In another thread some mentioned lightning protection. There seem to
b e several schools of thought on the topic ranging from preventing a
strike to dissipating it when it happens. I really do not think there
is much you can do to prevent a strike on a sailboat except to be in
proximity to other tall objects. When you consider the voltages
involved, everything becomes a conductor which is why a tall tree gets
hit as often as a tower of the same height. I also do not think that
lightning dissipators work. In fact, they may make you more
susceptible to a strike by increasing the E field in its vicinity.
Given that the water is so murky on the subject of protection,, I
favor getting rid of it after a strike and attaching a small conductor
to your hull isnt the best way. You may end up with a hole in your
hull. Instead, I have a 2'X2' copper plate soldered and bolted to 00
gage tinned battery cable 20' long with an eyelet on the other end.
When in a storm, I throw the plate over the side and attach the eyelet
to the mast up high so as to minimize bends in the cable. I want to
have the current go through the cable while having the shrouds help
protect us inside them.
I once did a calculation on the probability of a lone sailboat getting
hit if out in a storm and came up with a number that seemed too high
yet when compared with insurance statistics turned out to be
reasonable. Basically, you should avoid being the only tall thing
under such a storm. Being one of many tall things is ok

wrote in message
...


I am always curious about how a boat takes a hit but I do have some
experience with a lightning rod. I put a 3' copper rod over my weather
station with a pointy stainless steel tip, connected to 2ga copper
wire and terminated in a ground rod (connected to my extensive house
grounding system)
It has been hit twice that I know of and I was about 30' away during
one of them. A mexican laborer was pretty much under it, plastered
against my garage door. Other than the poop reflex we were totally
unaffected.. The steel garage door he was plastered to is bonded to
the same grounding system as the lightning rod as is the wet concrete
driveway I was standing on.
We were fine. The weather station ... not so much ... either time.


Our house has a copper clad cupula, grounded to two metal rods located near
the house power panels.
It's been hit at least three times. Once, the driveway (near the metal
rods) snapped, crackled and popped for about 5 seconds following the hit as
the energy was absorbed by the ground plane. Originally, it also had a big,
copper weather vane. That has long since been vaporized.

Fine for a house .... not so fine for a boat.

Eisboch

On Wed, 20 Aug 2008 19:38:50 -0400, "Eisboch"
wrote:


wrote in message
.. .


I am always curious about how a boat takes a hit but I do have some
experience with a lightning rod. I put a 3' copper rod over my weather
station with a pointy stainless steel tip, connected to 2ga copper
wire and terminated in a ground rod (connected to my extensive house
grounding system)
It has been hit twice that I know of and I was about 30' away during
one of them. A mexican laborer was pretty much under it, plastered
against my garage door. Other than the poop reflex we were totally
unaffected.. The steel garage door he was plastered to is bonded to
the same grounding system as the lightning rod as is the wet concrete
driveway I was standing on.
We were fine. The weather station ... not so much ... either time.


Our house has a copper clad cupula, grounded to two metal rods located near
the house power panels.
It's been hit at least three times. Once, the driveway (near the metal
rods) snapped, crackled and popped for about 5 seconds following the hit as
the energy was absorbed by the ground plane. Originally, it also had a big,
copper weather vane. That has long since been vaporized.

Fine for a house .... not so fine for a boat.

Eisboch

This is the best thing I've seen on lightning, and think it pretty
well hits the mark on what you can do on a boat.
It's geared toward sailboats, but the principles are there.
For electronics gear, I would do the same as I do at home with my
computer and other electronic gear if I anticipate lightning:
unplug it. An insulated non-conducting case might be appropriate
for a radio when at sea.
http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

--Vic

On Aug 20, 7:57 pm, Vic Smith wrote:
On Wed, 20 Aug 2008 19:38:50 -0400, "Eisboch"
wrote:





wrote in message
.. .

I am always curious about how a boat takes a hit but I do have some
experience with a lightning rod. I put a 3' copper rod over my weather
station with a pointy stainless steel tip, connected to 2ga copper
wire and terminated in a ground rod (connected to my extensive house
grounding system)
It has been hit twice that I know of and I was about 30' away during
one of them. A mexican laborer was pretty much under it, plastered
against my garage door. Other than the poop reflex we were totally
unaffected.. The steel garage door he was plastered to is bonded to
the same grounding system as the lightning rod as is the wet concrete
driveway I was standing on.
We were fine. The weather station ... not so much ... either time.

Our house has a copper clad cupula, grounded to two metal rods located near
the house power panels.
It's been hit at least three times. Once, the driveway (near the metal
rods) snapped, crackled and popped for about 5 seconds following the hit as
the energy was absorbed by the ground plane. Originally, it also had a big,
copper weather vane. That has long since been vaporized.

Fine for a house .... not so fine for a boat.

Eisboch

This is the best thing I've seen on lightning, and think it pretty
well hits the mark on what you can do on a boat.
It's geared toward sailboats, but the principles are there.
For electronics gear, I would do the same as I do at home with my
computer and other electronic gear if I anticipate lightning:
unplug it. An insulated non-conducting case might be appropriate
for a radio when at sea.http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

--Vic

That is a good article.

Thanks

wrote in message
...

On Aug 20, 7:57 pm, Vic Smith wrote:


This is the best thing I've seen on lightning, and think it pretty
well hits the mark on what you can do on a boat.
It's geared toward sailboats, but the principles are there.
For electronics gear, I would do the same as I do at home with my
computer and other electronic gear if I anticipate lightning:
unplug it. An insulated non-conducting case might be appropriate
for a radio when at sea.http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

--Vic

That is a good article.

Thanks


It is a good article in terms of what happens when you get hit and how to
design for a hit.

The other school of thought is a design to minimize your chances of getting
hit in the first place.

Both approaches are not fool proof, as the effects of a hit are not 100%
predictable, nor is a system designed to minimize the chances of a hit 100%
effective.

Personally, having many years of experience in designing vacuum processing
equipment that contain controlled plasma discharges, (basically the same as
lightning, except it is a sustained and controlled electrical discharge
through ionized gas), I am more of a believer in the concept of minimizing
the conditions that would lead to a strike in the first place. Ironically,
the approach is almost the opposite of trying to design a system to capture
the energy of a strike and safely transfer it to ground.

Eisboch

On Wed, 20 Aug 2008 23:09:52 -0400, "Eisboch"
wrote:


wrote in message
...

On Aug 20, 7:57 pm, Vic Smith wrote:


This is the best thing I've seen on lightning, and think it pretty
well hits the mark on what you can do on a boat.
It's geared toward sailboats, but the principles are there.
For electronics gear, I would do the same as I do at home with my
computer and other electronic gear if I anticipate lightning:
unplug it. An insulated non-conducting case might be appropriate
for a radio when at sea.http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

--Vic

That is a good article.

Thanks


It is a good article in terms of what happens when you get hit and how to
design for a hit.

The other school of thought is a design to minimize your chances of getting
hit in the first place.

Both approaches are not fool proof, as the effects of a hit are not 100%
predictable, nor is a system designed to minimize the chances of a hit 100%
effective.

Personally, having many years of experience in designing vacuum processing
equipment that contain controlled plasma discharges, (basically the same as
lightning, except it is a sustained and controlled electrical discharge
through ionized gas), I am more of a believer in the concept of minimizing
the conditions that would lead to a strike in the first place. Ironically,
the approach is almost the opposite of trying to design a system to capture
the energy of a strike and safely transfer it to ground.

Biggest trouble with avoidance is that any boat is the tallest thing
around, and will attract any lightning that would have struck anywhere
near there without it. You get a choice of the mast or the lightning
rod. No strikes on boats just isn't doable. They even put masts on
powerboats to get the radar and VHF antennae higher for more range.
The only counter measure that really works is radar and a very big
engine.
Hiding under a bridge works, if there is room. A powerboat in a marina
next to sailboats won't be hit. Someone checked statistics on one make
and model of powerboat and found that more than ten percent had been
hit in the last five years.

Casady

On Aug 21, 1:47 am, (Richard Casady)
wrote:
On Wed, 20 Aug 2008 23:09:52 -0400, "Eisboch"
wrote:





wrote in message
...

On Aug 20, 7:57 pm, Vic Smith wrote:

This is the best thing I've seen on lightning, and think it pretty
well hits the mark on what you can do on a boat.
It's geared toward sailboats, but the principles are there.
For electronics gear, I would do the same as I do at home with my
computer and other electronic gear if I anticipate lightning:
unplug it. An insulated non-conducting case might be appropriate
for a radio when at sea.http://edis.ifas.ufl.edu/pdffiles/SG/SG07100.pdf

--Vic

That is a good article.

Thanks

It is a good article in terms of what happens when you get hit and how to
design for a hit.

The other school of thought is a design to minimize your chances of getting
hit in the first place.

Both approaches are not fool proof, as the effects of a hit are not 100%
predictable, nor is a system designed to minimize the chances of a hit 100%
effective.

Personally, having many years of experience in designing vacuum processing
equipment that contain controlled plasma discharges, (basically the same as
lightning, except it is a sustained and controlled electrical discharge
through ionized gas), I am more of a believer in the concept of minimizing
the conditions that would lead to a strike in the first place. Ironically,
the approach is almost the opposite of trying to design a system to capture
the energy of a strike and safely transfer it to ground.

Biggest trouble with avoidance is that any boat is the tallest thing
around, and will attract any lightning that would have struck anywhere
near there without it. You get a choice of the mast or the lightning
rod. No strikes on boats just isn't doable. They even put masts on
powerboats to get the radar and VHF antennae higher for more range.
The only counter measure that really works is radar and a very big
engine.
Hiding under a bridge works, if there is room. A powerboat in a marina
next to sailboats won't be hit. Someone checked statistics on one make
and model of powerboat and found that more than ten percent had been
hit in the last five years.

Casady

Eisboch:

C'mon down and you can help build a big sputtering system for us.

wrote in message
...


Eisboch:

C'mon down and you can help build a big sputtering system for us.


It's funny. The bulk of the systems we designed and built were conventional
batch type box coaters for optics, utilizing thermal and electron beam
evaporation, often with an ion source for controlling the packing density.
Mostly for high energy laser stuff, but we also built several systems over
the years for ophthalmic coatings. "Neutral Green" :-)

We also built many sputter deposition systems for everything from optics,
diamond-like coatings, to razor blades.
Plasma processing systems was my personal favorite and interest. It
combines so many technical disciplines that it was never boring.

Eisboch

On Aug 21, 9:01 am, "Eisboch" wrote:
wrote in message

...



Eisboch:

C'mon down and you can help build a big sputtering system for us.

It's funny. The bulk of the systems we designed and built were conventional
batch type box coaters for optics, utilizing thermal and electron beam
evaporation, often with an ion source for controlling the packing density.
Mostly for high energy laser stuff, but we also built several systems over
the years for ophthalmic coatings. "Neutral Green" :-)

We also built many sputter deposition systems for everything from optics,
diamond-like coatings, to razor blades.
Plasma processing systems was my personal favorite and interest. It
combines so many technical disciplines that it was never boring.

Eisboch

We need to make a sputter system to deposit thin multilayers on small
diameter parabolic mandrels. The mandrels are highly polished and we
need coatings with surface and interfacial roughness of less than 10
angstroms. These are for x-ray mirrors. See our web site at
www.parallax-x-ray.com

On Wed, 20 Aug 2008 19:38:50 -0400, "Eisboch"
wrote:


wrote in message
.. .


I am always curious about how a boat takes a hit but I do have some
experience with a lightning rod. I put a 3' copper rod over my weather
station with a pointy stainless steel tip, connected to 2ga copper
wire and terminated in a ground rod (connected to my extensive house
grounding system)
It has been hit twice that I know of and I was about 30' away during
one of them. A mexican laborer was pretty much under it, plastered
against my garage door. Other than the poop reflex we were totally
unaffected.. The steel garage door he was plastered to is bonded to
the same grounding system as the lightning rod as is the wet concrete
driveway I was standing on.
We were fine. The weather station ... not so much ... either time.


Our house has a copper clad cupula, grounded to two metal rods located near
the house power panels.
It's been hit at least three times. Once, the driveway (near the metal
rods) snapped, crackled and popped for about 5 seconds following the hit as
the energy was absorbed by the ground plane. Originally, it also had a big,
copper weather vane. That has long since been vaporized.

Fine for a house .... not so fine for a boat.

You evidently think a lightning rod will somehow increase the danger,
but such has been proven by long experience not to be the case. BS in
other words. The lightning rod doesn't know or care what is under it.
It prevents strikes in a 90 degree cone under it. Works equally well
for buildings, boats, and powerlines.

Casady