Lightning versus electronics

Lightning is one of nature’s awesome wonders, one that can wreak havoc on your boat and its electronic equipment/systems. Because we are in the middle of the summer thunderstorm season, I thought that now would be a good time to talk about protecting your electronics from the direct and indirect effects of lightning. Modern electronics are very susceptible to the effects of static charges and what is known as electro-static discharge (ESD). ESD can literally fry your electronics. Even more insidiously, sometimes ESD doesn’t completely fry a component, but merely weakens it and causes it to intermittently fail.

         A lightning strike can carry on the order of 100 million volts, have peak currents of tens of thousands of amps, and generate temperatures of some 55,000 degrees Fahrenheit. Fortunately, it lasts only a fraction of a second, but within that time it can be deadly and/or very destructive. Due to the speed and rapidity of change in currents brought about by the lightning bolt, powerful magnetic fields are generated. In other words, lightning strikes can generate a powerful electro-magnetic pulse that can kill your electronics through ESD even if it was not a direct strike. A direct strike, of course, can kill your electronics through physical damage and excessive voltage and currents. This type of damage can usually be eliminated by powering down and unplugging all non-essential electronic devices.

         There have been numerous boats that have taken direct lightning strikes and not only survived, but suffered no damage — not even to the electronics. But these boats all had a properly installed and maintained lightning protection system (LPS). It is beyond the preview of this article to enumerate the minute details of an LPS, however I will mention the three basic elements of such a system. Your boat’s LPS should include four basic elements:

1. An air terminal or lightning rod

2. A robust downlead (at least #4 AWG wire)

3. A grounding plate (at least 1 sq. foot)

4. A perimeter array of grounding, or “exit” terminals otherwise known as bonding.

         Although an LPS should provide your boat a “cone of protection,” it must be understood that according to guidance from the American Boat and Yacht Council (ABYC), that complete protection from equipment damage or personal injury is not guaranteed even by implementation of their new Lightning Protection Standard. This is due to the unpredictable nature of lightning.

         So the first step is to get LPS protection and make sure that all it’s connections are corrosion free, tight, and sealed. Once you have the boat protected then there are a few things you can do to further protect your electronics. The ABYC recommends the use of external shielding to create a Faraday cage around electronics. Whenever possible, electronic equipment should be enclosed in metal cabinets that are connected to the lightning grounding system. Another important way to protect electronics is to use surge suppression devices on all wiring entering or leaving electronic equipment. A poor man’s way to do this is to purchase protected power strips meant for personal computer use and plug your electronics into them.

         In a pinch and your boat lacks a Faraday cage and surge protection devices, it is recommended that you power down all non-essential electronics and unplug them. If they are portable and small enough then put them in a microwave oven that is itself unplugged. The best way to save your electronics is to try and stay out of any thunderstorms by staying in port or navigating around them. One other thing, never use your VHF radio or any other radio during a thunderstorm unless it is an absolute emergency! 


About the Author:

Fredrick Gary Hareland holds an AAS degree in rescue and survival operations and in avionic systems technology and is a certified marine electronics technician and NARTE certified telecommunications technician. He has served in the U.S. Navy, Coast Guard, the Military Sealift Command-Pacific and has worked for Maersk Line Limited and Norwegian Cruise Line. Hareland currently works at China Lake Naval Air Warfare Station as a microwave-communications technician. He lives in Ridgecrest, Calif.

By Ocean Navigator