Had to do some "studying" of lightning protection for some work at a facility that destroyed chemical weapons out in Colorado. There is an NFPA standard for lightning protection that may not be exactly applicable for a sailboat but the key principles seem to apply. Simplified, they are:
1. There will be a "cone of protection" that looks kind of like a christmas tree provided by lightning protection if you can get the strike directly to the ground. It would seem that the safest place during a lightning strike on a sailboat would be in the cockpit where you are protected by the "cone of protection" rather than inside the cabin where the strike might "jump" to try to get to ground (see items 2 and 3 below).
2. Lightning will take the easiest path to ground and that current may "split" and "jump" from the primary ground conductor to wherever it needs to jump to to get to ground. During that "jump" it will create a "spark" like a spark plug and for a boat, that jump might just blow a hole in the hull if it jumps to something like a thru hull or chain plate.
3. Lightning doesn't like to make "sharp turns" along its path to ground and may just escape the grounding wire and jump to something else to get to ground. There is a minimum radius for any "ground wire turn" in design of lightning protection systems. I would hazard to guess that many of our boats with ground wires from the mast to the keel probably violate that minimum radius.
catalog.nfpa.org
1. There will be a "cone of protection" that looks kind of like a christmas tree provided by lightning protection if you can get the strike directly to the ground. It would seem that the safest place during a lightning strike on a sailboat would be in the cockpit where you are protected by the "cone of protection" rather than inside the cabin where the strike might "jump" to try to get to ground (see items 2 and 3 below).
2. Lightning will take the easiest path to ground and that current may "split" and "jump" from the primary ground conductor to wherever it needs to jump to to get to ground. During that "jump" it will create a "spark" like a spark plug and for a boat, that jump might just blow a hole in the hull if it jumps to something like a thru hull or chain plate.
3. Lightning doesn't like to make "sharp turns" along its path to ground and may just escape the grounding wire and jump to something else to get to ground. There is a minimum radius for any "ground wire turn" in design of lightning protection systems. I would hazard to guess that many of our boats with ground wires from the mast to the keel probably violate that minimum radius.
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