[Rhodes22-list] Reposted on Lightning (reply of 7/30 1:12pm)

[Hank]

Of course, all of you golfers out there know the really best way to prevent
a lighting strike is to just hold up your 1 iron because not even God can
hit a 1 iron!

Hank

On 8/2/06, TN Rhodey <tnrhodey at hotmail.com> wrote:
>
> Art,
>
> Thanks for re-posting. I agree with his comment about protecting small
> sailboats..... " lightning protection on these boats also should be
> regarded
> as a last resort, with storm avoidance being the best defense".
>
> Wally
>
>
> >From: "Arthur H. Czerwonky" <czerwonky at earthlink.net>
> >Reply-To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
> >To: rhodes22-list at rhodes22.org
> >Subject: [Rhodes22-list] Reposted on Lightning (reply of 7/30 1:12pm)
> >Date: Wed, 2 Aug 2006 05:33:46 -0400 (EDT)
> >
> >All,
> >I am reposting this reply from Ewan FYI.  I was told the first copy was
> >quite garbled.
> >Art
> >
> >
> >Dear Art,
> >
> >Thank you for forwarding this lively and interesting discussion.  Since
> it
> >contains so many points of view,  it is impracticable for me to address
> all
> >of them.  For example, of the four "INTERESTING FACTS" mentioned
> below,  I
> >would agree with just one of them -
> >Being caught out in a sailboat during a lightning storm does not mean you
> >are going to be struck.
> >However, even this one comes with a  disclaimer.  Compared with being in
> a
> >marina close to other boat masts, being caught out in a thunderstorm
> >increases your probability of being struck by perhaps a factor of five or
> >ten.   The empirical evidence for this estimate is Boat US insurance
> >statistics.  Specifically, lightning damage to catamarans is twice that
> to
> >monohulls. The brief explanation for this is that catamarans are wider
> and
> >so there is less protective effect from neighboring masts in marinas.
> >
> >My best attempt at addressing the relevant issues are  contained in my
> web
> >pages at www.marinelightning.com , that have been updated very recently.
> >But even here I realize that there is so much information scattered over
> >so many pages that it is difficult for the lay sailor to come to grips
> with
> >the most important concepts, and why should anyone believe what I have to
> >say, as opposed to, for example, the bristle brush salesmen who have a
> much
> >cheaper product that, if you believe them, may actually prevent lightning
> >from striking  in the first place?   (For one answer to this see
> >http://www.marinelightning.com/AirTerminals.htm .  For another, Boat US
> >have a photo of a seriously listing catamaran whose bristle brush is
> still
> >intact at mast head following a lightning strike.  )
> >
> >Here is an overview:
> >
> >The home page www.marinelightning.com summarizes our approach, as
> having  a
> >foundation in peer-reviewed science,  being consistent with observations
> of
> >actual damage, and  being considered by the lightning protection
> committee
> >of the National Fire Protection Association for inclusion in the 2007
> >version of NFPA 780 (see pages 21-28 in
> >http://www.nfpa.org/Assets/Files/PDF/ROP/780-08-ROP.pdf   ).
> >
> >Perhaps the most straightforward explanation is that on
> >http://www.marinelightning.com/science.htm .  After a brief historical
> >introduction, the relevant lightning discharge processes are described
> and
> >reasonable solutions are proposed.  A key point here is that we attempt
> to
> >build a marine lightning protection system that simulates that on a
> >building - with multiple air terminals, down conductors on the outside,
> and
> >multiple grounding terminals around the perimeter.  Note that this is a
> >very different scheme than the commonly used one of a single cable
> through
> >the middle of the boat that terminates in a single one-square-foot ground
> >plate, which is a good way to maximize the risk of sideflashes.
> >
> >Products that have been developed to a commercial stage are described on
> >http://www.marinelightning.com/products.htm These include the Siedarc
> (TM)
> >grounding electrode, the GStrip (TM) 1 square foot grounding strip, and
> the
> >ZzapStrap (TM) bonding strap for a boat on a boat lift.   The prices on
> all
> >products are less than or comparable to those on similar products
> available
> >elsewhere.  For example, a Siedarc (TM) electrode with  4' of cable is
> $215
> >compared with $419 for the single-electrode Strikeshield model CSSB-15.
> >The CSSB does come with a mast-mount connector, but otherwise the two are
> >very similar.   Internal connections for the Siedarc can be made with
> >inexpensive heavy duty lugs.
> >
> >As you can  tell from the above, the installation of a reasonably
> effective
> >lightning protection system is not trivial, and every boat is a custom
> job.
> >  However, there are huge cost/benefits  for a one design such as the
> >Rhodes 22  if the manufacturer is motivated to add this feature during
> >production.  A complete system should be possible for a few percent of
> the
> >cost of a new boat.  This is where your discussion group may be able to
> >make a difference.  If you could convince General Boats ( 252-482-4372)
> >that you, the customer, would like to see this feature on your boat then
> >something is likely to happen.  Once a system and components have been
> >designed for new builds, retrofits should be possible at an affordable
> >price.
> >
> >I would really like to help.  Since I have a commercial interest in this,
> >it is inappropriate for me to post anything directly on your message
> board.
> >  However, please feel free to quote me in any way that you feel is
> >appropriate, and let me know if there is  anything else I can do to .
> >
> >Best regards,
> >Ewen Thomson.
> >
> >Arthur H. Czerwonky wrote:
> >
> >Dr. Thompson,
> >
> >We have a discussion in progress on lightning, and how skippers of the
> >Rhodes 22 fleet could best provide protection for crew, boat, and
> >electronics in the event of a lightning accompanied storm underway.  The
> >below 'wisdom' is a poor substitute for your studied insights for sure,
> but
> >does this approach hold any promise for effectiveness?  The '35 foot
> >conductor from mast head to the copper plate' would probably have to be 4
> >gauge.  Does this solution make sense?
> >
> >Would appreciate your suggestions.
> >This reminds me of the first lightning protection system for my Mirage
> 5.5.
> >  The maiden cruise in July 1986 was to Cumberland Island, GA, in the
> depth
> >of a thundery summer. The new boat had not come with lightning protection
> >since the builder assured me "we don't add that because it just attracts
> >lightning".     So I cobbled together  a temporary system consisting of
> two
> >fairly large aluminum plates attached to copper braid.  The theory was
> that
> >one end of the braid would be wrapped around the mast and the two plates
> >thrown over each side just before a thunderstorm.  Remember this was
> 1986,
> >long before I realized that tinned copper braid is likely to corrode any
> >aluminum it comes in contact with, and is likely to self destruct during
> a
> >lightning strike.  In any event, and, with 20/20 hindsight, completely
> >predictably, the plates never did get deployed.  When the inevitable
> storm
> >rolled in we were nowhere near the boat, which was maybe just as
> well.  We
> >were onshore at Cumberland Island holed up in the visitor's center
> watching
> >the unprotected boat swing wildly at anchor as a lightning strike nailed
> >one of our close neighbors.  Lesson learned:  Don't rely on a temporary
> >system.  Soon after that my Mirage had what was, at that time, a
> >state-of-the art system consisting of an aluminum rub rail along the
> >centerline that was connected to bow pulpit, chainplates, iron keel, and
> >aluminum rub rail.  See
> http://www.thomson.ece.ufl.edu/lightning/video.html
> >for a video tour.  This system is now due for an upgrade.  Even though
> the
> >boat spends the majority of its life on a trailer, the aluminum rub rail
> is
> >corroding.  Besides, it is in the middle of the boat rather than near the
> >waterline and so is scheduled to be pulled off and replaced by six
> >electrodes just above the waterline.  Also, the connections were not up
> to
> >par and will be beefed up to be at least as good as #4 gauge copper wire.
> >The design constraints are tight given the limited interior space of the
> >Mirage 5.5, and the main problem is not how to do it, but how to do it
> most
> >simply, with the least cost, and acceptable aesthetics.
> >
> >There are a couple of interesting  postscripts to the 1986
> >discussion/argument concerning lightning protection.  The question as to
> >whether the act of grounding a mast increases the risk of a lightning
> >strike was a valid one.  While a scientific explanation based on
> >electrostatic theory  predicted that bridging the short gap between mast
> >base and water should have an insignificant effect on the electric field
> at
> >mast head, that is, an answer in the negative, it would be nice to get
> some
> >empirical answers. So Sea Grant funded a two-year research program in
> part
> >to get an answer.  The results  are published in a Sea Grant bulletin
> >(SGEB17 - see http://www.thomson.ece.ufl.edu/lightning/SGEB17.html or
> >http://nsgl.gso.uri.edu/flsgp/flsgpg92001.pdf ) and presented in a video
> (
> >http://www.thomson.ece.ufl.edu/lightning/video.html )  The answer to the
> >strike probability question is given  at
> >http://www.thomson.ece.ufl.edu/lightning/SGEB17.html#Attachment   In
> >another development, the builder,  Ken Fickett of Mirage Manufacturing,
> >has since become a staunch advocate of  lightning protection and close
> >collaborator.  We are just completing the first installation of a
> complete
> >system on a  Great Harbor 47 which we plan to write up for publication in
> >PassageMaker.
> >
> >
> >R,
> >
> >Art Czerwonky
> >
> >-----Forwarded Message-----
> >
> >From: "Arthur H. Czerwonky" <czerwonky at earthlink.net>
> >Sent: Jul 29, 2006 6:31 PM
> >To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
> >Subject: Re: [Rhodes22-list] sailing and lightning (long reply)
> >
> >John,
> >
> >Helpful insights on a nebulous potential problem.  This could be a
> logical
> >approach - about 35' of insulated heavy gauge cable run up the mast on
> the
> >main halyard connected so as to project the top end about 12" above the
> >masthead, connected to the other end with a copper plate welded/soldered
> >and crimped, which would be put into the water near one of the upper side
> >stays.  The top end would best have a 'spear' type end attached.  It
> would
> >be used when strike probability is high, otherwise stowed forward.
> >Thoughts?
> >
> >Art
> >
> >
> >
> >-----Original Message-----
> >
> >From: John Lock <jlock at relevantarts.com>
> >Sent: Jul 29, 2006 3:12 PM
> >To: The Rhodes 22 mail list <rhodes22-list at rhodes22.org>
> >Subject: Re: [Rhodes22-list] sailing and lightning (long reply)
> >
> >At 03:31 PM 7/28/2006 -0700, Tootle wrote:
> >
> >http://www.cdc.gov/nasd/docs/d000001-d000100/d000007/d000007.html
> >
> >And since John Lock would rather read than sail, maybe he should
> reasearch
> >this one.
> >
> >That is an incorrect statement.  I would rather be sailing!  But
> >since I am nowhere near water and don't have a boat, well...
> >
> >I already did some research on the subject because it concerned me
> >when the sailing bug first bit (not long ago).  Here are some salient
> >facts and observations that I have found valuable - YMMV.
> >
> >First, there are two schools of thought on adding lightning
> >protection to your boat:
> >
> >1) 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.
> >
> >2) Doing something is better than doing nothing and maybe it will
> >help.  Besides it's a cool project.
> >
> >I suspect that both points of view have merit and which one you
> >subscribe to probably says more about your personality than your
> >technical skills ;-)
> >
> >SOME INTERESTING FACTS _
> >
> >* Boats in saltwater are more likely to be struck than boats in
> >freshwater, due to saltwater's higher conductivity.  However, boats
> >struck on freshwater are more likely to be severely damaged due to
> >the higher current loads in the strike itself.  (All this being
> >relative to the small likelihood of getting hit in the first place.)
> >
> >* Powerboats are potentially more dangerous in a storm than
> >sailboats, because their lower profile means a greater amount of
> >current is needed to make a strike.  So, if you're out in a typical
> >fiberglass runabout and get struck, poooof.
> >
> >* Being caught out in a sailboat during a lightning storm does not
> >mean you are going to be struck.  There are many accounts of people
> >witnessing water strikes very near their boats.  Many other factors
> >are involved in setting up a lightning strike.
> >
> >* Boats with lightning protection systems "may" be more likely to be
> >struck, but experience less damage.  There only seems to be anecdotal
> >evidence of this, but the theory seems sound.  That is - if you give
> >lightning somewhere to go, it may hit you first, but be dissipated
> >more readily (see more on this further down).
> >
> >SOME MYTHS TO BE DEBUNKED -
> >
> >"Mooring your boat among boats with taller masts will protect you"
> >
> >Lightning is seeking it's best path to ground.  Height (or the
> >distance of the "air gap") is only one factor.  Other factors - such
> >as mast/keel composition, deck or keel stepped masts, presence of
> >other grounding objects near the waterline, etc - will ultimately
> >decide the lightning path.  For example, a lead-keeled, keel-stepped
> >boat may be more likely to be struck than a deck-stepped, centerboard
> >boat with a taller mast.  And you can't survey all those boats you've
> >parked amongst, so it's false security.
> >
> >"Clamping jumper cables on a shroud and dangling the other end in the
> >water is good enough"
> >
> >While that sounds good on the surface, it is in fact a very bad
> >idea.  The problem is that you are depending on relatively small
> >surface areas to conduct a helluva lot of current.  The connection
> >points between the shroud and the mast and the jumper cable clamp and
> >the shroud are not sufficient to conduct the amount of current a
> >strike produces.  However, you have increased the likelihood of a
> >strike by providing a grounding path.  I would strongly discourage
> >this practice. (There is also a similar method, which involves
> >wrapping the anchor chain around the mast.  Same problem.)
> >
> >"Adding a good lightning protection system will protect me and my boat"
> >
> >Well, maybe...  There is at least one documented case of a
> >well-protected boat being sunk by a strike.  The mast and all the
> >shrouds were grounded via heavy copper cable to a copper plate
> >epoxied onto the bottom of the hull.  However, there was some
> >moisture behind the plate.  When the strike occurred, that moisture
> >was instantly vaporized into steam and exploded the plate off the
> >hull (with obvious results).
> >
> >SOME GOOD IDEAS IF YOU PLAN TO ADD A LIGHTNING SYSTEM -
> >
> >* Use nothing but heavy-gauge (#4 or larger) copper conductors.  All
> >other materials will corrode or provide inferior conductivity.
> >
> >* Keep all leads as straight as possible.  Any sharp bends or kinks
> >will defeat the purpose.
> >
> >* Provide lots of contact surface.  Snaps, hooks, turnbuckles, etc.
> >will not conduct the current loads you get in a typical strike.  Use
> >large connecting plates, bolts, and flat washers, clean connecting
> >surfaces and seal from weather.
> >
> >* If you have a system installed, don't do anything to defeat it if
> >you're caught in a storm.  For example - don't hold onto the backstay
> >while you pull up the swim ladder or fiddle with the outboard.  You
> >may involuntarily become an integral part of the lightning system (as
> >Bill E. so eloquently described :-) )
> >
> >VARIOUS LIGHTNING PROTECTION SYSTEMS -
> >
> >There are basically three commercially available systems in use at
> >varying costs and perceived effectiveness.  Again, this assumes that
> >you subscribe to the "something is better than nothing" school of thought
> -
> >
> >1) Complete grounding systems - the mast, shrouds, motor, electronics
> >and any other conductive materials are wired into one or more
> >grounding leads, which go thru the hull to a flat copper plate
> >affixed to the exterior.  Yep, that means you have to drill one or
> >more holes to bring the conductor thru and (as shown in the example
> >above) must be mounted with great care to eliminate all possibility
> >of moisture behind the plate.  These systems are usually
> >professionally installed, custom designed for each boat, and cost
> >mucho bucks.  See
> >http://www.marinelightning.com/Information/GroundingGuide.htm for
> >some details on this.
> >
> >2) Static dissipators - These are like inverted stainless steel
> >"whisk brooms" attached to the top of your mast.  The theory is that
> >the many small metallic points offered by the strands of the device
> >will dissipate charges gradually as they build up, rather than
> >allowing potentials to increase to the level of a full strike.  There
> >seems to be little evidence that this actually works, since it's
> >supposed to prevent a strike.  So... you could say if you don't get
> >hit, it must be working!  They are cheap and have the added benefit
> >of keeping birds off your masthead.  See example at
> >http://www.yachtgard.com/lightning.html
> >
> >3) Mast grounding systems - These work on the same principal as #1
> >above, except the focus is entirely on the mast, rather than the
> >whole boat.  The idea being that if lighting strikes the mast (most
> >likely point), we should give it somewhere to go before it can cause
> >any damage.  In concept, this is similar to the "jumper cable" method
> >mentioned earlier, but approaches the problem in a more realistic
> >manner.  A large copper conductor is bolted to the mast and attached
> >to heavy copper cable, which can be removed and attached when needed,
> >leading into the water.  The water-end usually has some kind of
> >device attached to increase its surface area in contact with the
> >water.  See http://www.strikeshield.com/ for a commercial example.
> >
> >There are many online resources on lightning and boats, protection
> >systems, theories, rumors, innuendo... hey, after all it IS the
> >Internet ;-)  Try a search on "lightning protection for sailboats"
> >and you'll get plenty to confuse you further.
> >
> >And finally, to Mike W: there are two problems with your system - an
> >aluminum plate (1) with a right-angle bend in it (2).  You'd be much
> >better off with a flat copper plate attached to the conductor without
> >any bends.  I don't know what the physical constraints inside the
> >trunk are, but there you have it.
> >
> >Cheers!
> >
> >John
> >
> >"Ever wonder what the speed of lightning would be if it didn't zigzag?"
> >
> >
> >
> >__________________________________________________
> >Use Rhodes22-list at rhodes22.org, Help? www.rhodes22.org/list
>
>
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