LIGHTNING STRIKE PROBABILITY
 

Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

Assume LONE sailboat, Flat conducting ocean, assume the mast is well
grounded, assume lightning equally distributed over the thunderstorm
area.

Now, I have forgotten how to do this calculation (this used to be my
speciality) but I vaguely remember that a spike type conductor above a
grounded plane produces minimal effects more than 3X its length away.
This means that a mast produces an EFFECTIVE AREA (a) of pi*9*l^2
where l = mast length.

BTW, I work in meters.


I assume a thunderstorm diameter of 4 km based on driving through one
two days ago for a total storm area of 12X10^6 m^2. I assume the
lightning strike rate is about 3/minute and the storm lasts for 40
minutes for a total number of strikes/storm (n) to be 120.

SO...the probability of getting hit is: P=n*a/A *L (L is your "luck
factor", 0L1 means you are either optimistic or lucky, L=1 means you
do not believe in Luck, L1 means you are pessimistic or unlucky, L=0
means you dont really sail). Top of my mast is 17 m above water for
an effective area of 7803 m^2.

So, P= 120*7803/16X10^6 *(L) = 585225X10^-6 * (L)= .058 * (L) or 5.8%
* (L).

Based on limited experience with games of chance, I estimate my L = 3
so my strike probability is 17.4%.

Seriously, the 5.8% chance shows why sailboats do not get struck more
often although they are the tallest things around.

LIGHTNING STRIKE PROBABILITY
 

they don't begin to get struck 1 time in 20 storms. not even close.

Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

Assume LONE sailboat, Flat conducting ocean, assume the mast is well
grounded, assume lightning equally distributed over the thunderstorm
area.

Now, I have forgotten how to do this calculation (this used to be my
speciality) but I vaguely remember that a spike type conductor above a
grounded plane produces minimal effects more than 3X its length away.
This means that a mast produces an EFFECTIVE AREA (a) of pi*9*l^2
where l = mast length.

BTW, I work in meters.


I assume a thunderstorm diameter of 4 km based on driving through one
two days ago for a total storm area of 12X10^6 m^2. I assume the
lightning strike rate is about 3/minute and the storm lasts for 40
minutes for a total number of strikes/storm (n) to be 120.

SO...the probability of getting hit is: P=n*a/A *L (L is your "luck
factor", 0L1 means you are either optimistic or lucky, L=1 means you
do not believe in Luck, L1 means you are pessimistic or unlucky, L=0
means you dont really sail). Top of my mast is 17 m above water for
an effective area of 7803 m^2.

So, P= 120*7803/16X10^6 *(L) = 585225X10^-6 * (L)= .058 * (L) or 5.8%
* (L).

Based on limited experience with games of chance, I estimate my L = 3
so my strike probability is 17.4%.

Seriously, the 5.8% chance shows why sailboats do not get struck more
often although they are the tallest things around.

I would have to give up sailing
 

if I thought I had a 5% chance (1 in 20) of any given storm hitting
me!!! OUCH, Paul


Seriously, the 5.8% chance shows why sailboats do not get struck more
often although they are the tallest things around.

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

dum dum, a 1 chance in 20 means a long oak tree standing on a hill, or a
telephone pole on the roadway would be splintered to toothpicks in a couple
seasons.

they don't begin to get struck 1 time in 20 storms. not even close.

Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

Assume LONE sailboat, Flat conducting ocean, assume the mast is well
grounded, assume lightning equally distributed over the thunderstorm
area.

Now, I have forgotten how to do this calculation (this used to be my
speciality) but I vaguely remember that a spike type conductor above a
grounded plane produces minimal effects more than 3X its length away.
This means that a mast produces an EFFECTIVE AREA (a) of pi*9*l^2
where l = mast length.

BTW, I work in meters.


As I write, a weak thunderstorm is passing over the bldg. lightning
rate seems low, less than once/minute and most are prob NOT cloud to
ground. However, I estimate wind at 40 kts.

Based on a few storms I have seen on Apalachee bay, I think the 5.8%
probability for those intense storms to be reasonable and I seriously
avoid them.

Strongest storms cover a larger area with greater wind. I have never
been in one of those but have watched them. The sky doesnt just get
dark, but turns a strange color. Intense strike rate for a few
minutes followed by a sudden increase in rain rate followed by a taper
off in wind and strike rate.

I assume a thunderstorm diameter of 4 km based on driving through one
two days ago for a total storm area of 12X10^6 m^2. I assume the
lightning strike rate is about 3/minute and the storm lasts for 40
minutes for a total number of strikes/storm (n) to be 120.

SO...the probability of getting hit is: P=n*a/A *L (L is your "luck
factor", 0L1 means you are either optimistic or lucky, L=1 means you
do not believe in Luck, L1 means you are pessimistic or unlucky, L=0
means you dont really sail). Top of my mast is 17 m above water for
an effective area of 7803 m^2.

So, P= 120*7803/16X10^6 *(L) = 585225X10^-6 * (L)= .058 * (L) or 5.8%
* (L).

Based on limited experience with games of chance, I estimate my L = 3
so my strike probability is 17.4%.

Seriously, the 5.8% chance shows why sailboats do not get struck more
often although they are the tallest things around.

LIGHTNING STRIKE PROBABILITY
 

How do you define "effective" area?
Your equation assumes that any lightning within the effective area of your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

....

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

parray, you take back everything you ever said about anything.

Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

Assume LONE sailboat, Flat conducting ocean, assume the mast is well
grounded, assume lightning equally distributed over the thunderstorm
area.

Now, I have forgotten how to do this calculation (this used to be my
speciality) but I vaguely remember that a spike type conductor above a
grounded plane produces minimal effects more than 3X its length away.
This means that a mast produces an EFFECTIVE AREA (a) of pi*9*l^2
where l = mast length.

BTW, I work in meters.


As I write, a weak thunderstorm is passing over the bldg. lightning
rate seems low, less than once/minute and most are prob NOT cloud to
ground. However, I estimate wind at 40 kts.

Based on a few storms I have seen on Apalachee bay, I think the 5.8%
probability for those intense storms to be reasonable and I seriously
avoid them.

Strongest storms cover a larger area with greater wind. I have never
been in one of those but have watched them. The sky doesnt just get
dark, but turns a strange color. Intense strike rate for a few
minutes followed by a sudden increase in rain rate followed by a taper
off in wind and strike rate.

I assume a thunderstorm diameter of 4 km based on driving through one
two days ago for a total storm area of 12X10^6 m^2. I assume the
lightning strike rate is about 3/minute and the storm lasts for 40
minutes for a total number of strikes/storm (n) to be 120.

SO...the probability of getting hit is: P=n*a/A *L (L is your "luck
factor", 0L1 means you are either optimistic or lucky, L=1 means you
do not believe in Luck, L1 means you are pessimistic or unlucky, L=0
means you dont really sail). Top of my mast is 17 m above water for
an effective area of 7803 m^2.

So, P= 120*7803/16X10^6 *(L) = 585225X10^-6 * (L)= .058 * (L) or 5.8%
* (L).

Based on limited experience with games of chance, I estimate my L = 3
so my strike probability is 17.4%.

Seriously, the 5.8% chance shows why sailboats do not get struck more
often although they are the tallest things around.








OK, OK, I take back anything I said about wimpy thunderstorms up north
after viewing a series of websites with supercell storms over the
great plains states and all the way up to MN.

LIGHTNING STRIKE PROBABILITY
 

"rnh17" wrote in message ...
How do you define "effective" area?
Your equation assumes that any lightning within the effective area of your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...


As I said, effective area is defined as pi*9*(mast height squared).
This is comes from the distance over which a conductor over a flat
conducting plane (3* mast height) has minimal effect on the electric
field distribution(you know, the area of a circle being pies are
squared.

Telephone poles have conductors attached to them and normally have a
ground wire. Trees on the top of a tall hill all alone would not last
long if active thunderstorms passed over them often enough. Around
here, tall pines get hit and die while many other trees survive
strikes. Look at pines with vertical slashes on them running waaaay
up the tree, this is often caused by lightning strikes.

If you do not believe my 1 in 20 chance, consider the number of
golfers who get hit each year here in FL playing during thunderstorms.
Furthermore, find something wrong with my reasoning. Since the math
is correct, the only possibility is that the cloud to ground strike
rate is too high but I watched such strikes during a storm to get this
rate.

I believe my analysis is correct, and until I did this simple
calculation based on area, my experience with electrostatics had
caused me to think the probability should be MUCH higher with this set
of assumptions.

LIGHTNING STRIKE PROBABILITY
 

pair of lox, weren't you the guy who claimed expertise in all things because
you have an EE degree in physics?

Yup, that was you.

(Parallax)
Date: 7/10/2004 12:16 PM Eastern Standard Time
Message-id:

"rnh17" wrote in message
...
How do you define "effective" area?
Your equation assumes that any lightning within the effective area of your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...


As I said, effective area is defined as pi*9*(mast height squared).
This is comes from the distance over which a conductor over a flat
conducting plane (3* mast height) has minimal effect on the electric
field distribution(you know, the area of a circle being pies are
squared.

Telephone poles have conductors attached to them and normally have a
ground wire. Trees on the top of a tall hill all alone would not last
long if active thunderstorms passed over them often enough. Around
here, tall pines get hit and die while many other trees survive
strikes. Look at pines with vertical slashes on them running waaaay
up the tree, this is often caused by lightning strikes.

If you do not believe my 1 in 20 chance, consider the number of
golfers who get hit each year here in FL playing during thunderstorms.
Furthermore, find something wrong with my reasoning. Since the math
is correct, the only possibility is that the cloud to ground strike
rate is too high but I watched such strikes during a storm to get this
rate.

I believe my analysis is correct, and until I did this simple
calculation based on area, my experience with electrostatics had
caused me to think the probability should be MUCH higher with this set
of assumptions.

LIGHTNING STRIKE PROBABILITY
 

"rnh17" wrote in message ...
How do you define "effective" area?
Your equation assumes that any lightning within the effective area of your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...

I found a web site that gave a strike rate of about .5 strikes/km^2/yr
but they did not say where they measured this. However, this means
that a lone sailboat with a mast 17 m tall would have a .35% chance
each yr of getting struck. This is an ideal situation though and may
not address the situation of a sailboat under a thunderstorm where the
strike rate/km^2 is hundreds of times higher. Because I know that the
strike rate in Fl is much higher than average, I'd want to double the
strike rate they give to be about 1/km^2/yr. This gives about a .7%
chance each yr of getting hit. Again, this does NOT address the
situation where you know the strike rate is much higer than average
(sitting under a storm). Based on math and observed strike rate, I
still think my estimate is good.

LIGHTNING STRIKE PROBABILITY
 

On 9 Jul 2004 10:29:26 -0700, (Parallax) wrote:

Strongest storms cover a larger area with greater wind. I have never
been in one of those but have watched them. The sky doesnt just get
dark, but turns a strange color. Intense strike rate for a few
minutes followed by a sudden increase in rain rate followed by a taper
off in wind and strike rate.

Parallax, of course you get the worst storms in Florida, but don't
think they don't happen elsewhere anywhere in N. America it gets warm
and humid.

We had tornados in northern Alberta a couple of days ago, and it's not
summer here in Toronto if there isn't a few monster squalls and/or
heat-driven thunderstorms that can spawn waterspouts and plenty of
lightning...

Thankfully, we don't have the duration or the frequency of Florida,
but short of hurricanes, the storms we get CAN be as violent.

BTW, that "strange colour" reference I recognize: it's the hallmark of
a vicious blow. First comes grey, greyer, greyest...then comes a sort
of gangrenous green flecked with black...THAT's the time to duck and
cover/deploy the storm jib/lash down everything! G

R.

LIGHTNING STRIKE PROBABILITY
 

pair of lox, a 5% chance of getting hit = a 95% of NOT getting hit.

A 5% chance of getting hit = .95 times .95 = a 90% of NOT getting hit even
once EITHER time in two tries.

a 5% chance of gettting hit = .95 times .95 times .95 times .95 = 81% of NOT
getting hit even once in FOUR tries.

by 8 tries the chance of NOT getting hit is only about 2 out of 3, by 14 tries
there is a better than even chance of being hit **AT LEAST ONCE**. by 30
tries, the chances of being hit at least once are 4 out of 5. by 50 tries,
chances of being hit at least once are greater than 15 out of 16. by 70 tries,
32 out of 33. by 90 tries, greater than 99 out of a 100.

that oak tree standing on the hill would be toothpicks by the end of the second
season.

Understand that in central Florida they receive more than 100 electrical storms
each year. a 5% chance of getting struck would mean central Florida has never
had trees.



How do you define "effective" area?
Your equation assumes that any lightning within the effective area of your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...

I found a web site that gave a strike rate of about .5 strikes/km^2/yr
but they did not say where they measured this. However, this means
that a lone sailboat with a mast 17 m tall would have a .35% chance
each yr of getting struck. This is an ideal situation though and may
not address the situation of a sailboat under a thunderstorm where the
strike rate/km^2 is hundreds of times higher. Because I know that the
strike rate in Fl is much higher than average, I'd want to double the
strike rate they give to be about 1/km^2/yr. This gives about a .7%
chance each yr of getting hit. Again, this does NOT address the
situation where you know the strike rate is much higer than average
(sitting under a storm). Based on math and observed strike rate, I
still think my estimate is good.

LIGHTNING STRIKE PROBABILITY
 

"Parallax" wrote in message
om...
"rnh17" wrote in message
...
How do you define "effective" area?
Your equation assumes that any lightning within the effective area of
your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...


As I said, effective area is defined as pi*9*(mast height squared).
This is comes from the distance over which a conductor over a flat
conducting plane (3* mast height) has minimal effect on the electric
field distribution(you know, the area of a circle being pies are
squared.

Do you have any equations for chance of getting bitten by a shark? But
seriously, I have no idea what you mean by "the distance...minimal effect on
the field distribution," but for the layman, why do you equate this with
lightning striking in that area?

LIGHTNING STRIKE PROBABILITY
 

But
seriously, I have no idea what you mean by "the distance...minimal effect on
the field distribution,"

no one else has any idea either.

for the layman, why do you equate this with
lightning striking in that area?

because pair of lox has an EE degree in physics. just ask him.

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

yup, pair of lox, there ain't no trees in central Florida, and none either in
Malaysia or Equatorial Africa. All blasted to toothpicks by lightning hundreds
of thousands of years ago.

I am pleased to see that JAX can multiply. However, my analysis
assumes a LONE sailboat (or other tall object).

Now, I found a site giving the strike rate for Malaysia and remember
that only two places have a higher strike rate than Central FL,
Equatorial Africa and SE Asia. Malaysia has a strike rate of
25/km^2/yr. I remember that C. FL rate isnt too much smaller than the
highest so I assume 10/km^2/yr and you get (using my effective area)
of a 7% chance/yr of a LONE sailboat getting hit. I find this to be
VERY believable based on experience.

JAX, not all lightning strikes kill and not all trees hit are killed,
most are not. Perhaps you just are not familiar with being in a high
lightning environment. Around here, I can go into the woods and find
MANY trees that have been hit by lightning. This is particularly true
of tall cypress trees.
I have found web sites calculating strike probability and they all use
a formula similar to mine where effective area goes as the height
squared. However, none i have found specify the factor by wich to
multiply the height to account for electric field modification, they
just qualitatively say it goes as height squared or use empiracaly
derived effective areas.

I still find my calculation to be very reasonable.

LIGHTNING STRIKE PROBABILITY
 

BE CAREFUL, PAIR OF LOX!!! YOU ARE GOING TO DIE A CRISPY CRITTER!!!!!!!

For further local perspective on the strike rate, consider that in my
own back yard of 1 acre, while I have lived here (15 yrs) three trees
have been hit with two being killed. My well enclosed in a shed was
struck. My neighbors well has been struck three times although it is
below ground. JAX, you just dont know lightning.

LIGHTNING STRIKE PROBABILITY
 

Parallax wrote:
(JAXAshby) wrote in message
...
pair of lox, a 5% chance of getting hit = a 95% of NOT getting hit.
snip
I am pleased to see that JAX can multiply. However, my analysis
assumes a LONE sailboat (or other tall object).

JAX multiplying------ what a horrible thought ;-)

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

pair a lox, wanna tell us again about your EE degree in physics? your estimate
does not match up with the math you use to portray your estimate. fine EE you
are, and in physics yet.

btw, if 4% to 20% of all sailboats mooring in the State of Florida get struck
by lightning each year, no insurance company on the planet would insure any
boat in the State of Florida without a HUGE increase in premium as compared to
the State of Georgia or the State of Alabama or the State of Texas of the State
of ...


The Florida Sea Grant Programs paper "Lightning and Sailboats"
estimates that between 4% and 20% of sailboats moored in FL get struck
each yr. Mooring is very close to the case of being a LONE sailbaot I
describe. This is well in accord with my estimates.

Various web sites show the FL strike desnity being 10-30 strikes/km^2.

A LONE tall tree with 5%/yr chance of being struck could live at least
15 yrs having less than 50% chance of being hit. Note that in Central
Florida, there are few tall hills and fewer with lone tall trees.

My analysis appears to be correct.

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

pair of lox, you are stupid beyond words.

tell us again about your double E in physics.



(Parallax)
Date: 7/11/2004 9:00 PM Eastern Daylight Time
Message-id:

(Parallax) wrote in message
.com...
(JAXAshby) wrote in message
...
pair of lox, a 5% chance of getting hit = a 95% of NOT getting hit.

A 5% chance of getting hit = .95 times .95 = a 90% of NOT getting hit
even
once EITHER time in two tries.

a 5% chance of gettting hit = .95 times .95 times .95 times .95 = 81% of
NOT
getting hit even once in FOUR tries.

by 8 tries the chance of NOT getting hit is only about 2 out of 3, by 14
tries
there is a better than even chance of being hit **AT LEAST ONCE**. by 30
tries, the chances of being hit at least once are 4 out of 5. by 50
tries,
chances of being hit at least once are greater than 15 out of 16. by 70
tries,
32 out of 33. by 90 tries, greater than 99 out of a 100.

that oak tree standing on the hill would be toothpicks by the end of the
second
season.

Understand that in central Florida they receive more than 100 electrical
storms
each year. a 5% chance of getting struck would mean central Florida has
never
had trees.



How do you define "effective" area?
Your equation assumes that any lightning within the effective area of
your
boat will strike your boat. If that were the case I'd be very afraid.

"Parallax" wrote in message
om...
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.

...

I found a web site that gave a strike rate of about .5 strikes/km^2/yr
but they did not say where they measured this. However, this means
that a lone sailboat with a mast 17 m tall would have a .35% chance
each yr of getting struck. This is an ideal situation though and may
not address the situation of a sailboat under a thunderstorm where the
strike rate/km^2 is hundreds of times higher. Because I know that the
strike rate in Fl is much higher than average, I'd want to double the
strike rate they give to be about 1/km^2/yr. This gives about a .7%
chance each yr of getting hit. Again, this does NOT address the
situation where you know the strike rate is much higer than average
(sitting under a storm). Based on math and observed strike rate, I
still think my estimate is good.








The Florida Sea Grant Programs paper "Lightning and Sailboats"
estimates that between 4% and 20% of sailboats moored in FL get struck
each yr. Mooring is very close to the case of being a LONE sailbaot I
describe. This is well in accord with my estimates.

Various web sites show the FL strike desnity being 10-30 strikes/km^2.

A LONE tall tree with 5%/yr chance of being struck could live at least
15 yrs having less than 50% chance of being hit. Note that in Central
Florida, there are few tall hills and fewer with lone tall trees.

My analysis appears to be correct.

As an experiment to test whether JAX believes what he says, I propose:

JAX come sailing here in N. Florida in thunderstorms of MY choosing.
He will get a choice of various boats but we remove any grounding
system and replace them with a system where he completes the circuit
across his chest. Prior to sailing (while I remain on shore
videotaping for everyones amusement), he takes out a term life
insurance policy with me as beneficiary for gretaer than the value of
the boat plus $50,000 (I will pay for this policy).
After emerging unscathed from each storm, i will buy him dinner and
pay his hotel bill for the night (we have to have a thunderstorm each
day I pay). After only 11 storms, i will thank him, pay his plane
ticket cost plus $1000 and agree that he is a great sailor. He can
then go back and tell everyone what cowards those Florida rednecks are
and I will agree. Furhtermore, If JAX is worried about sailing in
thunderstorm wind (I am) then he can use a powerboat with a suitably
tall outrigger.

If JAX truly believes what he says, he should jump on this opportunity
to make a fast $1000, get at least 11 days paid for in FL and get to
go sailing for free.

This offer is only good till Sept 10 because then storms start to
taper off in intensity. He must agree to hold me and the boat owner
blameless for any harm that befalls him due to lightning.

So JAX, put up or shut up.

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

On 11 Jul 2004 10:05:27 -0700, (Parallax)
wrote:
... I found a site giving the strike rate for Malaysia and remember
that only two places have a higher strike rate than Central FL,
Equatorial Africa and SE Asia. Malaysia has a strike rate of
25/km^2/yr. I remember that C. FL rate isnt too much smaller than the
highest so I assume 10/km^2/yr and you get (using my effective area)
of a 7% chance/yr of a LONE sailboat getting hit. I find this to be
VERY believable based on experience.
///
I have found web sites calculating strike probability and they all use
a formula similar to mine where effective area goes as the height
squared. However, none i have found specify the factor by wich to
multiply the height to account for electric field modification, they
just qualitatively say it goes as height squared or use empiracaly
derived effective areas.

Here's a possible reason for some lightning estimators using height
squared.

Electric utilities use a cone of protection of 60 degrees included
angle beneath a ground wire.

If one used this 60 degree cone, the surface area "protected" by a
mast, in this case the area at risk, would be pi r squared,
where r is given by mast height X tan 30 degrees = 0.577 X m.h.
so pi r squared is pi X (0.577 X m.h) ^2 = 1.047 X m.h.^2

In other words, mast height squared is a reasonable area at risk
using the assumptions given above.
Then instead of a 7% per annum risk in Tstorms,
the risk is about 0.26% p.a.

Brian Whatcott Altus OK

LIGHTNING STRIKE PROBABILITY
 

pair a lox, you certainly don't let anything let reality interfer with your
proclamations, do you.

pair a lox, wanna tell us again about your EE degree in physics? your
estimate
does not match up with the math you use to portray your estimate. fine EE
you
are, and in physics yet.

btw, if 4% to 20% of all sailboats mooring in the State of Florida get
struck
by lightning each year, no insurance company on the planet would insure any
boat in the State of Florida without a HUGE increase in premium as compared
to
the State of Georgia or the State of Alabama or the State of Texas of the
State
of ...


The Florida Sea Grant Programs paper "Lightning and Sailboats"
estimates that between 4% and 20% of sailboats moored in FL get struck
each yr. Mooring is very close to the case of being a LONE sailbaot I
describe. This is well in accord with my estimates.

Various web sites show the FL strike desnity being 10-30 strikes/km^2.

A LONE tall tree with 5%/yr chance of being struck could live at least
15 yrs having less than 50% chance of being hit. Note that in Central
Florida, there are few tall hills and fewer with lone tall trees.

My analysis appears to be correct.








I am aware that conventional math and physics do not work in JAXWORLD
so will be happy to go over the basic arithematic for anybody.

Concerning insurance, My insurance specifies where I keep my boat.
Long terrm storage on a mooring might nullify it. In N FL, moorings
are not very common. Most boats kept on moorings are lower value
boats so a significant increase in insurance cost isnt likely since a
lightning strike rarely involves any liability considerations. Most
lightning strikes do not sink a boat but they do wipe out electronics.
Experienced boaters in FL normally disconnect their instruments when
they leave their boat for any length of time due to the high
probability of damage from nearby strikes. Statistics show that most
sailboats will eventually get struck or be subjected to a nearby
strike at least once in their lifetime in FL. My own 23' boat once
had its VHF wiped out from a strike on a nearby pine tree, I learned
after that to disconnect the antenna. A review of damage seen by
marine surveyors will show that they commonly see lightning damage on
boats they survey although it is mostly in the form of spiderweb-like
discharge patterns in the glass. The average lightning strike will
produce damage of lower cost than the insurance deductible (remember,
this is only if no ppl involved, ie. at mooring).

LIGHTNING STRIKE PROBABILITY
 

Then instead of a 7% per annum risk in Tstorms,
the risk is about 0.26% p.a.

Brian Whatcott Altus OK


Brian, you confuse pair a lox when you talk rational.

LIGHTNING STRIKE PROBABILITY
 

I'd pay real money to watch that!

--


Keith
__
Giving money and power to government is like giving whiskey and car
keys to teenage boys. --P.J. O'Rourke, Civil Libertarian
" As an experiment to test whether JAX believes what he says, I propose:

JAX come sailing here in N. Florida in thunderstorms of MY choosing.
He will get a choice of various boats but we remove any grounding
system and replace them with a system where he completes the circuit
across his chest. Prior to sailing (while I remain on shore
videotaping for everyones amusement), he takes out a term life
insurance policy with me as beneficiary for gretaer than the value of
the boat plus $50,000 (I will pay for this policy).
After emerging unscathed from each storm, i will buy him dinner and
pay his hotel bill for the night (we have to have a thunderstorm each
day I pay). After only 11 storms, i will thank him, pay his plane
ticket cost plus $1000 and agree that he is a great sailor. He can
then go back and tell everyone what cowards those Florida rednecks are
and I will agree. Furhtermore, If JAX is worried about sailing in
thunderstorm wind (I am) then he can use a powerboat with a suitably
tall outrigger.

If JAX truly believes what he says, he should jump on this opportunity
to make a fast $1000, get at least 11 days paid for in FL and get to
go sailing for free.

This offer is only good till Sept 10 because then storms start to
taper off in intensity. He must agree to hold me and the boat owner
blameless for any harm that befalls him due to lightning.

So JAX, put up or shut up.

LIGHTNING STRIKE PROBABILITY
 

stay home, guys, hidden in the southwest corner of your reinforced concrete
basements. otherwise, YOU ARE GONNA DIE A CRISPY CRITTER DEATH!!!!!!!

Boo.

From: "Keith"
Date: 7/12/2004 6:48 AM Eastern Daylight Time
Message-id:

I'd pay real money to watch that!

--


Keith
__
Giving money and power to government is like giving whiskey and car
keys to teenage boys. --P.J. O'Rourke, Civil Libertarian
" As an experiment to test whether JAX believes what he says, I propose:

JAX come sailing here in N. Florida in thunderstorms of MY choosing.
He will get a choice of various boats but we remove any grounding
system and replace them with a system where he completes the circuit
across his chest. Prior to sailing (while I remain on shore
videotaping for everyones amusement), he takes out a term life
insurance policy with me as beneficiary for gretaer than the value of
the boat plus $50,000 (I will pay for this policy).
After emerging unscathed from each storm, i will buy him dinner and
pay his hotel bill for the night (we have to have a thunderstorm each
day I pay). After only 11 storms, i will thank him, pay his plane
ticket cost plus $1000 and agree that he is a great sailor. He can
then go back and tell everyone what cowards those Florida rednecks are
and I will agree. Furhtermore, If JAX is worried about sailing in
thunderstorm wind (I am) then he can use a powerboat with a suitably
tall outrigger.

If JAX truly believes what he says, he should jump on this opportunity
to make a fast $1000, get at least 11 days paid for in FL and get to
go sailing for free.

This offer is only good till Sept 10 because then storms start to
taper off in intensity. He must agree to hold me and the boat owner
blameless for any harm that befalls him due to lightning.

So JAX, put up or shut up.

LIGHTNING STRIKE PROBABILITY
 

"Keith" wrote in message ...
I'd pay real money to watch that!

I'd figger I'd sell the rights to a reality TV show called "Stupid is
as Stupid Does"

--


Keith
__
Giving money and power to government is like giving whiskey and car
keys to teenage boys. --P.J. O'Rourke, Civil Libertarian
" As an experiment to test whether JAX believes what he says, I propose:

JAX come sailing here in N. Florida in thunderstorms of MY choosing.
He will get a choice of various boats but we remove any grounding
system and replace them with a system where he completes the circuit
across his chest. Prior to sailing (while I remain on shore
videotaping for everyones amusement), he takes out a term life
insurance policy with me as beneficiary for gretaer than the value of
the boat plus $50,000 (I will pay for this policy).
After emerging unscathed from each storm, i will buy him dinner and
pay his hotel bill for the night (we have to have a thunderstorm each
day I pay). After only 11 storms, i will thank him, pay his plane
ticket cost plus $1000 and agree that he is a great sailor. He can
then go back and tell everyone what cowards those Florida rednecks are
and I will agree. Furhtermore, If JAX is worried about sailing in
thunderstorm wind (I am) then he can use a powerboat with a suitably
tall outrigger.

If JAX truly believes what he says, he should jump on this opportunity
to make a fast $1000, get at least 11 days paid for in FL and get to
go sailing for free.

This offer is only good till Sept 10 because then storms start to
taper off in intensity. He must agree to hold me and the boat owner
blameless for any harm that befalls him due to lightning.

So JAX, put up or shut up.

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

LIGHTNING STRIKE PROBABILITY
 

I'd figger I'd sell the rights to a reality TV show called "Stupid is
as Stupid Does"

the name of that show is "Stupid is as Stupid Claims a EE Degree in Physics"



--


Keith

LIGHTNING STRIKE PROBABILITY
 

On 8 Jul 2004 11:10:43 -0700, (Parallax) wrote:
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.
===================================

Here are a few more observation points to ponder:

Back in the late 80s or early 90s, there was a major sailboat race
around Long Island that got hit by a severe thunderstorm. Out of
about 200 boats that were entered, three were hit, and one of the
three was hit twice. Empirically that equates to a 2% chance.

Here's another statistic published today by the Lee County weather
service in SW Florida: A typical thunderstorm here will have about
500 cloud-to-ground strikes. A major storm (like the one we had
yesterday) will have about 3500 CTG strikes. If you assume that a
major storm takes in a 10 x 10 mile area, that is a 100 sq miles, and
with 35 strikes per sq mile. Let's assume that the odds of a solitary
mast being hit are 50% within 100 yards of a strike. There are about
310 100 yard squares in a sq mile and the odds of any one square
taking a hit are 35/310 or about 11% in a major storm, between 1 and 2
percent in an ordinary storm. Going with 50% odds, your chances of a
direct hit would be 5% in a big storm and less than 1% otherwise.

Here's another data point. In 35 or 40 years of boating, much of it
under sail, I've been through about 10 really major thunder storms,
maybe 50 of the ordinary sort, and have been hit once. No damage to
people or boat but we lost all of the electronics onboard except for
my hand held GPS. We don't even know for sure if it was a direct hit
but it was WAY too close for comfort and we were 300 miles off shore.

LIGHTNING STRIKE PROBABILITY
 

On 11 Jul 2004 22:06:29 GMT, (JAXAshby) wrote:

btw, if 4% to 20% of all sailboats mooring in the State of Florida get struck
by lightning each year, no insurance company on the planet would insure any
boat in the State of Florida without a HUGE increase in premium

===============================

All joking aside, insurance has gotten almost that bad in Florida.

LIGHTNING STRIKE PROBABILITY
 

All joking aside, insurance has gotten almost that bad in Florida.



That has to do with several hurricanes and not enough insurance premiums.

LIGHTNING STRIKE PROBABILITY
 

Wayne.B wrote in message . ..
On 8 Jul 2004 11:10:43 -0700, (Parallax) wrote:
Out of curiosity, I did a quick back of the envelope estimate of the
probability of a lone sailboat getting hit by lightning in a
thunderstorm.
===================================

Here are a few more observation points to ponder:

Back in the late 80s or early 90s, there was a major sailboat race
around Long Island that got hit by a severe thunderstorm. Out of
about 200 boats that were entered, three were hit, and one of the
three was hit twice. Empirically that equates to a 2% chance.

A small dataset but close enough to what I calculated.

Here's another statistic published today by the Lee County weather
service in SW Florida: A typical thunderstorm here will have about
500 cloud-to-ground strikes. A major storm (like the one we had
yesterday) will have about 3500 CTG strikes. If you assume that a
major storm takes in a 10 x 10 mile area, that is a 100 sq miles, and
with 35 strikes per sq mile. Let's assume that the odds of a solitary
mast being hit are 50% within 100 yards of a strike. There are about
310 100 yard squares in a sq mile and the odds of any one square
taking a hit are 35/310 or about 11% in a major storm, between 1 and 2
percent in an ordinary storm. Going with 50% odds, your chances of a
direct hit would be 5% in a big storm and less than 1% otherwise.

Once again, close to what I calculated (5%).

Here's another data point. In 35 or 40 years of boating, much of it
under sail, I've been through about 10 really major thunder storms,
maybe 50 of the ordinary sort, and have been hit once. No damage to
people or boat but we lost all of the electronics onboard except for
my hand held GPS. We don't even know for sure if it was a direct hit
but it was WAY too close for comfort and we were 300 miles off shore.