In article ,
Mike Coslo wrote:

Well, I could be wrong, but if one side of the capacitor is on the
inside of the hull, and the other side is the sea water, is not the
motion of the ship going to affect that? ships move up and down quite a
bit, and low draft ones can have a *lot* of that hull out of the water,
and then a few seconds later have water coming over the bow.


We are not talking about 16 foot dingys here, we are talking about
vessels mostly over 30 feet in length, and usually with over 3 or 4 feet
of draft. Just how much coupling to the seawater you have is a function
of area of the inside capacitive plate, and the distance between it and
the seawater. If the dielectric distance is a few inches, and the inside
plate is below the waterline, then coupling will not change apperciably,
just because the water is sloshing around a bit on the hull. Even if
a bit of the surface area of the inside plate did come above the
waterline for a little while, say on a hard tack in a sail rig, the
coupling still wouldn't be appreciably reduced by loosing 5% of the
surface area. These are not really valid problems that one sees, when
operating MF/HF Marine Radios that have a decent, Low Impedance RF
Ground System installed in the first place. doing it right the first
time solves a lot of ills down the road, and skimping on the RF Ground,
is a presciption for disaster.


Bruce in alaska long time Marine RadioMan.......
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Bruce in Alaska wrote:
In article ,
Mike Coslo wrote:


Well, I could be wrong, but if one side of the capacitor is on the
inside of the hull, and the other side is the sea water, is not the
motion of the ship going to affect that? ships move up and down quite a
bit, and low draft ones can have a *lot* of that hull out of the water,
and then a few seconds later have water coming over the bow.



We are not talking about 16 foot dingys here, we are talking about
vessels mostly over 30 feet in length, and usually with over 3 or 4 feet
of draft.

I'm not so sure the exact size ship we speak of. But if you recall back
a long time ago when the original poster spoke of a hypothetical wire
not working at 4 feet underwater. I even suspect that a 30 foot vessel
might take greater than a 4 foot excursion, especially in your neck of
the woods!



Just how much coupling to the seawater you have is a function
of area of the inside capacitive plate, and the distance between it and
the seawater. If the dielectric distance is a few inches, and the inside
plate is below the waterline, then coupling will not change apperciably,
just because the water is sloshing around a bit on the hull. Even if
a bit of the surface area of the inside plate did come above the
waterline for a little while, say on a hard tack in a sail rig, the
coupling still wouldn't be appreciably reduced by loosing 5% of the
surface area. These are not really valid problems that one sees, when
operating MF/HF Marine Radios that have a decent, Low Impedance RF
Ground System installed in the first place. doing it right the first
time solves a lot of ills down the road, and skimping on the RF Ground,
is a presciption for disaster.

I don't doubt that the problem has been solved (if it exists in the
first place).

- 73 de Mike KB3EIA -

On Sun, 11 Jun 2006 21:33:51 -0400, Mike Coslo
wrote:
the original poster spoke of a hypothetical wire
not working at 4 feet underwater.

Hi Mike,

This hypothesis was a home-grown and hand rolled fantasy.

I don't doubt that the problem has been solved (if it exists in the
first place).

Oh, there is a problem alright: Making the lesson penetrate a quarter
inch of skull with more success than RF struggling through an
imaginary 4 foot skin depth of water problem.

73's
Richard Clark, KB7QHC

Richard Clark wrote:
On Sun, 11 Jun 2006 21:33:51 -0400, Mike Coslo
wrote:
the original poster spoke of a hypothetical wire
not working at 4 feet underwater.

Hi Mike,

This hypothesis was a home-grown and hand rolled fantasy.

I don't doubt that the problem has been solved (if it exists in the
first place).

Oh, there is a problem alright: Making the lesson penetrate a quarter
inch of skull with more success than RF struggling through an
imaginary 4 foot skin depth of water problem.

Which won't happen until we discuss this into showing how it is
impossible to put a radio on a ship! hehehe 8^)



- 73 de Mike KB3EIA -

In article ,
Mike Coslo wrote:

I'm not so sure the exact size ship we speak of. But if you recall back
a long time ago when the original poster spoke of a hypothetical wire
not working at 4 feet underwater. I even suspect that a 30 foot vessel
might take greater than a 4 foot excursion, especially in your neck of
the woods!

It really doesn't matter if the vessel has a draft of 4 feet or 24
feet,as the coupling to the seawater is to the hull/water boundry
which is the same as the surface of the water from the RF point of
view. Skin Effect, or Skin Depth @ any frequency is a Surface Effect
and that surface is the hull/water boundry, for any hull material.

Bruce in alaska
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