"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.