"Larry W4CSC" wrote

Actually, in a plastic boat, the radiation from the ground strap is useful
radiation. You've just moved the FEEDPOINT up the radiating element above
the sea. My feedpoint is about 4.8' above ground on Lionheart. It's
signal strength 5, readability 8 in Moscow, Belarus, UAE, Japan, Brazil,
most of Western Europe on 40 meters and 20 meters. Works pretty good!

Larry, we've probably had the details of this antenna system in pieces
across various posts, but would you mind putting in one place here? Sounds
like an intersting and well thought out setup.

Thanks,

Jack

"Jack Painter" wrote in
news:Vlxxc.5736$5B2.5631@lakeread04:

Larry, we've probably had the details of this antenna system in pieces
across various posts, but would you mind putting in one place here?
Sounds like an intersting and well thought out setup.

Thanks,

Jack

It isn't very fancy, actually. The Icom AT-140 tuner is screwed to the top
of the aft cabin just aft of the mizzen mast, which is deck stepped. The
HV RF output post is about 8" from the base of the insulated backstay on
the main and a short, smoothly bent piece of #12 Copperweld antenna wire is
hose clamped to the Amel's backstay jack out of the way of the winch handle
socket. The insulator is about a ft from the mast at the top and every
time I look up there I want an insulator on each end of the triatic stay
with an interconnecting Copperweld wire connecting the top of the backstay
antenna to the center of the insulated triatic to make it a capacitor hat
on top of the 50' sloping vertical for the lower frequency bands. If it
ever goes back into the yard for demasting, it will have it...(c; But, for
now, it just has the backstay.

When Geoffrey got the boat, the previous owner reported poor performance
(he was a ham, too) from the backstay antenna, which I traced down to
loading from the stainless cable topping lift on the large main boom,
sucking off the signal to the mast because when the boom was centered, it
was only a few inches from the backstay. Not good. So, we changed the
stainless to nylon and now no metal gets near the antenna, no matter where
the boom is set. Signal reports came up a LOT!

Directly beneath the tuner, in the support for the deck stepped mast, are
several storage holes I can put wires into. So, I got a #8 battery wire,
black of course, and put a ring terminal to fit the ground post on the
tuner on one end. As straight as I could, I routed it down through the
openings in the mount into the engine compartment which is right under the
mast. Directly under the tuner, too, is the DC shunt used for the ampere-
hour meter on the house batteries under the shunt. This great ground, to
the big 700 AH house batteries against the hull, and the whole house ground
system, is tied in at the shunt, then the cable drops straight down to the
engine block for more grounding and capacitive coupling through the hull.
Antenna current came way up as did signal reports from this installation.
Dropping a bare Copperweld wire over the side I use for even more grounding
while underway at sea, I measure only about 1.5 ohms from the bare wire
laying on the bottom of the marina and this ground connection above.
Something's got a great connection to the ocean down there. I musta got
lucky.

That's it. The radio is grounded to a ground strap Amel installed behind
the panel behind the chart table. It's a common ground strap where all my
instrumentation, navigation and communications is tied with small wire.
There is a direct connection between that strap at the nav station and the
engine block and house ground, too. I like to think it may bypass some
static hits, but haven't been through any on this boat....yet. Let's not
rush the testing of this theory.

Larry W4CSC

"Larry W4CSC" wrote

It isn't very fancy, actually. The Icom AT-140 tuner is screwed to the
top
of the aft cabin just aft of the mizzen mast, which is deck stepped. The
HV RF output post is about 8" from the base of the insulated backstay on
the main and a short, smoothly bent piece of #12 Copperweld antenna wire
is
hose clamped to the Amel's backstay jack out of the way of the winch
handle
socket. The insulator is about a ft from the mast at the top and every
time I look up there I want an insulator on each end of the triatic stay
with an interconnecting Copperweld wire connecting the top of the backstay
antenna to the center of the insulated triatic to make it a capacitor hat
on top of the 50' sloping vertical for the lower frequency bands. If it
ever goes back into the yard for demasting, it will have it...(c; But,
for
now, it just has the backstay.

When Geoffrey got the boat, the previous owner reported poor performance
(he was a ham, too) from the backstay antenna, which I traced down to
loading from the stainless cable topping lift on the large main boom,
sucking off the signal to the mast because when the boom was centered, it
was only a few inches from the backstay. Not good. So, we changed the
stainless to nylon and now no metal gets near the antenna, no matter where
the boom is set. Signal reports came up a LOT!

Directly beneath the tuner, in the support for the deck stepped mast, are
several storage holes I can put wires into. So, I got a #8 battery wire,
black of course, and put a ring terminal to fit the ground post on the
tuner on one end. As straight as I could, I routed it down through the
openings in the mount into the engine compartment which is right under the
mast. Directly under the tuner, too, is the DC shunt used for the ampere-
hour meter on the house batteries under the shunt. This great ground, to
the big 700 AH house batteries against the hull, and the whole house
ground
system, is tied in at the shunt, then the cable drops straight down to the
engine block for more grounding and capacitive coupling through the hull.
Antenna current came way up as did signal reports from this installation.
Dropping a bare Copperweld wire over the side I use for even more
grounding
while underway at sea, I measure only about 1.5 ohms from the bare wire
laying on the bottom of the marina and this ground connection above.
Something's got a great connection to the ocean down there. I musta got
lucky.

That's it. The radio is grounded to a ground strap Amel installed behind
the panel behind the chart table. It's a common ground strap where all my
instrumentation, navigation and communications is tied with small wire.
There is a direct connection between that strap at the nav station and the
engine block and house ground, too. I like to think it may bypass some
static hits, but haven't been through any on this boat....yet. Let's not
rush the testing of this theory.

Larry W4CSC

Sounds great Larry, Thanks. Seen in a Univ of Florida study, paraphrased:

1. All boats can be struck by lightning, protected or not, and
2. Protected boats and unprotected boats both suffer damage when hit, and
3. Unprotected boats suffer significantly more damage than protected boats.

It sounds like you and Lionheart are well protected.

I remember a night of terrible line squalls that wrecked several yachts in
Block Island Salt Harbor. I had stayed up on deck with gear on as I knew it
was coming as I returned from a night on the town. It was worse than any
summer line squall should have been! By the time I roused my family the
winds had the entire harbor dragging anchor. Anyne who has been there can
imagine the panic of watching your Out Island 41 heading toward mega-million
yachts both dragging along with you, and lining the docks for a busy
weekend. The Westerbeke diesel with one anchor could not hold us, and I went
forward to set a second anchor and lots of chain with it. I think there must
have been hundreds of lightning srtikes all around us without any break
between them. Night turned to day, and that helped avoid touching shrouds
while on deck. Everything around us seemed to be getting hit, and of course
it was one of those moments when (at least I) thought I was going to die
from lightning at any moment. But the second anchor and the diesel held us
just short of one of the hundred-footers at the outer docks. In the
aftermath, we heard there was a lot more damage from collisions than from
lightning, and that is amazing considering how many yachts I saw get struck
that night.

Best,

Jack

"Jack Painter" wrote in
news:16syc.157$Jk5.41@lakeread02:

outer docks. In the aftermath, we heard there was a lot more damage
from collisions than from lightning, and that is amazing considering
how many yachts I saw get struck that night.

I've read the webpage from FL. Very interesting research. The mast looks
tall when you're standing at the bottom of it looking up, but in the
overall height of a thunderstorm FIVE MILES HIGH, our masts are like a
dimple on the dining room table, and not much of a "target".

I was at the transmitter shack of WRJA-TV, the PBS station in Sumter, SC,
visiting an old friend who was chief engineer, Bill Jones, one night. We
were building the first weather radio repeater after Bill had applied for,
and gotten, an FCC license for that band to simply repeat the signal from
Columbia, SC's weather station to the local Sumter area which had trouble
hearing it. We made it out of kit ham radio repeater boards from VHF
Engineering in Binghamton, NY, as we had a local repeater.

A huge thunderstorm cell moved across Sumter and actually went THROUGH the
1800' WRJA-TV tower while we watched out the back door as lightning went
SIDEWAYS 10 miles in the cloud just to hit that big 1800' ground rod
sticking up out of the table-flat terrain of eastern Sumter County. I'm
standing there watching the light show and suddenly Bill taps me on the
shoulder and hands me a big yellow rain coat, saying, "Come on. I wanna
show you something neat." We followed the huge hardline coaxial cables
from the 35KW TV transmitter out to the base of the antenna and Bill says,
"You're standing in the safest place in Sumter County. There is a cone of
protection against being hit by lightning provided by my tower and you're
now standing in the middle of it. Hang onto the tower leg and feel the
current going through it." I burned my hand a couple of times as the huge
BOOMs went off over my head a thousand feet up. The huge bridge cables
JUMPED from the surge of electrical EMP hit them, many times. The lights
went out and we had to go back in the building to reset the transmitters
when the power came back on.

Though the "tower" on the sailboat is very short, in comparison, I like to
think that if you have a proper grounding system, like the professor
describes on his webpages, you are also in a tiny cone where the blast will
mostly be shunted AROUND you, which is why your car is so safe in a
thunderstorm. The current surge that kills goes AROUND the the steel body
of the car....Steel ships and boats do that....Plastic, not so good.

Larry

On Sun, 13 Jun 2004 02:26:00 -0000, Larry W4CSC
wrote:

"Jack Painter" wrote in
news:16syc.157$Jk5.41@lakeread02:

outer docks. In the aftermath, we heard there was a lot more damage
from collisions than from lightning, and that is amazing considering
how many yachts I saw get struck that night.

I've read the webpage from FL. Very interesting research. The mast looks
tall when you're standing at the bottom of it looking up, but in the
overall height of a thunderstorm FIVE MILES HIGH, our masts are like a
dimple on the dining room table, and not much of a "target".

I was at the transmitter shack of WRJA-TV, the PBS station in Sumter, SC,
visiting an old friend who was chief engineer, Bill Jones, one night. We
were building the first weather radio repeater after Bill had applied for,
and gotten, an FCC license for that band to simply repeat the signal from
Columbia, SC's weather station to the local Sumter area which had trouble
hearing it. We made it out of kit ham radio repeater boards from VHF
Engineering in Binghamton, NY, as we had a local repeater.

A huge thunderstorm cell moved across Sumter and actually went THROUGH the
1800' WRJA-TV tower while we watched out the back door as lightning went
SIDEWAYS 10 miles in the cloud just to hit that big 1800' ground rod
sticking up out of the table-flat terrain of eastern Sumter County. I'm
standing there watching the light show and suddenly Bill taps me on the
shoulder and hands me a big yellow rain coat, saying, "Come on. I wanna
show you something neat." We followed the huge hardline coaxial cables
from the 35KW TV transmitter out to the base of the antenna and Bill says,
"You're standing in the safest place in Sumter County. There is a cone of
protection against being hit by lightning provided by my tower and you're
now standing in the middle of it. Hang onto the tower leg and feel the
current going through it." I burned my hand a couple of times as the huge
BOOMs went off over my head a thousand feet up. The huge bridge cables
JUMPED from the surge of electrical EMP hit them, many times. The lights
went out and we had to go back in the building to reset the transmitters
when the power came back on.

Though the "tower" on the sailboat is very short, in comparison, I like to
think that if you have a proper grounding system, like the professor
describes on his webpages, you are also in a tiny cone where the blast will
mostly be shunted AROUND you, which is why your car is so safe in a
thunderstorm. The current surge that kills goes AROUND the the steel body
of the car....Steel ships and boats do that....Plastic, not so good.

Larry


Larry, I really don't believe you are that dumb to hold on to a tower
in the middle of a lightning storm. I do see that you are a great
story teller though. However please remember that there are a lot of
folks that read this group that may not be too technically savvy and
may not be able to tell the difference.

Regards
Gary

Gary Schafer wrote in
:


Larry, I really don't believe you are that dumb to hold on to a tower
in the middle of a lightning storm. I do see that you are a great
story teller though. However please remember that there are a lot of
folks that read this group that may not be too technically savvy and
may not be able to tell the difference.

Regards
Gary


Not dumb at all. Under my feet were 36 pile-driven ground rods connected
with bridge cables to the tower in a ring about 100' in diameter, "driven
to refusal", in other words, bed rock.

The several megohms of body resistance is no path at all when in parallel
with a few MICROOHMS to such a ground system. With currents high enough to
heat the tower beyond what my hand could tolerate, there is no shock, at
all.

It was a most amazing afternoon.....(c;

Larry

On Sun, 13 Jun 2004 13:57:17 -0000, Larry W4CSC
wrote:

Gary Schafer wrote in
:


Larry, I really don't believe you are that dumb to hold on to a tower
in the middle of a lightning storm. I do see that you are a great
story teller though. However please remember that there are a lot of
folks that read this group that may not be too technically savvy and
may not be able to tell the difference.

Regards
Gary


Not dumb at all. Under my feet were 36 pile-driven ground rods connected
with bridge cables to the tower in a ring about 100' in diameter, "driven
to refusal", in other words, bed rock.

The several megohms of body resistance is no path at all when in parallel
with a few MICROOHMS to such a ground system. With currents high enough to
heat the tower beyond what my hand could tolerate, there is no shock, at
all.

It was a most amazing afternoon.....(c;

Larry


With the high current traveling through the tower and the relatively
high impedance that the tower and ground leads present, it is possible
to have thousands of volts differential in only a few feet length. The
larger the tower the less impedance of course. But the ground system
is never 100% and it has it's own impedance problems.

All conductors have impedance and a high current applied to that
impedance will produce a large voltage drop across it. Even the tower
itself.

Ground rods driven past 8 to 10 feet do little good for lightning.
Even if they are into the water table past that depth. The impedance
of that long of a rod gets to high to be of much value. (I know, lots
of people have long deep rods or pipes in their installations and
think they have the best ground in the world)

If you really want to know why go look at the polyphaser site. They
even tell you how to calculate what the voltage drop in a few feet of
tower length will be with a typical lightning strike.

You are right about the tower providing a "cone of protection" but
that cone only means that the lightning will probably strike the tower
before it strikes you directly. It does not tell you anything about
how effective the tower / ground system is at getting the lightning
current dissipated safely to ground.

Don't be grabbing on to those towers during a storm Larry. We will
miss you here.

Regards
Gary

"Larry W4CSC" wrote

"Jack Painter" wrote

outer docks. In the aftermath, we heard there was a lot more damage
from collisions than from lightning, and that is amazing considering
how many yachts I saw get struck that night.

I've read the webpage from FL. Very interesting research. The mast looks
tall when you're standing at the bottom of it looking up, but in the
overall height of a thunderstorm FIVE MILES HIGH, our masts are like a
dimple on the dining room table, and not much of a "target".

"You're standing in the safest place in Sumter County. There is a cone of
protection against being hit by lightning provided by my tower and you're
now standing in the middle of it. Hang onto the tower leg and feel the
current going through it." I burned my hand a couple of times as the huge
BOOMs went off over my head a thousand feet up. The huge bridge cables
JUMPED from the surge of electrical EMP hit them, many times.

Though the "tower" on the sailboat is very short, in comparison, I like to
think that if you have a proper grounding system, like the professor
describes on his webpages, you are also in a tiny cone where the blast
will
mostly be shunted AROUND you, which is why your car is so safe in a
thunderstorm. The current surge that kills goes AROUND the the steel body
of the car....Steel ships and boats do that....Plastic, not so good.

Indeed. That Florida study explains that there are very few examples of
sailors (on sailboats) being hurt or killed by lightning. That is due to the
cone of protection as you said, but it does not normally extend to anyone
touching those shrouds or mast! To some extent you are bonded to the system
when standing on deck and could be in a very high voltage condition without
feeling much current due to the bonding. While HV lineman aloft use that
principle safely every day, boaters are advised to remain below deck and NOT
touch anything conductive during a lightning storm.

Similarly, while "under" the cone of protection of that high transmitter
mast, you were indeed safe. But on your way over to it and back from it, you
are both lucky you lived to tell the story. The voltage gradient between
your two feet on the walk nearby could be thousands of volts during a
discharge let alone a strike.

Best regards,

Jack

On Fri, 11 Jun 2004 20:27:40 -0400, "Jack Painter"
wrote:

I remember a night of terrible line squalls that wrecked several yachts in
Block Island Salt Harbor.

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

Would that have been in the summer of '74 by any chance? I was
halfway between Mystic, CT and BI that year when we got hit by the
mother of all line squalls just after dark.

"Wayne.B" wrote

On Fri, 11 Jun 2004 20:27:40 -0400, "Jack Painter"
wrote:

I remember a night of terrible line squalls that wrecked several yachts
in
Block Island Salt Harbor.

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

Would that have been in the summer of '74 by any chance? I was
halfway between Mystic, CT and BI that year when we got hit by the
mother of all line squalls just after dark.

It was the summer of '85. I lived in Mystic from '84 to '87 right at the
drawbridge, in what turned out to be the only building on the water that did
not burn from Gravel Street to the drawbridge, a few years back.

Best regards,

Jack