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 -