Article by Capt. Steve Katz
Lightning
Chasing fish across the seas usually means your boat is docked in a warm weather climate with warm water temperatures. This good fishing climate is often the same weather that can create thunderstorms and associated lightning.
Traditionally it was the sailboat owners who were the most concerned about lightning strikes, and rightfully so, they do have a very tall mast, often made of metal or even conductive carbon fiber. Often you would see sportfish captains hoping there was a taller boat (possibly even a sailboat) near them in the marina that would be more attractive to lightning than their vessel. Many captains and owners quickly learned that is not just the tall boats that can be struck directly or indirectly by lightning, almost any vessel around a lightning strike can be affected. The NOAA weather service indicates that a typical lightning flash is about 300 million Volts and about 30,000 Amps. This electricity can travel through almost anything including air and water.
While we cannot control mother nature, we can prepare for a possible lightning event. There are companies that sell lightning prevention systems that could reduce vessel damage and personal injury by providing a path for the lightning or even deterring it to begin with. Some of these systems are engineered and tested systems based on industry guidelines, and some seem to be an attempt to push an unproven product.
What is a Lightning Protection System?
ABYC – The American Boat and Yacht Council offers Lightning Protection guidance as a technical report (TE-4) though it is not part of the standards that most boat builders adhere to when designing and building new boats. The National Fire Protection Association publishes Standard 780, “installation of Lightning Protection Systems” that is often also used as a guide to design lightning protection for watercraft. Most marine lightning protection system designs are based on engineering principles used in commercial and residential structures. This generally consists of an attractive metal at the highest point of the boat and wiring to direct the lightning charge downward through the vessel’s outer edges into the water. Installing a lightning protection system on a boat after it is built can be a time-consuming, labor-intensive task. When building a new boat, designing the lightning protection system alongside the other electrical and bonding system becomes an incremental cost during the construction process.
The basic components of a traditional lightning protection system include an air terminal at the highest point of the boat, connected to a primary conductor wire of #4 AWG or larger and secondary conductors #6 AWG or larger. These conductors should be vertical and straight as they head down to the water from the air terminal. Large metal objects such as tanks, engines, electric winches, etc., within six feet of any lightning conductor should be connected to the lightning protection system by means of a secondary lightning conductor. Due to electromagnetic induction, these lightning conductors should not be run alongside of other electrical wires since high frequency electricity (from lightning or other sources) can transfer from wire to wire without a physical connection.
When lightning enters a boat and does not have an easy direct path to the water, a side flash often occurs where the electricity travels on multiple paths through the boat on its way to the water. These side flashes are often the most destructive element of a lightning strike since they can travel along most any metallic object, mainly the boats wiring, engines, tanks, underwater gear etc. The side flashes bounce around the boat using the grounding and bonding system until the electricity exits into the water. Unfortunately, there are a lot of expensive items along the path from topside to bottom!
Direct or Indirect
Lightning does not need to make a direct strike on your boat to cause damage. A side flash, ground current, conduction, and streamers are an all components of indirect lightning that can cause damage to your boat. Boats in a marina share a common ground wire on the marina side of the shore power wiring effectively interconnecting the boats and can become a conduit for lightning related events. Additionally, the sensitive transducers and other devices connected to the underwater bonding system can also act as a path for the nearby lightning, including propellers and rudders.
What can I do to help decrease the damage of a lightning strike?
While there are many products designed to manage and direct a lightning strike by routing the electricity away from sensitive components, there are a few marine products that are designed to deter lightning from hitting your boat. Dinnteco and CMCE both offer lightning suppression and prevention systems for use on boats. Dinnteco defines the operation of their product “as a passive collector system of electrostatic currents that takes them to ground. The operating principle is based on balancing or compensate the variable electric field on the environment, avoiding the upward leader on the DDCE and on to the protected structure.”
Certainly, a lightning protection system can help mitigate damage in the event of a strike. In a perfect world, you could electrically disconnect all the boat’s vital electronics, navigation, entertainment, operational and propulsion hardware, though that is often impractical.
What to look for after a direct or indirect lightning event
Safety first! Check and test for electrical safety before boarding a boat after an event. Turn off the shore power and test the boat to be sure a compromised electrical system has not energized the grounding or bonding system which could cause a personal safety concern. A boat’s fiberglass or wood structure can be damaged, especially at or below the water line. Check for water leaks as soon as practical. Once the boat is deemed electrical and structurally safe by a professional, detective work can begin. After a lightning event, each piece of electrical and electronic gear needs to be checked for proper operation. Sounds simple though it is often difficult to detect a malfunctioning system. Many systems seem to operate initially but degrade or fail in the days or months following a lightning event.
Lightning is here to stay and unfortunately, we cannot prevent it, but we prepare for a situation of a direct or indirect strike using the above preventative measures. §
