On Thu, 15 Mar 2007 23:22:43 -0500, Don W
wrote:

Roger Long wrote:

Like the vast majority of fiberglass boat owners, I'm sailing around in a
boat with next to no lightning protection. I have run a heavy copper
grounding wire from a chain plate to a couple of through hulls directly
below. That will help bleed off some charge and slightly reduce the chance
of being struck. If I am hit however, I imagine it will make the results
worse.

This is on my "someday" list and would be on the "already done" list if I
sailed more to the south. I nearly 40 years of sailing in this part of the
world, I've only once been in a situation that I was huddled below trying to
figure out the best place to be when the bolt hit. That was long ago enough
that I haven't gotten as worked up about the issues as I should.

I don't know as much about the subject as I should since I've spent my
professional life working with boats that have metal masts welded on top of
metal superstructures welded to metal hulls. So, I throw out this idea for
comment as a suggestion for either an interim solution or for cruising
grounds where energetic storms are too infrequent to justify a major
retrofit.

How about a couple of plastic coated battery cables with a snap shackle on
one end and a length of chain on the other. If it looks like you are going
to get caught right in the path of an energetic storm, the kind where you'll
want to either anchor or drift while you seek the safest place in the boat,
just clip them to the shrouds and drop over the side. Nearly straight run
down from the stays (at least if chain plates are not too far inboard), lots
of surface area in the chain, plastic coated wire to protect the topsides.
You wouldn't want to cruise around with this rig but it seems like it might
at least keep a strike from sinking the boat by blowing a hole in it.

--

Roger Long

Roger,

If lightning hits your mast, your battery cables
and chains are not going to help much, although
they probably won't hurt either. I've got the
electrical engineering degree with a bunch of
experience to back it up, but lightning protection
is a specialized black art--even in my field.

There are some pretty good explanations on the web
by PHd's who have made lightning protection their
whole career. Search them out and give them a
read. It's an interesting subject.

Good luck,

Don W -- who is still scratching his head about
what to do about lightning protection for his
Irwin 38.

FWIW,
I took a hit from lightning whilast at anchor in Langkawi, Malaysia.
My 42 footer is strip planked and sheathed with GRP.
The path of the lightning which melted the VHF atnenna and tricolour
at the masthead was down the twin backstays. Both the large ceramic
insulators on the one used as an aerial blew to pieces. Later, we
recorded a smell of antifouling. It appears that one backstay (not the
aerial one) internal chainplate bolt was touching a large tin of
antifouling as well as one of the bolts for the drop down ss ladder
which was in the water. A small hole was blown in the side of the can.

Every connected electronic item and all instruments were blown. The
computers were fine.

Now I am deminically paranoid about lightning. I race around and pull
out all plugs, wires, aerials and power cables. It was a real pain
with the 13 to the Raytheon autopilot but I fed all to a single plug
which goes back like a breeze. Yes, I've heard of electromagnetic
induction. I throw everything that fits into my stainless oven.

It feels good to be sailing along with just the compass but have
learned to take note of the heading first.

Did secure a large cable and chain to one capshroud but the bumping
along the hull was too annoying. I like the idea of traing one from a
backstay however.

Seem to recall hearing somewhere that chain is not good as a
conductor. - any ideas please. It is rather scary being the tallest
thing for miles of ocean when you see lightning ahead. This thread is
of intense interest.

cheers
Peter Hendra