the meantime, some boaters may be sufficiently comfortable with our system to choose policies with higher deductibles, thus reducing premiums in that way.