[alberg30] Lightening Protection

Bill,

I did a bunch of research a number of years ago.  I don't 
remember all the details, but there are no easy answers.
Lightning is very unpredictable stuff and not amenable to
repeatable testing.  I've meant, for years, to organize
and summarize that information but I've never gotten a
round tuit.  Much of the popular literature makes no
distinction between actual lightning strikes and smaller
secondary discharges.

I do know that, if you ground your mast or an air terminal,
you need to do a good job of it or you're likely to make
things worse.  Lightning doesn't like to make turns, so
a relative straight path is essential.  

Also essential is an effective and sturdy grounding plate.  I've
heard of boats using bronze through-hulls for grounding and a
lightning strike blew them out of the hull, sinking the boat.
You need at least one square foot of copper, and preferably
two.  This grounding plate needs to be able to pass a large
current; Dynaplates won't do this.

If I had a keel-stepped mast and an exposed lead keel, I'd
be inclined to run a grounding conductor down the mast to the 
keelbolts, and perhaps also to a copper grounding plate.
With a deck-stepped mast and encapsulated ballast, I've
elected not to ground.  Fortunately, outside of Florida,
lightning strikes of boats are relatively infrequent.

 - George


> Bill Newman said:
> 
> Does anyone have any informed comments on this, installed it,
> how, any experience with a strike?  I have heard that grounding may make
> the boat a more likely strike target.


-- 
 ----------------------------------------------------------------------
  George Dinwiddie                                  gdinwiddie at min.net
  The gods do not deduct from man's allotted span those hours spent in
  sailing.          http://ourworld.compuserve.com/homepages/Alberg30/
 ----------------------------------------------------------------------