[Rhodes22-list] More INFO on Lightning/mitigation

Sat Jul 21 14:03:13 EDT 2012

Thanks Peter for getting all this info together.  I sent it on to my son and
his boat partners in Mexico sue to the fact that for the next 2 months there
are tremendous lightning storms very frequently.
Chris G

-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of peter klappert
Sent: Saturday, July 21, 2012 9:58 AM
To: The Rhodes 22 Email List
Subject: Re: [Rhodes22-list] More INFO on Lightning/mitigation

I was (am) of course grateful for the way Rhodies came thru with advice and
info about lightning. Hope no one took my silence otherwise.

I pasted your comments into a single document, as I often do with List
discussions. When I showed it to Ron, my marine electrician, he immediately
seized on one sentence in John Lock's helpful 2006 compilation:

"Lightning is a random and poorly understood phenomenon. Trying to avoid or
control it is probably futile and the results will be random and poorly
understood."

"That says it all," Ron said.

     >>>>o<<<<

Nonetheless, I've done a bit more research and want to pass on some of the
best links. I'll also paste in a short discussion from Practical sailor's
"Waypoints" blog.

http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf
     "Lightning and sailboats" This brochure from U FL helped a dummy like
me a great deal.

http://www.kp44.org/LightningProtection.php
      From the National Ag Safety Data Base

http://nasdonline.org/document/209/d000007/boating-lightning-protection.html
      "Lightning Protection on Sailboats"  From the official website of the
Peterson Cutter Owner's Group, this give you more links than you can shake a
lightning rod at.  

    >>>>o<<<<

The current issue of Seaworthy, the BoatUS online magazine, is devoted to
lightning--mainly to surviving it. Regarding prevention/mitigation, I found
these paragraphs were instructive:

1.  (You Can Run, But You Can't Hide) Volumes have been written about
methods to mitigate damage or even avert a lightning strike. Lightning,
however, doesn't seem to read them. As an example, one boat, fitted with a
popular "fuzzy" static dissipater at the top of the mast was struck twice in
one year; ironically, the second time the bolt hit the dissipater even
though the VHF antenna right next to it was higher. Dewey Ives, a surveyor
in Florida and member of the BoatU.S. Catastrophe Team who has seen his
share of lightning damaged boats, says that lightning is unpredictable.
"I've seen a small sailboat docked between two larger ones get hit and
sometimes a powerboat in the middle of a marina filled with sailboats gets
it. If lightning wants your boat, there's not much you can do about it."
Ewen Thomson agrees, "Current research shows promise in mitigating damage
from a lightning strike, but there is nothing that is effective in
preventing a strike." Though not everyone agrees with that statement, in
this issue of Seaworthy, we'll leave behind the sometimes contradictory
expert opinions on how to prevent a strike and focus on what to do if your
boat is hit. 

2. (Damage)  ...Though mast-mounted components are the most likely to be
destroyed, anything on the boat that is electronic can be damaged. In the
case of Priority, the wind, speed and depth instruments were destroyed as
was the air conditioner controls, the battery charger, autopilot, mast
wiring, the refrigeration controls, the stereo, and of course, the VHF. In
other cases, battery selector switches, power panel breakers, volt/amp
meters, alternators, and even cabin lights were damaged. As a general rule,
if the equipment works OK after the boat was struck, it probably wasn't
damaged-it's unusual for electronics to fail months later. Dewey Ives says
that often the first sign owners have that their boat was struck is that
some of the boat's electronics don't work. "Look for fuse failures," he
says. "If you have more than a couple of blown fuses, look to lightning as a
possible cause." Power boats, he says, though not struck as frequently, are
just as likely to sustain electronic damage.
     Occasionally, lightning may take a path to the water directly through
the hull. When it does, it can blow a hole through the fiberglass. The good
news is that the damage is repairable. More good news: Most strikes don't
cause this type of damage...

3. (Hull Damage) ...As hard as lightning is on electronics, it can be just
as brutal to fiberglass. In the case of Priority, the lightning traveled
down the mast as well as through the VHF coaxial cable. The cable had been
disconnected and was resting against the hull inside the boat. When the
strike exited the cable, it had no easy way to get to the water. After
traveling a quarter of a mile through air, lightning has no trouble going
through a fiberglass hull, and this is exactly what it did, blowing a
three-inch hole on the way. Fortunately, the hole was above the waterline
and the boat was saved from sinking. (Note: If you disconnect your VHF cable
from your radio during lightning season, like some boaters do, be aware that
anything near the connector, including you, can get zapped during a
strike.)...
     Giving the lightning a low-resistance path to the water is a good idea,
but if it's not done right, the damage can be even worse.  

     >>>>o<<<<

Here's the short article from PS:

Getting the Charge out of Lightning

Most boat owners have only the vaguest idea of what is involved in
protecting their boats from lightning damage. Many believe that their boats
are already protected by the boat's grounding system. Most are wrong.

Just because your boat may be bonded with heavy copper conductors connecting
the masses of metal in the boat doesn't mean that it is protected against
lightning. A bonding system may be a part of a lightning protection system,
but bonding itself offers no protection to the boat unless a good, direct
path to ground is part of the system.

While neither aluminum nor stainless steel is an outstanding electrical
conductor, the large cross-sectional area of both the mast and the rigging
provide adequate conductivity for lightning protection. The trick, however,
is getting the electricity from the mast and rigging to the water.

The straighter the path is from the conductor (mast and rigging) to ground,
the less likely are potentially dangerous side flashes. Put simply, side
flashes are miniature lightning bolts which leap from the surface of the
conductor to adjacent metal masses due to the difference in electrical
potential between the charged conductor and the near by mass of metal.
Ideally, therefore, the path from the bottom of the mast and rigging to
ground would be absolutely vertical. In practice, this is rarely achieved.

If the boat has an external metal keel, the mast and standing rigging is
frequently grounded to a keelbolt. There are pitfalls to this method. First,
the connection between the bottom of the mast and rigging to the keelbolt
must be highly conductive. ABYC (American Boat and Yacht Council) standard
TE-4 for lightning protection systems require that these secondary
conductors have a conductivity at least equal to that of AWG #6
copper-strand cable. There is no drawback to using an even larger conductor.

Connecting the short conductor to the mast and keelbolt presents some
problems. A crimp eye can be used on the end that is to be attached to the
mast, but you may have to fabricate a larger eye for attachment to the
keelbolt. This can be made from sheet copper. Soldering the connections is
not recommended, since the heat generated in a lightning strike could melt
the solder.

Then you have to face up to a basic problem. Your mast is aluminum, yet
you're connecting it to ground with a copper cable. Everyone knows that
aluminum and copper are not galvanically compatible, so what's the solution?
While it will not eliminate corrosion, a stainless steel washer placed
between the copper cable's end fitting and the aluminum mast will at least
retard it. But this connection is going to require yearly examination to
make sure that a hole isn't being eaten through the mast. In addition, of
course, the process of corrosion creates wonderful aluminum oxide
byproducts, which have very low conductivity. The aluminum oxide may reduce
conductivity to the point where your theoretical attachment to ground is in
fact non-existent. Once again, disassembling the connection and cleaning it
yearly are essential to maintain conductivity. Constant attention to all the
conductor connections is essential in any grounding system, whether it's for
lightning protection or grounding of the electrical system.

For more information on how to best protect your boat from lightning
strikes, purchase Nigel Calder's " Boatowner's Mechanical & Electrical
Manual," from Practical Sailor.

----- Original Message -----
From: "Chris Geankoplis" <napoli68 at charter.net>
To: "The Rhodes 22 Email List" <rhodes22-list at rhodes22.org>
Sent: Saturday, July 14, 2012 6:15:54 PM
Subject: Re: [Rhodes22-list] Lightning mitigation

Grounding a mast does not protect it from being hit, in fact there is a lot
of evidence that there is a slight increase in incidents.  I think that the
idea is that the flow of electrons can dissipate rather than build up, but
the difference in potential when talking about hundreds of thousands of
volts is very little.  The advantage for a grounded mast is when you are
struck you will direct the path of the electrons and its exit point.  A word
of caution, grounding to a single bronze through hull can have disastrous
results as the fitting can heat almost to incandescence and any water
trapped nearby is vaporized.  I have seen a through hull blown out of a
boat, not good.  You will need something that has several square feet of
surface area such as a copper plate.  Often when an ungrounded mast is hit
the lightning travels to the base of the mast (if deck stepped) and then
jumps to the water line right through the hull.  This can burn a hole in the
fiberglass, but what do we care our boats are unsinkable.

Chris G

-----Original Message-----
From: rhodes22-list-bounces at rhodes22.org
[mailto:rhodes22-list-bounces at rhodes22.org] On Behalf Of Goodness
Sent: Saturday, July 14, 2012 6:59 AM
To: The Rhodes 22 Email List
Subject: Re: [Rhodes22-list] Lightning mitigation

If your boat mast is grounded then a lightning strike to the mast is not
really going to happen.  Many carry jumper cables and when a storm comes up
clamps to a mast fitting and toss the other end overboard.  A more clever
solution is an internal grounding wire to a metal underwater through
hull......however that through hull needs to be protected with a zinc or it
will corrode big time and sink you.  I have seen lightning switches that you
flip in a storm too.  On a dock on a lift, it would be smart to ground the
mast to the actual ground, very little corrosion risk there.

On Jul 14, 2012, at 12:51 AM, peter klappert <peterklappert at comcast.net>
wrote:

> 
> Just to bring you all up to date and ask a question (or two).
> 
> Did I mention that the day I discovered the damage the Tampa Bay Times
reported that Tampa has lost its (completely unofficial) status as lightning
capital of the world?
> 
> I may as well get to the important question right away, then rattle on for
anyone interested in the patient's health. So here's the question: 
> 
> What kind of lightning mitigation does the R22 have? For example, it might
be heavy guage wire or cable connecting the shrouds to centerboard or some
other metal below the waterline.
> 
> Does anyone know? Or has anyone done or modified this sort of thing on
their boat?
> 
> Here's the latest news. If I had more time I could make this shorter, but
it's past midnight and the marine electrician is due at 8 A.M.
> 
> The damage to Aeolia is, of course, more extensive than I knew when I sent
the list under the subject "Major Electrical Problems." But it's not much
more extensive, just quirky and seemingly patternless.
> 
> There is no visible damage to hull cabin or rigging, but most electronics
are fried, as are running and anchor lights; the VHF aerial apparently got
melted out of its mast-top mounting. So far wiring seems to be ok, with some
fuses blown and some not. The outboard's electric starter is gone, but the
motor starts manually and runs like a purring cat. Both main & Genoa look to
be like new--I was concerned because of their proximity to metal. 
> 
> I'll know a lot more after this weekend and hope to have Aeolia out on
Tampa Bay sometime next week.
> 
> The concensus among those I've talked to is that having the boat elevated
on the lift and the aluminun lift itself increased likelihood of my boat
being either struck or damaged by a strike nearby. Still, the total height
of Aeolia on the lift, including 2-foot VHF aerial, is only about 36-37 feet
above mean high tide. 
> 
> One leg of dock wiring is shorted, but that may be unrelated. Aeolia was
not on shorepower at the time and the hull made no direct contact with
metal--it was on the carpet-covered PT lumber of the lift bunks. Odds are
that was part of the problem.
> 
> Obviously I need to make sure the lift is grounded (never thot to wonder
or doubt it until this happened) and the guy who built the dock is looking
into what might be possible and legal by way of a lightning rod on a pole.
His power boat has a 24' metal antenna and has never been struck. My next
door neighbor docked his C & C 34 behind his house for many years without
incident. Lightning strikes--or damage, at least--among the big sailboats on
the other size of Apollo Beach (in Bal Harbor) are reputed to be rare.
> 
> G'night!
> 
> 
> 
> 
> 
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