bob wrote:

I dont have NEC4 is it too much to ask you to run the model. Radials
over sea water versus a direct connection?

Sure. How many, how high, and how long? The foot-long wire produces
efficiency of virtually unmeasurably close to 100%. So radials can't be
significantly better. What sort of efficiency are you expecting from the
radials?

[I wrote:]
Certainly elevated radials would be better than metal more than a skin
depth or two deep. Better yet is a wire extending from the surface to
a few skin depths. Why isn't that possible?

Theres no easy way of making sure that the wires will submerge
precisely or close to the ideal skin depth. The loading and heeling of
the yacht would affect this depending on the sailing position wind
speed and other factors. The motion of the waves and swell conditions
will also be another variable. It would work great when you anchored.

Why can't you extend a wire or strip all around your boat, or make it
several feet long? There's no penalty for having it extend beyond
several skin depths. Fishermen somehow manage to keep their lines and
nets in the water -- surely you can work out a way to keep a wire in the
water.

Well if you read the many sailing web pages and the Icom marine
guides they all advocate installing your RF ground system well below
the skin depth of salt water. They also advocate bonding all your on
board metals to submerged objects like the keel and copper ground
shoes, which is clearly wrong.

Yes. There's a vast amount of incorrect information on the web. Have you
ever browsed around audiophile pages dealing with speaker wire? I'm sure
there are innumerable astrology pages, too.

A yacht with elevated radials installed below the deck would radiate a
better signal in my view. However what constitutes an effective radial
system over seawater for frequencies between 1 and 30 mhz using a
random wire backstay antenna versus a direct connection to sea water i
cant answer without the modeling software.

All I can do is present the results that physical laws dictate. It's not
uncommon for that to be inadequate to change a person's beliefs.

Roy Lewallen, W7EL