A proa has been reported sailing in St Georges basin just South of
Nowra, NSW. About 30' or so, black hull with a red stripe. Any clues
as to its identity?
Robert

--- In harryproa@..., "Mark Stephens" <stephens@o...>
wrote:
> I just read a snippet in the newspaper about a fellow being struck
by lightning this week while sailing his Laser just north of Sydney.
It says he is recovering in hospital having been thrown 10 metres and
the hull has a large hole in it. It happens.
>
> Mark
>
> I think I had better give boating away and go back to bungee jumping.

Regards,

Jim

I just read a snippet in the newspaper about a fellow being struck by lightning
this week while sailing his Laser just north of Sydney. It says he is recovering
in hospital having been thrown 10 metres and the hull has a large hole in it. It
happens.

Mark


*************************
Mark Stephens
www.harryproa.com
stephens@...
(int. 61) 02 66552016


[Non-text portions of this message have been removed]

Correct, except for lightning is a time changing event, producing
a moving electro-magnetic wave, linearly polarized.  Which is
good when it's running down the mast.  If you know where it is
and where it is going the protective measures will be more
effective.  Polarization keeps that EMP from inducing current in
your wiring except for wires like antenna's that are aligned in the
same plane.  Those vertical circuits if still connected are toast !

Physical disconnect is a must for vertical wiring.  AND they have
to be isolated from nearby gear or they will arc........ guaranteed !
Either connect them to bonding strip or coil the ends into a very
good electrically insulated container.  Connecting to a bonding
strip is way better cause that induced current wants to go
somewhere thus seeking any possible escape to ground.  It only
takes a nick in the cable sheath for that dangerous current to
escape into the boat.

It's not pretty, my son was hit sitting in our living room.  Lightning
struck the chimney which has a metal insulating sleeve.   Side
flash came out of the flue and stuck him in the arm.  First time all
day that I could get him out of the couch from watching TV.  Too
bad he couldn't move his arm for hours and it really hurt.  That
chimney was no different than a mast, but it's connection to earth
ground was insufficient.   No lightning rod and I can envision an
even greater disaster at sea.

Regards,

JT

--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
> jitctaylor wrote
>   >
>   Lenz Law has to do with induced electric current while moving
a
>   conductor though an electric field.
>   Do you mean a magnetic field?
>
>
>   rgs
>   Tony
>
> [Non-text portions of this message have been removed]

jitctaylor wrote
   >
   Lenz Law has to do with induced electric current while moving a
   conductor though an electric field.
   Do you mean a magnetic field?


   rgs
   Tony

[Non-text portions of this message have been removed]

-I think I recall a picture of the Lithuanian one somewhere in the
proa files

Robert-- In harryproa@..., "rob denney" <proa@t...>
wrote:
> G'day,
>
> Nothing wrong with scepticism.
>
> The only Harryproa currently sailing that is not mine is the one in
Maine
> which we built and described in
> http://www.harryproa.com/building_hg/buildinghg_wk1_img1.htm and
following
> reports.  This boat was apparently launched just before the end of
last
> northern summer sails fast, works well, handles effortlessly and
tacks and
> shunts successfully.  Yet to go out in big seas or winds.   Check
out
> http://www.proasail.com/ for more information.
>
> There is Terho Halmes version, which has equal length hulls with the
> accommodation in the windward hull and a modified junk rig which
apparently
> works well ( I have not seen either of these boats sailing)
> http://kotisivu.mtv3.fi/terho.halme/ping-pong.html
>
> There are a bunch of traditional type proas, check out
> http://www.proafile.com/news.html.
>
> There is W, a 12m/40' cat I designed and built in New Zealand a few
years
> ago, which has an Easyrig in one hull, so is a proa half the time.
>
> There is a Lithuanian proa which looks very similar to a harryproa,
but I
> have mislaid the pictures.  This boat predates harry proas by
decades! It
> apparently worked well, also.
>
> And that's it, as far as I know.
>
> The next one sailing will almost certainly be the Visionarry
(15m/50 footer)
> we are building at Coff's Harbour, see progress reports on
www.harryproa.com
> Launching date is April, but no one will be surprised if the detail
work on
> a brand new type of boat pushes this out somewhat.  There is also
Blind Date
> (another Visionarry) , which could be launched this northern
summer.   There
> are also 16 other sets of plans sold, but none, as far as I know
will be
> launched in the next few months.
>
>
> Regards,
>
> Rob
>
>
> ----- Original Message -----
> From: "surryequip" <surryequipment@r...>
> To: <harryproa@...>
> Sent: Thursday, January 29, 2004 12:40 AM
> Subject: [harryproa] How many sailing?
>
>
> > I don't mean any harm, but how many harryproas are sailing not
just
> > building that don't belong to Rob Denney? I am fascinated by this
> > discussion but the world is full of naysayers and like the saying
> > goes- the proof is in the pudding
> >
> >
> > To unsubscribe from this group, send an email to:
> > harryproa-unsubscribe@...
> >
> >
> >
> > Your use of Yahoo! Groups is subject to
> http://au.docs.yahoo.com/info/terms/
> >
> >
> >

Tony,

I am planning a visionarry and the mast will pivot though 300
degrees.  Rob wants to put stays from mast to WW hull.

I would just disconnect the mast light cable completely and
attach it to one of the hull through bolts to grounding plate.
Personally I would only connect it when needed at anchor.

On my boat the steaming light is actually on the WW hull on top
of a stub mast.

Waste of time to use the mast light cable as any useful ground.
Better to just connect it to the ground plate or bonding strip when
not in use.   Hopefully it can survive the induced EMF from the
EMP.  Otherwise will need a new light AND wire.

JT

--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
> Question
> If you did have a conductor in/on the mast on a Harry how do
you envisage earthing it?(rotation of 360deg)
> Would you have a terminal at the base of the mast and when
storms are near bolt on your cable (of appropriate length)and
throw it over the side for earthing purposes?
> Rgs
> Tony
>   ----- Original Message -----
>   From: jjtctaylor
>   To: harryproa@...
>   Sent: Thursday, January 29, 2004 12:42 PM
>   Subject: [harryproa] Re: lightning and carbon masts
>
>
>   Tony,
>
>   Don't think induced current from EMF/ EMP from the primary
>   leader will be cause for damage, but the side flashes that
enter
>   the circuitry is a more probable culprit.  The primary leader is
>   coming down vertically, all your boat wiring except the
antennas
>   and mast lights should be running horizontal and no closer
than
>   6 feet to the mast.  So the pudent sailor physically
disconnects
>   the antenna leads and mast cable.    Antennas and mast
lights
>   are usually a total loss if struck anyway.
>
>   But the vertical lightning leader is moving the wrong direction
to
>   impart a current into other shipboard systems.  It's the pesky
>   side flashes that can be induced into your electrical circuitry.
AS
>   you said most sailors are not likely to disconnect the miles of
>   wiring from your senstive electronics.  Perhaps choose wisely
a
>   limited electronics package to completely isolate and hope for
>   the best with the rest of it.  A proper grounding system should
>   keep the boat occupants safe and that is what counts most
>   anyway.  That's my plan & I am sticking with it.  Buy some
>   insurance or keep bucks around for that rainy night.  (Hand
held
>   GPS and VHF radio are handy too as back-ups)
>
>   Regards,
>
>   JT
>
>   --- In harryproa@..., "Tony Richardson"
>   <atrichardson@b...> wrote:
>   > I agree a faraday cage would be good to put around your
>   electronics.
>   > But the wiring in most boats forms a spiders web and in
most
>   cases they all lead to a common area that would be very
close to
>   the electronics you are trying to protect if not actually
connected
>   to them. The EMF (electro magnetic force) from the lightning
>   would create a massive current through this web and it would
all
>   lead to the power supply/electronics area. The resultant surge
is
>   enough to pop most electronic devices.
>   > So the only solution would be to remove your electronics
and
>   put them in an earthed metal enclosure.
>   > Have you ever tried to remove a piece of electronic
equipment
>   in a big hurry? and what happens to things like transducers,
>   antenna's etc that you can't pull out?do they survive?
>   > Encasing all wiring in wire braid would be the most
expensive
>   exercise possible on a boat. It may be necessary on planes to
>   stop them from crashing but it is almost unheard of in sailing
>   boats.
>   > I question the viability and economics of encasing the
wiring.
>   > Voltage surge devices may be the most practical solution
>   when used in conjunction with a cage setup that is
incorporated
>   into the electronics mounting structure.
>   > In the event of a strike I doubt many things are going to
survive
>   in operational form even after this.
>   > Just how would you test it as well?
>   > Sometimes shit happens regardless of the precautions
taken.
>   > Someone once told me(rob) it's not the problems you
>   anticipate and allow for that get you, its the ones you don't
even
>   realise exist that are the ones that will catch you out.
>   > Still so little is known about the effects of lightning
>   > Carbon or Alloy mast?
>   > Carbon is lighter and I'm pretty sure we are still building
boats
>   not lightning experiments
>   > Although its interesting information for us all
>   > Rgs
>   > Tony
>   >   ----- Original Message -----
>   >   From: Robert
>   >   To: harryproa@...
>   >   Sent: Thursday, January 29, 2004 9:23 AM
>   >   Subject: [harryproa] Re: lightning and carbon masts
>   >
>   >
>   >   Thanks Bob,
>   >   My understanding from the reading,
>   >   It seems that you can't prevent a strike but a suitable blunt
rod
>   at
>   >   the top of the mast attached to 4 gauge copperwire
grounded
>   in a 1
>   >   square foot of metal in salt water will give it a path without
too
>   >   much damage. All other metal fitting should be boded to
the
>   discharge
>   >   path and, if you can, turn off your electronics and enclose
>   them in a
>   >   Faraday cage ie something like a microwave ove, a metal
box
>   or
>   >   enclosed wire mesh. If you can't there are various method
to
>   reduce
>   >   damage such as twisting any input wires together and
putting
>   an
>   >   insulated metal mesh sleeve over them as well as
volatage
>   overload
>   >   devices.
>   >
>   >   For a low metal boat like a Harry, such a process shouldn't
be
>   too
>   >   onerous in saltwater but for fresh water it requires a much
>   larger
>   >   surface area of metal in the water and could be a pain,
though
>   I
>   >   suppose a copper bottom would save on antifouling.
>   >   Robert
>   >
>   >   --- In harryproa@..., "Grona Jr, Robert
J."
>   >   <PPL_RJG@e...> wrote:
>   >   > Try the following as back ground on lighting realizing that
>   carbon
>   >   > conducts high voltage and a strike will boil off the resin
>   binder.
>   >   If
>   >   > hit aluminum doesn't fair much better!
>   >   >
>   >   >
>   >   > http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
>   >   >
>   >   > http://plaza.ufl.edu/rakov/Gas.html
>   >   >
>   >   > http://www.thomson.ece.ufl.edu/lightning/
>   >   >
>   >   > http://www.lightning.ece.ufl.edu/
>   >   >
>   >   > Let us know the results of your research, Bob G.
>   >   >
>   >   >
>   >   >
>   >   >  -----Original Message-----
>   >   > From: Robert [mailto:cateran1949@y...]
>   >   > Sent: Tuesday, January 27, 2004 10:11 PM
>   >   > To: harryproa@...
>   >   > Subject: [harryproa] Re: lightning and carbon masts
>   >   >
>   >   >  snip ---------------------
>   >   >
>   >   > You paint a pretty scary picture of what can happen. Has
>   there been
>   >   > any work on insulating against strikes, bringing them into
>   the
>   >   domain
>   >   > of fibreglass or wooden ones
>   >   >
>   >   > Appreciate the research
>   >   >
>   >   > Robert---
>   >   >
>   >   >
>   >   >
>   >   >
>   >   >
>   >   > [Non-text portions of this message have been removed]
>   >
>   >
>   >
>   >   To unsubscribe from this group, send an email to:
>   >   harryproa-unsubscribe@...
>   >
>   >
>   >
>   >
>   >   Your use of Yahoo! Groups is subject to the Yahoo! Terms
of
>   Service.
>   >
>   >
>   > [Non-text portions of this message have been removed]
>
>
>
>   To unsubscribe from this group, send an email to:
>   harryproa-unsubscribe@...
>
>
>
>
>   Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service.
>
>
> [Non-text portions of this message have been removed]

EMF/ EMP are related to each other.  But the issue is how does it
work.  The leader whether side flash or main strike creates a
current over a very short period, thus the idea of pulse.  Moving
current always creates a magnetic filed around it.  By Faradays
Law if a wire moves through a magnetic field a voltage is
induced.  In this case the magnetic field is what is moving
(outward from the strike)  If the wire make a circuit then we have
current too.  Current is BAD.

Induced voltage doesn't happen willy-nilly and everywhere.  The
conductor must be aligned to right angle to the magnetic field
which means parallel to the lightning leader.  THis is why
bonding strips and boat wiring MUST be horizontal.  Otherwise
they would pick up the EMP and transmit the induced EMF to your
circuitry.    That is also why radios are smoked so often in a
lightning event.  The EMF/ EMP was picked up by the antenna
and ruined the receiver section and if you have mosfets as is
typical for final amplifier transistors they went too.

I have seen plenty of hard drives non-functional after a lightning
event.  Almost all losses were the drive controllers, from induced
surges through the power grid, telephone, cable or whatever.  I
have never seen a drive platter erased.

Granted if you have your PC backed up against the mast you can
expect smoke coming out of everywhere.  If the drive is horizontal
and located at the nav station I expect no impact to content.
However if side flashes are present or you failed to disconnect
the antennas, then some damage to sensitive gear is likely.

You can only do what is prudent and cost effective.  Everyone will
tell you surge protection from a side flash or leader is useless.
However those devises can stop emf from running into the
equipment.

Regards,

JT

--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
> You wrote
>
>   Tony,
>
>   Don't think induced current from EMF/ EMP from the primary
>   leader will be cause for damage, but the side flashes that
enter
>   the circuitry is a more probable culprit.
>
>   Then why have the cage
>   The purpose of the cage is to arrest (for want of a better word)
the EMF I thought
>   The induced EMF in electronic units is usually the cause of
damage to units in isolation but unprotected/caged
>   (starting to reach the extent of my knowlege here so I might
wander a bit)
>   A strike near a PC will render it useless because the
harddrive gets wiped due to the Magnetic influence (EMF)
>   Even though it didn't directly get hit.
>   The same thing could happen to anything that uses any form
of memory to operate (RAM or ROM)
>   Other semiconductor based equipment may fair a little better
but typically you would expect damage to some componentry
through EMF I would have thought. Transformers and capacitors
would be a certain target for this and to a lesser degree diodes.
>
>
>
>    The primary leader is
>   coming down vertically, all your boat wiring except the
antennas
>   and mast lights should be running horizontal and no closer
than
>   6 feet to the mast.
>
>   If my memory of magnetic fields with electricity is correct then
the fields radiate out in all directions
>   Dissapation of EMF over distance is very hard to judge with
lightning due to the diverse nature of it.
>   So I fail to see the relation of Vertical to horizontal orientation. I
would have thought size and volume of wireing has a greater
influence.
>   Where the lightning comes across resistance ie your mast I
would assume the increase in current required at the resistance
point for conductivity to occure would increase the EMF as well
>
>    So the pudent sailor physically disconnects
>   the antenna leads and mast cable.
>
>   But still has the possibility of damage without a cage
>
>   Antennas and mast lights
>   are usually a total loss if struck anyway.
>
>   So radio is useless anyway
>
>
>   But the vertical lightning leader is moving the wrong direction
to
>   impart a current into other shipboard systems.
>
>   I cant see how as any current creates an EMF. Even when
running down the lightning conductor
>    It's the pesky
>   side flashes that can be induced into your electrical circuitry.
>    AS
>   you said most sailors are not likely to disconnect the miles of
>   wiring from your senstive electronics.  Perhaps choose wisely
a
>   limited electronics package to completely isolate and hope for
>   the best with the rest of it.
>
>   Agreed
>
>     A proper grounding system should
>   keep the boat occupants safe and that is what counts most
>   anyway.
>
>   Definatly
>
>    That's my plan & I am sticking with it.  Buy some
>   insurance or keep bucks around for that rainy night.  (Hand
held
>   GPS and VHF radio are handy too as back-ups)
>
>   I question the need to modify anything given the added cost
>   As you said buy some insurance with the money saved and
get a new one when needed.
>   Because if you do get struck there is no certainty that you will
get away without damage even with all the modifications
>
>   Rgs
>   Tony
>
>
> [Non-text portions of this message have been removed]

>
> A purely technical query on the theory. Is it inertia or is it Lenz's
> Law or possibly a combination of?
>
Lenz Law has to do with induced electric current while moving a
conductor though an electric field.  The side flashes are purely
Newtonian issues.  Although it is not purely mechanical cause
some part of the electrical path remains a plasma effect which is
not well understood.


Regards,

JT

G'day,

Nothing wrong with scepticism.

The only Harryproa currently sailing that is not mine is the one in Maine
which we built and described in
http://www.harryproa.com/building_hg/buildinghg_wk1_img1.htm and following
reports.  This boat was apparently launched just before the end of last
northern summer sails fast, works well, handles effortlessly and tacks and
shunts successfully.  Yet to go out in big seas or winds.   Check out
http://www.proasail.com/ for more information.

There is Terho Halmes version, which has equal length hulls with the
accommodation in the windward hull and a modified junk rig which apparently
works well ( I have not seen either of these boats sailing)
http://kotisivu.mtv3.fi/terho.halme/ping-pong.html

There are a bunch of traditional type proas, check out
http://www.proafile.com/news.html.

There is W, a 12m/40' cat I designed and built in New Zealand a few years
ago, which has an Easyrig in one hull, so is a proa half the time.

There is a Lithuanian proa which looks very similar to a harryproa, but I
have mislaid the pictures.  This boat predates harry proas by decades! It
apparently worked well, also.

And that's it, as far as I know.

The next one sailing will almost certainly be the Visionarry (15m/50 footer)
we are building at Coff's Harbour, see progress reports on www.harryproa.com
Launching date is April, but no one will be surprised if the detail work on
a brand new type of boat pushes this out somewhat.  There is also Blind Date
(another Visionarry) , which could be launched this northern summer.   There
are also 16 other sets of plans sold, but none, as far as I know will be
launched in the next few months.


Regards,

Rob


----- Original Message -----
From: "surryequip" <surryequipment@...>
To: <harryproa@...>
Sent: Thursday, January 29, 2004 12:40 AM
Subject: [harryproa] How many sailing?


> I don't mean any harm, but how many harryproas are sailing not just
> building that don't belong to Rob Denney? I am fascinated by this
> discussion but the world is full of naysayers and like the saying
> goes- the proof is in the pudding
>
>
> To unsubscribe from this group, send an email to:
> harryproa-unsubscribe@...
>
>
>
> Your use of Yahoo! Groups is subject to
http://au.docs.yahoo.com/info/terms/
>
>
>

--- In harryproa@..., "jjtctaylor" <jtaylor412@c...>
wrote:
> Robert,
>
> The more you can do to minimize your losses the better.  Biggest
> bang for the buck is getting that charge from mast top to water
> with as few turns or twists as possible.  I design machinery,
> most which use high high voltage drivers.   Those electrons
> once moving do not want to turn, momentum keeps 'em headed
> in one direction (mostly).  They may have low mass but they have
> some so inertia takes over.

A purely technical query on the theory. Is it inertia or is it Lenz's
Law or possibly a combination of?




   If the lightning strike has to
> overcome boundaries, bends or restrictions they will fly off with
> very dangerous side flashes,...... (the stuff that kills).   Rob
has
> plans for my mast to include insulating internal mast sections to
> stand off the lighning rod.  I plan to use 3/8 - 1/2 inch copper
> pipe.  It has as good or better the surface area of 4 AWG
> stranded cable.

Sounds like a good move. In my understanding a pipe would be a lot
better than a cable because at that voltage the current is carried in
the outer levels of the conductor as the electrons are trying to keep
away from each other.



>
> Rob will also put the mast light cable in an insulating sleeve of
> PVC or some other conduit.  Have to keep halyards, wires, etc
> from chafing on each other.
>
> You are correct in all your statements below, don't forget the
> bonding strip the runs horizontal to connect all the non- current
> carrying grounds AND all the major metal stuff, gensets, and
> external metal chainplates, helm wheel, etc.  That too is
> connected to the thru bolt for the ground plate.  If there are side
> flashes the bonding strip will safely draw the current away from
> sensitive stuff.
>
> If you are making faraday cages (metal bins or whatever) they get
> connected to bonding strip.  Don't isolate them, those would
> make nasty capacitors if they become highly charged.

Ouch!
I presume this is where one puts the hand held GPS and EPIRB. I also
was under the impresion that the EMF pulse can upset the storage of
data.

Thanks,
  Robert

>
> Regards,
>
> JT
>
> --- In harryproa@..., "Robert"
> <cateran1949@y...> wrote:
> > Thanks Bob,
> > My understanding from the reading,
> > It seems that you can't prevent a strike but a suitable blunt rod
> at
> > the top of the mast attached to 4 gauge copperwire grounded
> in a 1
> > square foot of metal in salt water will give it a path without
too
> > much damage. All other metal fitting should be boded to the
> discharge
> > path and, if you can, turn off your electronics and enclose them
> in a
> > Faraday cage ie something like a microwave ove, a metal box
> or
> > enclosed wire mesh. If you can't there are various method to
> reduce
> > damage such as twisting any input wires together and putting
> an
> > insulated metal mesh sleeve over them as well as volatage
> overload
> > devices.
> >
> > For a low metal boat like a Harry, such a process shouldn't be
> too
> > onerous in saltwater but for fresh water it requires a much
> larger
> > surface area of metal in the water and could be a pain, though I
> > suppose a copper bottom would save on antifouling.
> > Robert
> >
> >  --- In harryproa@..., "Grona Jr, Robert J."
> > <PPL_RJG@e...> wrote:
> > > Try the following as back ground on lighting realizing that
> carbon
> > > conducts high voltage and a strike will boil off the resin
> binder.
> > If
> > > hit aluminum doesn't fair much better!
> > >
> > >
> > > http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
> > >
> > > http://plaza.ufl.edu/rakov/Gas.html
> > >
> > > http://www.thomson.ece.ufl.edu/lightning/
> > >
> > > http://www.lightning.ece.ufl.edu/
> > >
> > > Let us know the results of your research, Bob G.
> > >
> > >
> > >
> > >  -----Original Message-----
> > > From: Robert [mailto:cateran1949@y...]
> > > Sent: Tuesday, January 27, 2004 10:11 PM
> > > To: harryproa@...
> > > Subject: [harryproa] Re: lightning and carbon masts
> > >
> > >  snip ---------------------
> > >
> > > You paint a pretty scary picture of what can happen. Has
> there been
> > > any work on insulating against strikes, bringing them into the
> > domain
> > > of fibreglass or wooden ones
> > >
> > > Appreciate the research
> > >
> > > Robert---
> > >
> > >
> > >
> > >
> > >
> > > [Non-text portions of this message have been removed]

Question
If you did have a conductor in/on the mast on a Harry how do you envisage
earthing it?(rotation of 360deg)
Would you have a terminal at the base of the mast and when storms are near bolt
on your cable (of appropriate length)and throw it over the side for earthing
purposes?
Rgs
Tony
   ----- Original Message -----
   From: jjtctaylor
   To: harryproa@...
   Sent: Thursday, January 29, 2004 12:42 PM
   Subject: [harryproa] Re: lightning and carbon masts


   Tony,

   Don't think induced current from EMF/ EMP from the primary
   leader will be cause for damage, but the side flashes that enter
   the circuitry is a more probable culprit.  The primary leader is
   coming down vertically, all your boat wiring except the antennas
   and mast lights should be running horizontal and no closer than
   6 feet to the mast.  So the pudent sailor physically disconnects
   the antenna leads and mast cable.    Antennas and mast lights
   are usually a total loss if struck anyway.

   But the vertical lightning leader is moving the wrong direction to
   impart a current into other shipboard systems.  It's the pesky
   side flashes that can be induced into your electrical circuitry.  AS
   you said most sailors are not likely to disconnect the miles of
   wiring from your senstive electronics.  Perhaps choose wisely a
   limited electronics package to completely isolate and hope for
   the best with the rest of it.  A proper grounding system should
   keep the boat occupants safe and that is what counts most
   anyway.  That's my plan & I am sticking with it.  Buy some
   insurance or keep bucks around for that rainy night.  (Hand held
   GPS and VHF radio are handy too as back-ups)

   Regards,

   JT

   --- In harryproa@..., "Tony Richardson"
   <atrichardson@b...> wrote:
   > I agree a faraday cage would be good to put around your
   electronics.
   > But the wiring in most boats forms a spiders web and in most
   cases they all lead to a common area that would be very close to
   the electronics you are trying to protect if not actually connected
   to them. The EMF (electro magnetic force) from the lightning
   would create a massive current through this web and it would all
   lead to the power supply/electronics area. The resultant surge is
   enough to pop most electronic devices.
   > So the only solution would be to remove your electronics and
   put them in an earthed metal enclosure.
   > Have you ever tried to remove a piece of electronic equipment
   in a big hurry? and what happens to things like transducers,
   antenna's etc that you can't pull out?do they survive?
   > Encasing all wiring in wire braid would be the most expensive
   exercise possible on a boat. It may be necessary on planes to
   stop them from crashing but it is almost unheard of in sailing
   boats.
   > I question the viability and economics of encasing the wiring.
   > Voltage surge devices may be the most practical solution
   when used in conjunction with a cage setup that is incorporated
   into the electronics mounting structure.
   > In the event of a strike I doubt many things are going to survive
   in operational form even after this.
   > Just how would you test it as well?
   > Sometimes shit happens regardless of the precautions taken.
   > Someone once told me(rob) it's not the problems you
   anticipate and allow for that get you, its the ones you don't even
   realise exist that are the ones that will catch you out.
   > Still so little is known about the effects of lightning
   > Carbon or Alloy mast?
   > Carbon is lighter and I'm pretty sure we are still building boats
   not lightning experiments
   > Although its interesting information for us all
   > Rgs
   > Tony
   >   ----- Original Message -----
   >   From: Robert
   >   To: harryproa@...
   >   Sent: Thursday, January 29, 2004 9:23 AM
   >   Subject: [harryproa] Re: lightning and carbon masts
   >
   >
   >   Thanks Bob,
   >   My understanding from the reading,
   >   It seems that you can't prevent a strike but a suitable blunt rod
   at
   >   the top of the mast attached to 4 gauge copperwire grounded
   in a 1
   >   square foot of metal in salt water will give it a path without too
   >   much damage. All other metal fitting should be boded to the
   discharge
   >   path and, if you can, turn off your electronics and enclose
   them in a
   >   Faraday cage ie something like a microwave ove, a metal box
   or
   >   enclosed wire mesh. If you can't there are various method to
   reduce
   >   damage such as twisting any input wires together and putting
   an
   >   insulated metal mesh sleeve over them as well as volatage
   overload
   >   devices.
   >
   >   For a low metal boat like a Harry, such a process shouldn't be
   too
   >   onerous in saltwater but for fresh water it requires a much
   larger
   >   surface area of metal in the water and could be a pain, though
   I
   >   suppose a copper bottom would save on antifouling.
   >   Robert
   >
   >   --- In harryproa@..., "Grona Jr, Robert J."
   >   <PPL_RJG@e...> wrote:
   >   > Try the following as back ground on lighting realizing that
   carbon
   >   > conducts high voltage and a strike will boil off the resin
   binder.
   >   If
   >   > hit aluminum doesn't fair much better!
   >   >
   >   >
   >   > http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
   >   >
   >   > http://plaza.ufl.edu/rakov/Gas.html
   >   >
   >   > http://www.thomson.ece.ufl.edu/lightning/
   >   >
   >   > http://www.lightning.ece.ufl.edu/
   >   >
   >   > Let us know the results of your research, Bob G.
   >   >
   >   >
   >   >
   >   >  -----Original Message-----
   >   > From: Robert [mailto:cateran1949@y...]
   >   > Sent: Tuesday, January 27, 2004 10:11 PM
   >   > To: harryproa@...
   >   > Subject: [harryproa] Re: lightning and carbon masts
   >   >
   >   >  snip ---------------------
   >   >
   >   > You paint a pretty scary picture of what can happen. Has
   there been
   >   > any work on insulating against strikes, bringing them into
   the
   >   domain
   >   > of fibreglass or wooden ones
   >   >
   >   > Appreciate the research
   >   >
   >   > Robert---
   >   >
   >   >
   >   >
   >   >
   >   >
   >   > [Non-text portions of this message have been removed]
   >
   >
   >
   >   To unsubscribe from this group, send an email to:
   >   harryproa-unsubscribe@...
   >
   >
   >
   >
   >   Your use of Yahoo! Groups is subject to the Yahoo! Terms of
   Service.
   >
   >
   > [Non-text portions of this message have been removed]



   To unsubscribe from this group, send an email to:
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[Non-text portions of this message have been removed]

You wrote

   Tony,

   Don't think induced current from EMF/ EMP from the primary
   leader will be cause for damage, but the side flashes that enter
   the circuitry is a more probable culprit.

   Then why have the cage
   The purpose of the cage is to arrest (for want of a better word) the EMF I
thought
   The induced EMF in electronic units is usually the cause of damage to units in
isolation but unprotected/caged
   (starting to reach the extent of my knowlege here so I might wander a bit)
   A strike near a PC will render it useless because the harddrive gets wiped due
to the Magnetic influence (EMF)
   Even though it didn't directly get hit.
   The same thing could happen to anything that uses any form of memory to
operate (RAM or ROM)
   Other semiconductor based equipment may fair a little better but typically you
would expect damage to some componentry through EMF I would have thought.
Transformers and capacitors would be a certain target for this and to a lesser
degree diodes.



    The primary leader is
   coming down vertically, all your boat wiring except the antennas
   and mast lights should be running horizontal and no closer than
   6 feet to the mast.

   If my memory of magnetic fields with electricity is correct then the fields
radiate out in all directions
   Dissapation of EMF over distance is very hard to judge with lightning due to
the diverse nature of it.
   So I fail to see the relation of Vertical to horizontal orientation. I would
have thought size and volume of wireing has a greater influence.
   Where the lightning comes across resistance ie your mast I would assume the
increase in current required at the resistance point for conductivity to occure
would increase the EMF as well

    So the pudent sailor physically disconnects
   the antenna leads and mast cable.

   But still has the possibility of damage without a cage

   Antennas and mast lights
   are usually a total loss if struck anyway.

   So radio is useless anyway


   But the vertical lightning leader is moving the wrong direction to
   impart a current into other shipboard systems.

   I cant see how as any current creates an EMF. Even when running down the
lightning conductor
    It's the pesky
   side flashes that can be induced into your electrical circuitry.
    AS
   you said most sailors are not likely to disconnect the miles of
   wiring from your senstive electronics.  Perhaps choose wisely a
   limited electronics package to completely isolate and hope for
   the best with the rest of it.

   Agreed

     A proper grounding system should
   keep the boat occupants safe and that is what counts most
   anyway.

   Definatly

    That's my plan & I am sticking with it.  Buy some
   insurance or keep bucks around for that rainy night.  (Hand held
   GPS and VHF radio are handy too as back-ups)

   I question the need to modify anything given the added cost
   As you said buy some insurance with the money saved and get a new one when
needed.
   Because if you do get struck there is no certainty that you will get away
without damage even with all the modifications

   Rgs
   Tony


[Non-text portions of this message have been removed]

Tony,

Don't think induced current from EMF/ EMP from the primary
leader will be cause for damage, but the side flashes that enter
the circuitry is a more probable culprit.  The primary leader is
coming down vertically, all your boat wiring except the antennas
and mast lights should be running horizontal and no closer than
6 feet to the mast.  So the pudent sailor physically disconnects
the antenna leads and mast cable.    Antennas and mast lights
are usually a total loss if struck anyway.

But the vertical lightning leader is moving the wrong direction to
impart a current into other shipboard systems.  It's the pesky
side flashes that can be induced into your electrical circuitry.  AS
you said most sailors are not likely to disconnect the miles of
wiring from your senstive electronics.  Perhaps choose wisely a
limited electronics package to completely isolate and hope for
the best with the rest of it.  A proper grounding system should
keep the boat occupants safe and that is what counts most
anyway.  That's my plan & I am sticking with it.  Buy some
insurance or keep bucks around for that rainy night.  (Hand held
GPS and VHF radio are handy too as back-ups)

Regards,

JT

--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
> I agree a faraday cage would be good to put around your
electronics.
> But the wiring in most boats forms a spiders web and in most
cases they all lead to a common area that would be very close to
the electronics you are trying to protect if not actually connected
to them. The EMF (electro magnetic force) from the lightning
would create a massive current through this web and it would all
lead to the power supply/electronics area. The resultant surge is
enough to pop most electronic devices.
> So the only solution would be to remove your electronics and
put them in an earthed metal enclosure.
> Have you ever tried to remove a piece of electronic equipment
in a big hurry? and what happens to things like transducers,
antenna's etc that you can't pull out?do they survive?
> Encasing all wiring in wire braid would be the most expensive
exercise possible on a boat. It may be necessary on planes to
stop them from crashing but it is almost unheard of in sailing
boats.
> I question the viability and economics of encasing the wiring.
> Voltage surge devices may be the most practical solution
when used in conjunction with a cage setup that is incorporated
into the electronics mounting structure.
> In the event of a strike I doubt many things are going to survive
in operational form even after this.
> Just how would you test it as well?
> Sometimes shit happens regardless of the precautions taken.
> Someone once told me(rob) it's not the problems you
anticipate and allow for that get you, its the ones you don't even
realise exist that are the ones that will catch you out.
> Still so little is known about the effects of lightning
> Carbon or Alloy mast?
> Carbon is lighter and I'm pretty sure we are still building boats
not lightning experiments
> Although its interesting information for us all
> Rgs
> Tony
>   ----- Original Message -----
>   From: Robert
>   To: harryproa@...
>   Sent: Thursday, January 29, 2004 9:23 AM
>   Subject: [harryproa] Re: lightning and carbon masts
>
>
>   Thanks Bob,
>   My understanding from the reading,
>   It seems that you can't prevent a strike but a suitable blunt rod
at
>   the top of the mast attached to 4 gauge copperwire grounded
in a 1
>   square foot of metal in salt water will give it a path without too
>   much damage. All other metal fitting should be boded to the
discharge
>   path and, if you can, turn off your electronics and enclose
them in a
>   Faraday cage ie something like a microwave ove, a metal box
or
>   enclosed wire mesh. If you can't there are various method to
reduce
>   damage such as twisting any input wires together and putting
an
>   insulated metal mesh sleeve over them as well as volatage
overload
>   devices.
>
>   For a low metal boat like a Harry, such a process shouldn't be
too
>   onerous in saltwater but for fresh water it requires a much
larger
>   surface area of metal in the water and could be a pain, though
I
>   suppose a copper bottom would save on antifouling.
>   Robert
>
>   --- In harryproa@..., "Grona Jr, Robert J."
>   <PPL_RJG@e...> wrote:
>   > Try the following as back ground on lighting realizing that
carbon
>   > conducts high voltage and a strike will boil off the resin
binder.
>   If
>   > hit aluminum doesn't fair much better!
>   >
>   >
>   > http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
>   >
>   > http://plaza.ufl.edu/rakov/Gas.html
>   >
>   > http://www.thomson.ece.ufl.edu/lightning/
>   >
>   > http://www.lightning.ece.ufl.edu/
>   >
>   > Let us know the results of your research, Bob G.
>   >
>   >
>   >
>   >  -----Original Message-----
>   > From: Robert [mailto:cateran1949@y...]
>   > Sent: Tuesday, January 27, 2004 10:11 PM
>   > To: harryproa@...
>   > Subject: [harryproa] Re: lightning and carbon masts
>   >
>   >  snip ---------------------
>   >
>   > You paint a pretty scary picture of what can happen. Has
there been
>   > any work on insulating against strikes, bringing them into
the
>   domain
>   > of fibreglass or wooden ones
>   >
>   > Appreciate the research
>   >
>   > Robert---
>   >
>   >
>   >
>   >
>   >
>   > [Non-text portions of this message have been removed]
>
>
>
>   To unsubscribe from this group, send an email to:
>   harryproa-unsubscribe@...
>
>
>
>
>   Your use of Yahoo! Groups is subject to the Yahoo! Terms of
Service.
>
>
> [Non-text portions of this message have been removed]

Robert,

The more you can do to minimize your losses the better.  Biggest
bang for the buck is getting that charge from mast top to water
with as few turns or twists as possible.  I design machinery,
most which use high high voltage drivers.   Those electrons
once moving do not want to turn, momentum keeps 'em headed
in one direction (mostly).  They may have low mass but they have
some so inertia takes over.  If the lightning strike has to
overcome boundaries, bends or restrictions they will fly off with
very dangerous side flashes,...... (the stuff that kills).   Rob has
plans for my mast to include insulating internal mast sections to
stand off the lighning rod.  I plan to use 3/8 - 1/2 inch copper
pipe.  It has as good or better the surface area of 4 AWG
stranded cable.

Rob will also put the mast light cable in an insulating sleeve of
PVC or some other conduit.  Have to keep halyards, wires, etc
from chafing on each other.

You are correct in all your statements below, don't forget the
bonding strip the runs horizontal to connect all the non- current
carrying grounds AND all the major metal stuff, gensets, and
external metal chainplates, helm wheel, etc.  That too is
connected to the thru bolt for the ground plate.  If there are side
flashes the bonding strip will safely draw the current away from
sensitive stuff.

If you are making faraday cages (metal bins or whatever) they get
connected to bonding strip.  Don't isolate them, those would
make nasty capacitors if they become highly charged.

Regards,

JT

--- In harryproa@..., "Robert"
<cateran1949@y...> wrote:
> Thanks Bob,
> My understanding from the reading,
> It seems that you can't prevent a strike but a suitable blunt rod
at
> the top of the mast attached to 4 gauge copperwire grounded
in a 1
> square foot of metal in salt water will give it a path without too
> much damage. All other metal fitting should be boded to the
discharge
> path and, if you can, turn off your electronics and enclose them
in a
> Faraday cage ie something like a microwave ove, a metal box
or
> enclosed wire mesh. If you can't there are various method to
reduce
> damage such as twisting any input wires together and putting
an
> insulated metal mesh sleeve over them as well as volatage
overload
> devices.
>
> For a low metal boat like a Harry, such a process shouldn't be
too
> onerous in saltwater but for fresh water it requires a much
larger
> surface area of metal in the water and could be a pain, though I
> suppose a copper bottom would save on antifouling.
> Robert
>
>  --- In harryproa@..., "Grona Jr, Robert J."
> <PPL_RJG@e...> wrote:
> > Try the following as back ground on lighting realizing that
carbon
> > conducts high voltage and a strike will boil off the resin
binder.
> If
> > hit aluminum doesn't fair much better!
> >
> >
> > http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
> >
> > http://plaza.ufl.edu/rakov/Gas.html
> >
> > http://www.thomson.ece.ufl.edu/lightning/
> >
> > http://www.lightning.ece.ufl.edu/
> >
> > Let us know the results of your research, Bob G.
> >
> >
> >
> >  -----Original Message-----
> > From: Robert [mailto:cateran1949@y...]
> > Sent: Tuesday, January 27, 2004 10:11 PM
> > To: harryproa@...
> > Subject: [harryproa] Re: lightning and carbon masts
> >
> >  snip ---------------------
> >
> > You paint a pretty scary picture of what can happen. Has
there been
> > any work on insulating against strikes, bringing them into the
> domain
> > of fibreglass or wooden ones
> >
> > Appreciate the research
> >
> > Robert---
> >
> >
> >
> >
> >
> > [Non-text portions of this message have been removed]

I agree a faraday cage would be good to put around your electronics.
But the wiring in most boats forms a spiders web and in most cases they all lead
to a common area that would be very close to the electronics you are trying to
protect if not actually connected to them. The EMF (electro magnetic force) from
the lightning would create a massive current through this web and it would all
lead to the power supply/electronics area. The resultant surge is enough to pop
most electronic devices.
So the only solution would be to remove your electronics and put them in an
earthed metal enclosure.
Have you ever tried to remove a piece of electronic equipment in a big hurry?
and what happens to things like transducers, antenna's etc that you can't pull
out?do they survive?
Encasing all wiring in wire braid would be the most expensive exercise possible
on a boat. It may be necessary on planes to stop them from crashing but it is
almost unheard of in sailing boats.
I question the viability and economics of encasing the wiring.
Voltage surge devices may be the most practical solution when used in
conjunction with a cage setup that is incorporated into the electronics mounting
structure.
In the event of a strike I doubt many things are going to survive in operational
form even after this.
Just how would you test it as well?
Sometimes shit happens regardless of the precautions taken.
Someone once told me(rob) it's not the problems you anticipate and allow for
that get you, its the ones you don't even realise exist that are the ones that
will catch you out.
Still so little is known about the effects of lightning
Carbon or Alloy mast?
Carbon is lighter and I'm pretty sure we are still building boats not lightning
experiments
Although its interesting information for us all
Rgs
Tony
   ----- Original Message -----
   From: Robert
   To: harryproa@...
   Sent: Thursday, January 29, 2004 9:23 AM
   Subject: [harryproa] Re: lightning and carbon masts


   Thanks Bob,
   My understanding from the reading,
   It seems that you can't prevent a strike but a suitable blunt rod at
   the top of the mast attached to 4 gauge copperwire grounded in a 1
   square foot of metal in salt water will give it a path without too
   much damage. All other metal fitting should be boded to the discharge
   path and, if you can, turn off your electronics and enclose them in a
   Faraday cage ie something like a microwave ove, a metal box or
   enclosed wire mesh. If you can't there are various method to reduce
   damage such as twisting any input wires together and putting an
   insulated metal mesh sleeve over them as well as volatage overload
   devices.

   For a low metal boat like a Harry, such a process shouldn't be too
   onerous in saltwater but for fresh water it requires a much larger
   surface area of metal in the water and could be a pain, though I
   suppose a copper bottom would save on antifouling.
   Robert

   --- In harryproa@..., "Grona Jr, Robert J."
   <PPL_RJG@e...> wrote:
   > Try the following as back ground on lighting realizing that carbon
   > conducts high voltage and a strike will boil off the resin binder.
   If
   > hit aluminum doesn't fair much better!
   >
   >
   > http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
   >
   > http://plaza.ufl.edu/rakov/Gas.html
   >
   > http://www.thomson.ece.ufl.edu/lightning/
   >
   > http://www.lightning.ece.ufl.edu/
   >
   > Let us know the results of your research, Bob G.
   >
   >
   >
   >  -----Original Message-----
   > From: Robert [mailto:cateran1949@y...]
   > Sent: Tuesday, January 27, 2004 10:11 PM
   > To: harryproa@...
   > Subject: [harryproa] Re: lightning and carbon masts
   >
   >  snip ---------------------
   >
   > You paint a pretty scary picture of what can happen. Has there been
   > any work on insulating against strikes, bringing them into the
   domain
   > of fibreglass or wooden ones
   >
   > Appreciate the research
   >
   > Robert---
   >
   >
   >
   >
   >
   > [Non-text portions of this message have been removed]



   To unsubscribe from this group, send an email to:
   harryproa-unsubscribe@...




   Your use of Yahoo! Groups is subject to the Yahoo! Terms of Service.


[Non-text portions of this message have been removed]

-There are at least two proas with the mast on the leeward hull
sailing but they have equal length hulls. I am about to build a
leeward hull to make a small Harry and there are some others who are
going for the equal length. I think all of them have had at least
Rob's influence, if not help, in the design. Give it a bit more time.
Robert


-- In harryproa@..., "surryequip"
<surryequipment@r...> wrote:
> I don't mean any harm, but how many harryproas are sailing not just
> building that don't belong to Rob Denney? I am fascinated by this
> discussion but the world is full of naysayers and like the saying
> goes- the proof is in the pudding

-There are at least two proas with the mast on the leeward hull
sailing but they have equal length hulls. I am about to build a
leeward hull to make a small Harry and there are some others who are
going for the equal length. I think all of them have had at least
Rob's influence, if not help, in the design. Give it a bit more time.
Robert


-- In harryproa@..., "surryequip"
<surryequipment@r...> wrote:
> I don't mean any harm, but how many harryproas are sailing not just
> building that don't belong to Rob Denney? I am fascinated by this
> discussion but the world is full of naysayers and like the saying
> goes- the proof is in the pudding

Thanks Bob,
My understanding from the reading,
It seems that you can't prevent a strike but a suitable blunt rod at
the top of the mast attached to 4 gauge copperwire grounded in a 1
square foot of metal in salt water will give it a path without too
much damage. All other metal fitting should be boded to the discharge
path and, if you can, turn off your electronics and enclose them in a
Faraday cage ie something like a microwave ove, a metal box or
enclosed wire mesh. If you can't there are various method to reduce
damage such as twisting any input wires together and putting an
insulated metal mesh sleeve over them as well as volatage overload
devices.

For a low metal boat like a Harry, such a process shouldn't be too
onerous in saltwater but for fresh water it requires a much larger
surface area of metal in the water and could be a pain, though I
suppose a copper bottom would save on antifouling.
Robert

  --- In harryproa@..., "Grona Jr, Robert J."
<PPL_RJG@e...> wrote:
> Try the following as back ground on lighting realizing that carbon
> conducts high voltage and a strike will boil off the resin binder.
If
> hit aluminum doesn't fair much better!
>
>
> http://www.thomson.ece.ufl.edu/lightning/SGEB17.html
>
> http://plaza.ufl.edu/rakov/Gas.html
>
> http://www.thomson.ece.ufl.edu/lightning/
>
> http://www.lightning.ece.ufl.edu/
>
> Let us know the results of your research, Bob G.
>
>
>
>  -----Original Message-----
> From: Robert [mailto:cateran1949@y...]
> Sent: Tuesday, January 27, 2004 10:11 PM
> To: harryproa@...
> Subject: [harryproa] Re: lightning and carbon masts
>
>  snip ---------------------
>
> You paint a pretty scary picture of what can happen. Has there been
> any work on insulating against strikes, bringing them into the
domain
> of fibreglass or wooden ones
>
> Appreciate the research
>
> Robert---
>
>
>
>
>
> [Non-text portions of this message have been removed]

Try the following as back ground on lighting realizing that carbon
conducts high voltage and a strike will boil off the resin binder. If
hit aluminum doesn't fair much better!


http://www.thomson.ece.ufl.edu/lightning/SGEB17.html

http://plaza.ufl.edu/rakov/Gas.html

http://www.thomson.ece.ufl.edu/lightning/

http://www.lightning.ece.ufl.edu/

Let us know the results of your research, Bob G.



  -----Original Message-----
From: Robert [mailto:cateran1949@...]
Sent: Tuesday, January 27, 2004 10:11 PM
To: harryproa@...
Subject: [harryproa] Re: lightning and carbon masts

  snip ---------------------

You paint a pretty scary picture of what can happen. Has there been
any work on insulating against strikes, bringing them into the domain
of fibreglass or wooden ones

Appreciate the research

Robert---





[Non-text portions of this message have been removed]

I don't mean any harm, but how many harryproas are sailing not just
building that don't belong to Rob Denney? I am fascinated by this
discussion but the world is full of naysayers and like the saying
goes- the proof is in the pudding

An aircraft is different from a mast. Around an aircraft you want to
provide a Faraday cage. For a mast you are accepting that the mast is
a possible conduit for lightning and trying to minimise damage by
providing an alternative pathway. A metal skinned mast still has to
discharge into the sea, I assume through the bottom of the boat.
Again there is the problem of metal through hull connections to avoid
blowing a hole. I see no advantage over a rod except for possibly
easier heat dissipation but that would probably be annulled with a
metal epoxy matrix.
You paint a pretty scary picture of what can happen. Has there been
any work on insulating against strikes, bringing them into the domain
of fibreglass or wooden ones

Appreciate the research

Robert---

  In harryproa@..., "jjtctaylor" <jtaylor412@c...>
wrote:
> Sorry no work with carbon fiber from natural lightning.   The
> Florida Lightning Research Center has been using military and
> commercial aircraft (Metal skin).  The government has figured
> out lighning and carbon fiber epoxies don't mix and are not likely
> to try airborne platforms just to have them explode and fall out of
> the sky.  Not a pretty picture.  What they have learned is kevlar
is
> a good surface shield and propogates electrical current more
> readily than carbon fiber/ epoxy.  (stealth fighter/ bomber stuff)
> Other aircraft firms promote the use of metal impregnated into
> the epoxy or a surface mesh of metal screen and epoxy.
>
> All adds weight and cost to your mast.  BUT possible solutions.
> Granted NOBODY has subjected their material to natural
> lightning.  They have just simulated the conductive properties by
> subjecting their coatings to 100KV arc from Tesla coils.  Not a
> true test of a a high voltage gas plasma conductive path.  Check
> the fine print/ warranty from these firms.
>
> They did do some research on lighning preventers and
> debunked the notion of bristle/ brush aerials as ion emitters for
> lightning dissipation.  They get hit as often and and what's worse
> is not only do they disintegrate  when struck but they do not
> provide a sufficient conduit to ground.  Net result is bristle/
brush
> aerials DO NOT protect the surrounding region from direct
> impact or side flashes.  In other word you are better off without a
> brush aerial.  The tried and tested blunt tip aerials still work
the
> best.  They may not prevent a strike but when hit they are more
> likely to take the current safely to ground.
>
> Otherwise maybe the metal mix epoxy and carbon fiber or metal
> mesh surface (painted or course) could be satisfactory.  That's
> what the aircraft industy is suggesting.  IN addition with the
> advent of weather radars and wind shear information, fewer
> lightning impacts are being reported.  Planes are staying away
> from problem storms.  Now if boats could do the same ?
>
> Regards,
>
> JT
>
> --- In harryproa@..., "Tony Richardson"
> <atrichardson@b...> wrote:
> >
> >   You wrote
> >   Most of their work has been sponsored by Aeronautical
> agencies
> >   and power companies.  Looking for damage/ impact to
> aircraft/
> >   towers, transmission lines, residential structures.  Not sure
> they
> >   have fried any boats or boat materials.  Interesting research
if
> not
> >   a little dangerous.
> >
> >   This is interesting because one of the modern materials in
> aircraft construction is carbon. The construction methods are
> similar to boat methods. They probably have some test data
> >   I would be interested in hearing the outcomes if you find any
> >   rgs
> >   Tony
> >
> >
> > [Non-text portions of this message have been removed]

It seems that an aluminium cable projected above the top of the mast
with a fibreglass rod and trailing in the water from another
fibreglass rod over the end of the boom should do the job. Now all I
need to know is how thick a cable and how much clearance from the
mast is needed as well as the strength of the fibreglass extension.
Either that or having the rod down the centre of the mastto an
external hull fitting. I can't see much problem in keeping contact
with a slip ring, especially considering the voltage. I would be
concerned about excessive heating and how to keep the rod insulated
from the inside of the mast. A covering insulation would blow at the
first strike. possibly an insulating disc every metre or so could do
the job.
It would certainly be good to see the research on the materials and
how much of a problem it is and whether it can be overcome by a layer
of light weight insulation.  --- In
harryproa@..., "Tony Richardson" <atrichardson@b...>
wrote:
>
>   You wrote
>   Most of their work has been sponsored by Aeronautical agencies
>   and power companies.  Looking for damage/ impact to aircraft/
>   towers, transmission lines, residential structures.  Not sure
they
>   have fried any boats or boat materials.  Interesting research if
not
>   a little dangerous.
>
>   This is interesting because one of the modern materials in
aircraft construction is carbon. The construction methods are similar
to boat methods. They probably have some test data
>   I would be interested in hearing the outcomes if you find any
>   rgs
>   Tony
>
>
> [Non-text portions of this message have been removed]

Sorry no work with carbon fiber from natural lightning.   The
Florida Lightning Research Center has been using military and
commercial aircraft (Metal skin).  The government has figured
out lighning and carbon fiber epoxies don't mix and are not likely
to try airborne platforms just to have them explode and fall out of
the sky.  Not a pretty picture.  What they have learned is kevlar is
a good surface shield and propogates electrical current more
readily than carbon fiber/ epoxy.  (stealth fighter/ bomber stuff)
Other aircraft firms promote the use of metal impregnated into
the epoxy or a surface mesh of metal screen and epoxy.

All adds weight and cost to your mast.  BUT possible solutions.
Granted NOBODY has subjected their material to natural
lightning.  They have just simulated the conductive properties by
subjecting their coatings to 100KV arc from Tesla coils.  Not a
true test of a a high voltage gas plasma conductive path.  Check
the fine print/ warranty from these firms.

They did do some research on lighning preventers and
debunked the notion of bristle/ brush aerials as ion emitters for
lightning dissipation.  They get hit as often and and what's worse
is not only do they disintegrate  when struck but they do not
provide a sufficient conduit to ground.  Net result is bristle/ brush
aerials DO NOT protect the surrounding region from direct
impact or side flashes.  In other word you are better off without a
brush aerial.  The tried and tested blunt tip aerials still work the
best.  They may not prevent a strike but when hit they are more
likely to take the current safely to ground.

Otherwise maybe the metal mix epoxy and carbon fiber or metal
mesh surface (painted or course) could be satisfactory.  That's
what the aircraft industy is suggesting.  IN addition with the
advent of weather radars and wind shear information, fewer
lightning impacts are being reported.  Planes are staying away
from problem storms.  Now if boats could do the same ?

Regards,

JT

--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
>
>   You wrote
>   Most of their work has been sponsored by Aeronautical
agencies
>   and power companies.  Looking for damage/ impact to
aircraft/
>   towers, transmission lines, residential structures.  Not sure
they
>   have fried any boats or boat materials.  Interesting research if
not
>   a little dangerous.
>
>   This is interesting because one of the modern materials in
aircraft construction is carbon. The construction methods are
similar to boat methods. They probably have some test data
>   I would be interested in hearing the outcomes if you find any
>   rgs
>   Tony
>
>
> [Non-text portions of this message have been removed]

You wrote
   Most of their work has been sponsored by Aeronautical agencies
   and power companies.  Looking for damage/ impact to aircraft/
   towers, transmission lines, residential structures.  Not sure they
   have fried any boats or boat materials.  Interesting research if not
   a little dangerous.

   This is interesting because one of the modern materials in aircraft
construction is carbon. The construction methods are similar to boat methods.
They probably have some test data
   I would be interested in hearing the outcomes if you find any
   rgs
   Tony


[Non-text portions of this message have been removed]

I saw those docu on "the Discovery Channel"  sending up
rockets with wire leaders to attract lightning.  They have been
doing it for about 10 years.  Didn't see any specific published
articles on propogation through specific materials.  Have to dig
around their website.  The test facility is run by the University of
Florida with grants from many agencies.  They have plenty of
lightning in that vicinity annually so it's a good location.  Not so
good for sailboats.  But that facility is still in operation so will
check to see fi they have done much testing with boats.

Most of their work has been sponsored by Aeronautical agencies
and power companies.  Looking for damage/ impact to aircraft/
towers, transmission lines, residential structures.  Not sure they
have fried any boats or boat materials.  Interesting research if not
a little dangerous.

JT

--- In harryproa@..., "Tony Richardson"
<atrichardson@b...> wrote:
> You wrote
>
>   No one can provide any statistic that lightning rods attract or
>   repel lightning, but there is is plenty of evidence that if struck
the
>   rod will reduce your damage.
>
>   MY reco is is if you sail in the US East Coast, Great Lakes or
>   Gulf, your risk is substantially greater than many other parts of
>   the globe.  Might be prudent.  Since fresh water is is a
>   significantly worse conductor, might be foolish to sail Great
>   Lakes with a carbon spar and no rod.
>
>
>   I went to the USA a few years ago and when there saw a
lightening research center in Florida. It had something to do with
NASA and I watched a doco on their work. They could
consistantly make lightening hit the same point. Maybe they have
some experience with carbon. It may be worth finding out. They
blew up every piece of measuring equipment they tried. I don't
know if it still exists.
>   Rgs
>   Tony
>
>
> [Non-text portions of this message have been removed]

You wrote

   No one can provide any statistic that lightning rods attract or
   repel lightning, but there is is plenty of evidence that if struck the
   rod will reduce your damage.

   MY reco is is if you sail in the US East Coast, Great Lakes or
   Gulf, your risk is substantially greater than many other parts of
   the globe.  Might be prudent.  Since fresh water is is a
   significantly worse conductor, might be foolish to sail Great
   Lakes with a carbon spar and no rod.


   I went to the USA a few years ago and when there saw a lightening research
center in Florida. It had something to do with NASA and I watched a doco on
their work. They could consistantly make lightening hit the same point. Maybe
they have some experience with carbon. It may be worth finding out. They blew up
every piece of measuring equipment they tried. I don't know if it still exists.
   Rgs
   Tony


[Non-text portions of this message have been removed]

It is well known in fishing circles that if you have a carbon fishing rod and a
storm comes about then you should put it away. Many fisherman have been struck,
particularly beach fisherman with long rods.
I think however carbon is technically a resistor. It will conduct but
reluctantly.
It is used in ignition leads for car engines because of this. It provides a
suppressor quality so that the spark doesn't affect your radio reception.
Alloy on the other hand is a well known conductor and as pretty much your only
other alternative. I know which one I would rather have up above me and that's
carbon.
One point that is only my opinion is that an alloy mast may survive a strike
intact providing the fittings are not blown off. I think a carbon mast would be
damaged beyond repair because of its resistance. It would heat up to the point
where the resin would burn and if that happened it would weaken the mast. But I
have no evidence of this as its just a theory.
Rgs
Tony:-)
- Original Message -----
   From: Robert
   To: harryproa@...
   Sent: Tuesday, January 27, 2004 8:35 AM
   Subject: [harryproa] lightning and carbon masts


   The recent thunderstorms and being fairly close to some zapped trees
   got me thinking of how carbon fibre masts with spectra rigging
   perform around lightning. Carbon itself being a good conductor but
   the resin more or less insulating it. I was wondering if some metal
   needed to be used on the boat as a lightning rod.
   Robert



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[Non-text portions of this message have been removed]

Yes you play the odds with this.  Based upon what I have read,
you are correct, the carbon is a good conductor but the layered
effect and the insulating resins cause resistance in a direct hit.
All the experts agree if your carbon mast is hit without an external
ground, you have to throw away the mast. (Assumng it doesn't
explode) .  The resins will vaporize due to resistive heat and all
aboard are at great risk of electrocution from side flashes.

I plan a lightning rod for use in Florida.  It will go through the
mast to a ground plate bottom of the LW hull.  It will have some
issues as the mast rotates to keep direct contact with the thru
bolts to the ground plate.  If you are planning a rod/ wire/ pipe
internally or externally it cannot have direct contact with the
carbon mast.  As noted if the lightning current gets into the
carbon it will use it as another path to ground, ruining the mast.
Your grounding system should be insulated from the carbon
material.

No one can provide any statistic that lightning rods attract or
repel lightning, but there is is plenty of evidence that if struck the
rod will reduce your damage.

MY reco is is if you sail in the US East Coast, Great Lakes or
Gulf, your risk is substantially greater than many other parts of
the globe.  Might be prudent.  Since fresh water is is a
significantly worse conductor, might be foolish to sail Great
Lakes with a carbon spar and no rod.

Regards,

JT

--- In harryproa@..., "Robert"
<cateran1949@y...> wrote:
>  The recent thunderstorms and being fairly close to some
zapped trees
> got me thinking of how carbon fibre masts with spectra rigging
> perform around lightning. Carbon itself being a good conductor
but
> the resin more or less insulating it. I was wondering if some
metal
> needed to be used on the boat as a lightning rod.
> Robert

The recent thunderstorms and being fairly close to some zapped trees
got me thinking of how carbon fibre masts with spectra rigging
perform around lightning. Carbon itself being a good conductor but
the resin more or less insulating it. I was wondering if some metal
needed to be used on the boat as a lightning rod.
Robert