Keith:
They say life is a series of trade-offs.
My current boat has a deck-stepped mast and inside ballast. If I do nothing
and get hit, I have lightning flashes either going through the hull and/or
melting the through hulls, not to mention bouncing around in the cabin
where, presumably, I am taking shelter.
(Stainless steel is a lousy conductor, so it's chancy to bet that any
grounding system using stays will offer lightning a good path to ground.)
The set-up I have is roughly based on what the experts recommend for smaller
powerboats, which have to install a temporary mast to make it work. I hope I
never have to find out just how good or bad it is.
If it melts the halyard but channels the strike into the water, away from
me, well, I figure the rain will put out the fire. (We get an inch an hour
in storms ...)
Jack Brennan
Shanachie, 1974 Bristol 30
Former C&C 25
Fort Lauderdale, Fl.
-----Original Message-----
From: Morgenstern, Keith E CIV SEA 08 NR
Sent: Thursday, August 30, 2012 9:29 AM
To: [email protected]
Subject: Re: Stus-List Isaac: Lightning on the hard
I think if your "lightning rod" rig ever did get hit, you'd find that
the heat from the bolt instantaneously melted the halyard to which it
was tied....
Which would result in the how rig dropping 50 feet to your deck. Not
sure how the deck would fair...
Add to that injury the insult that the stuff that was dropping (the
wood, the copper, the chain) was probably still on fire or certainly
glowing red. Which may set the deck on fire or at least scar it...
Unless it was a wire halyard. But the bolt may yet still melt the
nicropress that forms the eye in the halyard.....
Food for thought.
-Keith
-----Original Message-----
From: Jack Brennan [mailto:[email protected]]
Sent: Wednesday, August 29, 2012 16:56
To: [email protected]
Subject: Re: Stus-List Isaac: Lightning on the hard
I fashioned a home-made lightning rod for my boat.
I bought some thin copper tubing and strapped a four-foot section to a
piece
of hardwood, then attached 40 feet of no. 4 electrical cable to the
tubing.
To provide support for the cable, I ran 40 feet of line tied together at
set
intervals.
At the bottom of the cable, I used a ground strap to connect the cable
to a
length of chain, with the rest of the copper tubing wrapped around the
chain
to provide plenty of edge for the lightning to disperse. The line, of
course, is also tied to the chain.
The idea is to straighten the flexible tube at the top, then run it up a
spare halyard so the copper tubing is above the VHF antenna. Toss the
chain
overboard and you have a direct connection to ground without using your
rigging.
Of course, the best-laid plans ...
I had lightning strike very close a couple of months ago. But I was
anchoring in a cove at the time to wait out the storm and hadn't had
time
yet to deploy the lightning rod. A charge from the lightning zapped,
oddly,
my battery monitor and my 110-volt battery charger, both old pieces of
gear.
Everything else was fine.
-----Original Message-----
From: Martin DeYoung
Sent: Wednesday, August 29, 2012 4:40 PM
To: [email protected]
Subject: Re: Stus-List Isaac: Lightning on the hard
...but grounding it also makes it attract lightning. As there are
now
many grounded boats, It's now likely that the safe boats are the
ones
not grounded. <<
This statement differs from my understanding, granted I am no expert but
I
have read much on the topic and have sailed (mid-Pacific, Lake Ontario,
and
Puget Sound) with lightning striking the water within sight.
The theory I put the most stock in refers to the difference in potential
between the boat and the static charge (lightning's energy).
For example; if the ocean around your boat all has a plus 2 charge (++)
and
your mast has a plus 4 charge (++++) then the mast looks better than the
near by water. When underway and faced with a lightning storm I would
drag
jumper cables, chain, large gauge wire etc over the side with the other
end
attached to Calypso's rod rigging.
My expectation is connecting or bonding the sea to the mast would
equalize
the potential between them reducing the attractiveness of the mast to
the
lighting energy.
I am most interested in any experiences that support or refute this
strategy
in advance of my next lighting storm sail.
Martin
Calypso
1971 C&C 43
Seattle
-----Original Message-----
From: [email protected]
[mailto:[email protected]]
On Behalf Of [email protected]
Sent: Wednesday, August 29, 2012 1:27 PM
To: [email protected]
Subject: Stus-List Isaac: Lightning on the hard
Hi,
On Saturday, the weather predictions had Isaac a cat 2 hurricane heading
right for us. The travel lift at my marina was working over time, and
by
afternoon the boat yard ran out of stands and were only hauling out
those
who had their own stands. My boat remained at the slip, and I prepared
for
the storm. Fortunately for us, the path went more to the west, and we
experienced tropical storm winds and a 5-6 foot surge.
The only damage occurred to a sailboat which was hauled out. It was
struct
by lightning which blew out two transducers in the hull and burned a
line
along the hull from the keel forward to a chain which cross-connected
the
forward metal stands( due to the full keel, the chain actually touched
the
bottom of the hull). The keel was stepped on wooden blocks so it
appears
that the easiest electrical ground path was through the stands.
In short time, this incidence inspired many to ground their boats. One
guy,
actually has battery cables connecting his shrouds to a piece of rebar
pounded into the ground. I never though much about grounding (or
bonding) a
boat on the hard before, but I am not yet convinced that it is a good
thing.
Yes, if my boat is hit by lightning, I would want it well grounded, but
grounding it also makes it attract lightning. As there are now many
grounded boats, It's now likely that the safe boats are the ones not
grounded.
-
Paul E.
s/v Johanna Rose
Carrabelle, FL
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