The Cone of Protection

[Sue & Larry]

"Don't worry, we're within the cone of protection," we'd say to one another years ago while racing in our J-22. We really didn't know what we were talking about as we continued the downwind leg during the thunderstorm, but we felt better thinking there was some magical cone that would protect us from a lightning strike. Years later, I now know this theoretical cone is known technically as the "Faraday Cage." This "Faraday Cage", or cone of protection, is a concept that has comforted sailors for years. Although providing no guarantee, the cone of protection theory asserts that a well-grounded lightning rod or mast will provide a zone of safety about its base with a radius equal to the height of the mast. For a sailboat, this would create a secure zone over the entire boat under most circumstances. It's important to remember the "Faraday Cage," although widely accepted, is a theory not an absolute. Lightning can and does take parallel paths, jumps and strikes where it pleases, and still remains highly unpredictable as well as a heated topic of controversy, even among the experts. Crew members should minimize time on deck, and avoid bridging any metal objects (mast,stays,wheel,stove,radio,etc.) during a storm. Also, it's prudent to don rubber boots.