The other reason is that, with a metal boat, any path through the boat to the sea is a valid one. A boat without low-resistance paths to ground could support a relatively strong induced positive charge up high, which the step leader could feel from farther away. Most points on a metal boat are at essentially the same potential (voltage) as the sea surface the step leader can’t really feel the boat unless it gets within 20 m or so. You can think of the step leader as “sniffing out”, in each step, the most strongly positive electric field within about twenty metres of its current point (this is the origin of the very useful “beach ball” geometry Erik mentioned). One is that almost everything on board is conductive and electrically connected it’s therefore very difficult for voltage differences to build up. I would say there are two big advantages, if you’re in a lightning storm, to having a metal boat. As I understand it from your post, this should make us more likely to get hit (although less likely to suffer damage) but once again we have been in at least one truly spectacular lightning storm off Florida with strikes all around us, but no hits.ĭo you think we have just been lucky, or do you think that there may be some validity to my metal boat protection theory? Since then we have had a lighting rod connected to the hull with #4 cable just as you recommend above. What makes it even more interesting is that up until eight years ago, when we replaced our aging and cracked aluminium mast with one made of Carbon, we had no terminals at all. (I have also talked to other metal boat owners who have experienced the same thing.) My theory has always been that because our boat is metal and therefore an extremely good ground plate, that we were discharging the air above the boat and therefore creating a “zone of protection” around us. In each of these cases MC’s mast was clearly the highest thing around, and yet we escaped unscathed. In one case, so close that I saw steam rise from the water at the strike location. One question: Over the years I have seen lightning strike several times into the water very close to “Morgan’s Cloud”. A great post that explained a lot of stuff about lightning that I was not clear on.
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