Larry wrote:

http://www.thomson.ece.ufl.edu/lightning/

This sailor has done extensive research at ufl.....

Thanks, that was one of the first things I turned up. This quote is
especially applicable to this thread in view of Wilbur's comment that an
ungrounded boat is less likely to be struck:

"While the individual estimates varied widely between surveyors, there is no
support for the argument presented by some sailors that they should not
ground 'their sailboat since it will increase the chances of it being
struck by lightning."

The statistics presented in this article make a good case for just
forgetting about it unless I plan to sail south, which I do hope to do at
some point.

My original post was actually prompted by this and a couple of other web
articles. Here is my situation:

http://home.maine.rr.com/rlma/Keel.jpg

The mast stanchion is essentially equal to a keel stepped mast. Since my
boat was originally a keel / centerboarder, the keel is large volume and I
doubt that Endeavour spent the money for a keel casting. I'm quite sure the
ballast is just stacked lead pigs in resin. Lighting current going through
that stuff would be like a bomb and the high resistance at the bottom of the
main conductor would create extensive side flashing.

For reasons not evident on the crude drawing, any grounding plates have to
be outboard of the cabin sole. The Thomson paper says not to let grounding
conductors contact the hull but I have no choice if I am to maintain the
maximum radius recommended by other sources. The reason for overkill on
conductor and ground plate size is to compensate for the tight conductor
radius and need to run the conductors close to the hull skin.

--
Roger Long




















--
Roger Long