On Sun, 28 May 2006 04:59:49 +1000, bob wrote:

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.

Hi Bob,

As I offered some time ago, how deep is fairly immaterial and your
dismissal of "many sailing web pages, Icom" and so on to then come to
the conclusion that they are "clearly wrong" is not quite so clear
why.

There are only two paths to that ground system well below the skin
depth of salt water:
(1) Through the water;
(2) Through a lot of air within the boat.

For (1), that already takes care of itself, but is a very odd method
to getting to that dynaplate. Besides, a wire tacked to the outside
of the hull, or worse simple thrashing in the surf, has got to add to
drag. Following this wet path automatically snubs how much current
will make it to the plate anyway. As Reggie offers, after 40 inches
at 7MHz it is immaterial and that wet path to the plate makes the
plate simply a tie-point. In short, you have to penetrate that skin
depth to get beneath it. Penetrating it solves the "problem" of going
too deep.

For (2), what do you stand to lose with a deeper connection that is
approached through the interior of the boat? This is a matter of
matching characteristics, which lead to issues of loss. You have the
same connection loss anyway you look at it.

So, what value is there in these page's recommendations? It insures a
connection.

Of course, I could be wrong. I've only had experience in electronics
on Big Gray Boats in salt water, or in Big Gray Submarines beneath
salt water. Ground was everywhere and death as far away as a power
lead (several dozen nuclear warheads were only slightly further away).

73's
Richard Clark, KB7QHC