On Mar 16, 12:52 pm, "Frogwatch" wrote:
On Mar 16, 9:58 am, dt wrote:



Don W wrote:

Roger Long wrote:

I'm not talking about doing it right here or protecting the boat. The
only aim is to increase the chances of remaining alive on a possibly
wrecked boat to deal with the aftermath. I'm just looking for a quick
stop gap to at least do something until I can put in a proper system.
It's tough on a boat with ballast encapsulated inside a fiberglass keel.

You've just figured out another important design criterion for a
sailboat--proper grounding for lightning protection. It needs to be
done as part of the design, instead of as an afterthought.

Regarding your aim of increasing your chances of remaining alive, I'm
not sure if you are talking about surviving the strike itself, or
possibly a sinking caused by the strike.

Don W.

Well, if he don't survive the strike, he probably won't survive the
sinking, either.

DT

A millisecond is a long time for lightning so the solder will probably
melt but will last long enough to conduct the pulse. The connection
is also crimped.
Many boats do get hit and survive and I'd go so far at to say that
most survive. You have to remember that at 10,000,000 volts, almost
everything looks like a conductor but some are better than others.
This means that a wet hull and deck look like perfectly good
conductors to the lightning. I have considered connecting the chain
plates together and then to the bolts at the mast step (deck stepped
mast) to try to make current that goes into the shrouds go back into
the grounded cable connected to the mast but this would make a huge
loop so am hesitant to do it.
I went so far as to use my dremel tool to round all edges on the chain
plates to suppress corona discharge from the edges.
You want to get that current to ground and do it with a large surface
area conductor which is why I use the many stranded wire. The
grounded plate has a lot of surface area too.
I think that the reason most struck boats survive is that the current
travels over the wet deck and hull surface which has huge surface
area. I have read that discharge pattersn are common on the outside
of struck boats , like Lichtenberg figures. My strategy is to
minimize this damage.


I believe that my battery cable will survive. Consider that lightning
rod cables survive multiple hits.

There is considerable disagreement over lightning protection
especially over whether you can prevent a strike by using pointy
conductors atop a structure. However, there is agreement on
protecting yourself when you are hit and that is to get the strike to
ground via a straight stranded cable.
I take an agnostic approach to the "pointy thing atop the mast
dissipating excess charge" and think that if it works that my Windex
will suffice.
BTW, if you have a carbon fiber mast and do not have a cable running
up the mast, you WILL lose the mast when struck. It has just enough
conductivity to conduct below the surface a bit and the heat in the
fibers destroys it.
A friend of mine in a 21' sailboat hit an overhead HT powerline. It
destroyed the mast leaving a very amazing melt pattern raining the
deck with molten Aluminum.
Another interesting thing is what happens to different trees that are
struck. Many trees survive being struck but not pines.