On Nov 12, 7:57*pm, Jere Lull wrote:
My evidence is anecdotal only, primary one was one boat getting a
bottle brush installed by the factory team.

Lightning rods don't attract lightning. Lightnng will strike
because electrical charges must be connected from the cloud to ground.
Something will attract or will prevent lightning is often myth because
many know only from observation rahter than first learn the basic
technology. Observation without fundamental knonwledge is also called
junk science reasoning.

Required is little to connect ligthning harmlessly to earth. Ben
Franklin demonstrated the concept in 1752 to halt damage to churches.
The term 'little' is subjective. But if one does not first learn the
basics, then 'little' becomes 'massive'.

A U of FL article cited by Roger Long provides fundamental
information. Lightning may even strike a valley rather than nearby
hills. Why? Where are those charges that lightning must connect to?
Using only observation, then clearly lightning seeks the lowest
point. First learn the science to understand why lightning strikes a
valley or a nearby mountain, or why the best place to strike was that
one boat.

The anecdotal evidence is flawed because its conclusoin is based on
an observation without comprehensive study of what connected to that
boat, the content of soil beneath that boat, where the boat was
located in relation to earthed charges, etc.

On Wed, 12 Nov 2008 17:20:21 -0800 (PST), wrote:

The anecdotal evidence is flawed because its conclusoin is based on
an observation without comprehensive study of what connected to that
boat, the content of soil beneath that boat, where the boat was
located in relation to earthed charges, etc.

OK, let me ask you this: 300 miles offshore in more than 5,000 feet
of salt water, lightning decides to strike a nearby wave top instead
of the well grounded 80 ft mast of an all aluminum boat.

Why?

Wayne.B wrote:

On Wed, 12 Nov 2008 17:20:21 -0800 (PST), wrote:


The anecdotal evidence is flawed because its conclusoin is based on
an observation without comprehensive study of what connected to that
boat, the content of soil beneath that boat, where the boat was
located in relation to earthed charges, etc.


OK, let me ask you this: 300 miles offshore in more than 5,000 feet
of salt water, lightning decides to strike a nearby wave top instead
of the well grounded 80 ft mast of an all aluminum boat.

Why?

Butterflies Wings or in this case, probably dust particles or rain
drops. The initial ionisation of the air immediatly below the leader of
the stroke is dependent on field strength but field strength in most
stuations falls off with the square of the distance so a rain drop of
lets say 3 mm diameter a meter from the tip of the leader has more
influence than that mast 100 metres away.

Its only if you have sharp enough edges and enough field strength to get
local ionisation on the rigging, St Elmo's fire being the extreme
example, that the difference between an 80 ft mast and a 8 ft wave
becomes significant. Waves dont have sharp edges . . .

--
Ian Malcolm. London, ENGLAND. (NEWSGROUP REPLY PREFERRED)
ianm[at]the[dash]malcolms[dot]freeserve[dot]co[dot]uk
[at]=@, [dash]=- & [dot]=. *Warning* HTML & 32K emails -- NUL:
'Stingo' Albacore #1554 - 15' Early 60's, Uffa Fox designed,
All varnished hot moulded wooden racing dinghy.

"Jere Lull" wrote in message
news:2008111219570616807-jerelull@maccom...
On 2008-11-12 05:25:05 -0500, "Roger Long" said:

Jere Lull wrote:

But there are funner things to do since it seems the commercial products
seem to attract strikes.

I don't see a shred of evidence to support this. I think it more likely
that people who are on the water enough in frequent strike zones to be at
high risk install protection and therefore get struck more often simply
because they are at higher risk.

My evidence is anecdotal only, primary one was one boat getting a bottle
brush installed by the factory team. Though the boat's mast was relatively
short compared to dozens of boats around it, it was the only one hit -- a
couple of weeks later. The device's insurance ensured they paid nothing to
get everything fixed, but they weren't able to get enough of the systems
up to use the boat that season.

Even land-based lightning rods have to be very carefully installed or they
attract strikes. (that's something I read in school, perhaps connected to
Ben Franklin.)


This is the first time anyone has mentioned the 'bottle brush' but I have
always believed that a spiky device at the very top of the lightning rod is
essntial if it is to act effectively to reduce the possibility of a
dangerous strike.
My understanding is that in the moments before a strike the 'positive'
charge in the clouds draws up a negative charge through the lightning rod.
This, in itself, increases the likelihood of a strike onto the mast, but if
you have sharp points at the top of the lightning rod these concentrate the
local negative charge so much that the positive force in the cloud is
dissipated to earth down your lightning rod before it can build to a high
enough potential in the local clouds to break through the atmosphere as a
full lightning strike.
If I am right on this, and I would welcome anyone who can comment on this
theory, then there are two ways to go, either have a proper lightning rod
with sharp spikes on it, or do not have an earthed lightning rod at all.
In a previous post I told how I was caught out in open water during a
lightning storm and yet my metal mast, which was not earthed, was not struck
even though strikes were going into the sea all around me.

I saw something in some science news on the net shortly before I started
getting interested in this subject, I'll have to find it again but the gist
from a quick skim was that some scientists now believe that ground strikes
are following an ionization channel opened up one of the high energy cosmic
rays that are constantly bombarding the earth. The strike may divert to a
high object near the ground but the ray path could also lead it to the water
or a lower object.

--
Roger Long

On Wed, 12 Nov 2008 17:20:21 -0800 (PST), wrote:

On Nov 12, 7:57*pm, Jere Lull wrote:
My evidence is anecdotal only, primary one was one boat getting a
bottle brush installed by the factory team.

Lightning rods don't attract lightning. Lightnng will strike
because electrical charges must be connected from the cloud to ground.
Something will attract or will prevent lightning is often myth because
many know only from observation rahter than first learn the basic
technology. Observation without fundamental knonwledge is also called
junk science reasoning.

Required is little to connect ligthning harmlessly to earth. Ben
Franklin demonstrated the concept in 1752 to halt damage to churches.
The term 'little' is subjective. But if one does not first learn the
basics, then 'little' becomes 'massive'.

A U of FL article cited by Roger Long provides fundamental
information. Lightning may even strike a valley rather than nearby
hills. Why? Where are those charges that lightning must connect to?
Using only observation, then clearly lightning seeks the lowest
point. First learn the science to understand why lightning strikes a
valley or a nearby mountain, or why the best place to strike was that
one boat.

The anecdotal evidence is flawed because its conclusoin is based on
an observation without comprehensive study of what connected to that
boat, the content of soil beneath that boat, where the boat was
located in relation to earthed charges, etc.

Oh no! It's W_Tom. Well known and very tired usenet lightning nutball,
postng with a new nickname. He automatuicaly scours usenet for any
posts that mention lightning or power surges, and he jumps in with his
absurd diatribes. This fairly calm sounding post by him is just the
introductory prelude. Poke him, or disagree, and then the fun begins.

On Thu, 13 Nov 2008 05:25:43 -0500, "Roger Long"
wrote:

I saw something in some science news on the net shortly before I started
getting interested in this subject, I'll have to find it again but the gist
from a quick skim was that some scientists now believe that ground strikes
are following an ionization channel opened up one of the high energy cosmic
rays that are constantly bombarding the earth. The strike may divert to a
high object near the ground but the ray path could also lead it to the water
or a lower object.


Great. Now it's all very clear.

--Vic

On 2008-11-13 03:40:42 -0500, "Edgar" said:

This is the first time anyone has mentioned the 'bottle brush' but I have
always believed that a spiky device at the very top of the lightning rod is
essntial if it is to act effectively to reduce the possibility of a
dangerous strike.

That is one theory, the use of a "bottle brush" conductor is another;
there are others. Knowing a bit about electrical engineering,
electricity and electronics, I can follow the observations and math and
find good points in many of the theories advanced.

The problem is that no matter how long scientists (and snake-oil
salesmen) have been studying the problem, lightning strikes are
relatively random (determined by cosmic rays?) with the probability of
a strike in a particular location only slightly affected by man-made
agents.

There *are* well-documented things to do (or not) before you get hit:
Do not ground to your through hulls, ground to something big,
preferably without vulnerable hull between, try to "persuade" the
lightning to stay outside of the boat's interior, put sensitive
electronics in a Faraday cage, add bonding to fixed equipment separate
from grounding....

Personally, the best way to avoid lightning is to be elsewhere. Given
unlimited money, we'd have a metal hull. Given reality, my efforts go
first to damage-control, then relaxing about those things I can't
control.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/

On 2008-11-13 13:17:26 -0500, said:

I've heard of many folks putting sensitive gear inside the metal oven
for protrection. I have no idea how effective it is, but I doubt it
makes things worse.

That works about as well as anything. If I ever get spare handheld
electronics, I'll store them in metal "ammo" cases. There's always a
chance that a sufficiently-large strike will punch a hole through, but
I believe I'll have more major problems to deal with in that case.

--
Jere Lull
Xan-à-Deux -- Tanzer 28 #4 out of Tolchester, MD
Xan's pages: http://web.mac.com/jerelull/iWeb/Xan/
Our BVI trips & tips: http://homepage.mac.com/jerelull/BVI/

In article , Vic Smith wrote:
On Thu, 13 Nov 2008 05:25:43 -0500, "Roger Long"
wrote:

I saw something in some science news on the net shortly before I started
getting interested in this subject, I'll have to find it again but the gist
from a quick skim was that some scientists now believe that ground strikes
are following an ionization channel opened up one of the high energy cosmic
rays that are constantly bombarding the earth. The strike may divert to a
high object near the ground but the ray path could also lead it to the water
or a lower object.


Great. Now it's all very clear.

VBG Oh yes, that made me laugh. TY.

Justin.

--
Justin C, by the sea.