The Lightning Strike Totals Mac 25

Posted By: Casey Scurlock
Date: 7/28/99 2:57p.m.

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On July 20, 1998 my son Travis, then 19, and I were sailing at Lake Granby near the continental divide here in Colorado. We had been enjoying a beautiful summer sail when the wind switched around and began blowing in gusts from 20 to 30 mph. This is not and uncommon thing so I headed up the river to throw out a hook and eat some dinner. As we approached the anchorage, my son walked forward and paused by the mast for a moment. He grabbed the mast with his right hand and within 20 seconds the Windex was struck by lightning. Two guys on shore were waving and yelling at me! I had no idea what had happened or what they were saying. I later learned that they were asking if we were OK or if we needed a rescue! My son was OK, except for some tingling in his arm. We were an hour by water from help I couldn't hear and the electric's were fried. After a brief check of the bilge and one another, we headed back toward the boat launch. Two hours after the strike the first rain fell! We didn't notice any lightning for yet another hour. At no time did we notice any static build up. After many beverages and hours of discussion we assume that as soon as Travis touched the mast he interrupted the discharge of static that normally occurs. In effect, he became a sort of capacitor which momentarily stored a charge and changed the boat from being electrically neutral to either a +/- charge and made us attractive to the opposite in the clouds. The MacGregor 25 1985 model was not equipped with any type of grounding or static discharge systems. When it was struck by lightning, the lightning followed the mast and went through the mast step into the cabin. It vaporized the negative side of the electrical system, left a smoke trail on the battery, and blew out a "bunch" of 3/8 inch craters along the waterline. The mast and all the rigging was crystallized. The motor was not included in the estimate, but, we figured a complete rebuild. The new boat is a 1990 MacGregor 26 "Classic". The Anchorage, in Lyons Colorado, brokered the deal for the boat and made the modifications for the lightning protection system. We added a static dissipater brush to the mast (it must extend at least 6 inches above the tallest object attached to the mast.) It looks like a bottle brush and it provides hundreds of needle sharp points to bleed off any electrical charge into the atmosphere in microvoltage increments. We then ran a #4 copper cable from the mast step bolts in the cabin, down the compression post, through the liner, though a standard 6 inch hatch installed in the ballast tank, and fastened it to a copper alloy bolt in the 1 ft by 2 ft copper plate inset into the hull just to the starboard of the centerline. Since lightning like straight lines, we did not deviate over a couple inches over the 5 ft. length of the cable. The installation costs were reasonable and within my budget. This is my/our best guess at a lightning protection system. It is based upon current research from various Universities, including Univ. of Florida, and on various articles that have been published in the last 4 - 5 years. The system installed on my boat will, I hope, prevent me from being as attractive a target for lightning as I was. It will also provide a direct grounding path if I am struck again! I have been caught out in several severe storms since I started sailing "Tesla's Child" and I have never noticed any sign of static buildup. No clicking in the rigging or the mast. And I have never again been struck by lightning. I know that lightning can strike wherever it wants and that it is one of the reasons for the phrase "Act of God" in insurance policies. The next time that I pull the boat I'll take some photos of the hull and the rest of the installation.