"Did you ever get the feeling they have not perfected the science behind lightning
strikes yet?? (smile)."
On the contrary. The science behind electricity and lightning
strikes is extremely advanced. As an "airplane" person I am very familiar with the subject as relates to aviation. Commercial
airplanes are struck all the time - everyday! I am somewhat bemused(?) by the boating
community where there is a tremendous amount of pseudo science and old wives tales. Electricity is very predictable.
We just had a sinking 4 weeks ago here at our club. A J24 mast
was struck during a thunderstorm and the boat was holed and sunk on teh mooring
in 40 minutes.
After haulout I took a good look and it is clear the strike carried down the mast
and jumped off the mast below decks about 18 inches above the step. The strike went forward and blew out a 3 inch diameter hole about 5 inches forward of the mast. There were several smaller holes nearby suggesting that the strike separated upon leaving the mast.
The practice of tying all the metal bits together is called bonding. In aviation if you don't bond everything together the strike can jump across rudder
bearings effectively welding them in position.
So the basics of any plan require all the metal to be bonded together. Secondly the energy needs a path to ground. It will take the easiest path to ground so the path you provide has to be low resistance, hence large diameter wires and copper plates and so on.
I read that one argument for not bonding to the keel
is that a less resistant path may exist through the hull
of the boat rather than across corroded keel
boats. That's why the plate on the hull
is recommended because the water
is the closest path to ground and you are trying to make it also the least resistant.
The heat generated by a strike is important. This is why it is especially critical that filled keels and foam filled hulls not be used as grounding planes. The heat expands any moisture inside and we all know what happens when water
This is exactly what happend to the J24. Several of the smaller holes look like "explosion" holes. We surmise that captured moisture expanded and blew out. In fact event the main hole showed very little signs of arcing or burning.
I personally think the likelihood of a strike is tiny. But so is the likelihood of a sinking at sea and no one would consider a crossing without a lifeboat.
It's expensive but If I go across an ocean I will have a properly bonded boat with a low resistance path to ground.