Thomson argues that conventional notions about grounding plates are ineffective and potentially dangerous. Routing lightning through the interior of a vessel to a plate near a mast step can force a charge to build up at the center of the boat and cause the side flashes that threaten the crew and electronic gear.
The National Fire Protection Association worked closely with Thomson to incorporate his principles in its 2008 standards for watercraft safety. NFPA recognized that his system is similar to lightning protection on a building, channeling the charge to ground along the exterior, rather than the interior, of a vessel.
Ewen Thomson and his ideas have proved troubling to the American Boat and Yacht Council (ABYC). It has balked at following the lead of the NFPA, some members of which have argued that ABYC’s long-standing lightning protection standard, which includes the centralized ground plate, should be eliminated from its catalog altogether. Instead, the ABYC in 2006 downgraded its lightning protection “standard” to a “technical paper,” intended to carry less weight among boatbuilders. At the same time, some of the language was modified to accommodate Thomson’s new ideas, but without specifically recommending or even explaining his Siedarc technology.
The ABYC’s lukewarm endorsement has not stopped a growing cadre of yacht designers from recommending Thomson’s system. Since the first installation, more than 30 vessels have received the Siedarc system, including a Great Harbour 37, a Nordhavn 55, a Nordhavn 62, the circumnavigating 60-foot power-cat Domino II and a 140-foot catamaran to be finished at the Pendennis Shipyard in the United Kingdom.
Thomson’s system is standard for Tags. “We put a lot of faith in Ewen’s research and designs and are happy to promote his work ...” Young says.
As this article was being written, that first Tag 60 was scheduled to sail from South Africa to the electric atmosphere of Florida.
Marine Lightning Protection Inc., 352-373-3485; www.marinelightning.com
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