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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.

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.

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