Simon,
I can give you more details and information than you 'd ever desire. But, first some brief, direct answers...
[quote="simoncurrin" post=966]We have just removed our very corroded SSB ground plate and looking to replace. I came across http://www.kiss-ssb.com/vacations.html on the web which seems to be a much better solution in that there is no through hull or corrosion. Does anyone have any experience of this? It seems to good to be true.[/quote]
1) Save your money!!
The KISS-SSB Ground is a waste of money, as it will do little for you.
It will do nothing that a couple random-length, scrap pieces of plain copper wire (attached to your remote auto-tuner 's ground lug) would do. And the scrap pieces of wire are either cheap or FREE...
This has been proven by both scientific testing (see links below) and real world on-air testing, as well...
(it 's a shame that this hasn 't yet made it across the Atlantic....sorry about that, I should 've posted some of this here, last year!)
2) There is/was quite detailed discussions about the "KISS", on my side of the Atlantic for the past year or two.
Including photos of the inside of the KISS, as well as detailed spectrum traces (from my own tests last year) showing its lack of any real resonances. And, multiple on-air comparisons as well.
For LOTS of details, photos, and screen shots of the actual response of the "KISS" in various locations/configurations (including in my own lazarette), please have a look at these discussions.
(This first one jumps you into the guts of the discussion and gives you the best overall sense of the KISS....and the remaining ones bring you to the beginning, should you find yourself with days of spare time to read it all!)
http://www.ssca.org/forum/viewtopic.php?f=5&t=13490&start=75
http://www.ssca.org/forum/viewtopic.php?f=5&t=13490
http://www.cruisersforum.com/forums/f13/the-kiss-ssb-counterpoise-revealed-with-pics-56551-13.html
http://www.cruisersforum.com/forums/f13/the-kiss-ssb-counterpoise-revealed-with-pics-56551.html
3) For attaching your antenna tuner 's ground lug to the sea water (to utilize the sea water as your antenna ground/counterpoise), use of copper strapping is preferred, as 3" wide copper has 48% less inductance than 14 ga copper wire.
If you use copper strapping (of at least 0.012" thickness to 0.022" thickness) rather than the thin foil (of 0.002" - 0.003" thickness) sold by chandleries, etc. it will last a LONG time (many years...10+ years in most cases..)
And, if you paint the copper strapping before installing it (I use a clear lacquer paint), or paint / epoxy after installation, it will last decades (20+ years) without any problems....
See this discussion for the details of the inductance issues, copper strapping vs. copper wire..
http://www.ssca.org/forum/viewtopic.php?f=5&t=14156&start=15
4) As for "what" the antenna ground / counterpoise is supposed to do???
There have been many books written on the subject, and I cannot type it all here :)
(I did write quiet a bit in some of the above linked discussions, look at the last page of the Cruiser 's Forum thread...)
In brief, here is some of what I wrote last year:
Entire books have been written about counterpoises, etc......and written by guys with a far better understanding of the science than I...
(Yeah, I 'm good.....real good with antennas, counterpoises, etc....but I 'm no Walt Maxwell or L.B. Cebik, Frank Jones, Bill Orr, etc. etc....)
So, what to write here that anyone would believe????
Hmmm, I 'm not sure....(hopefully I 'll come up with some good ideas later....but 'til then, here a few quick things...)
The way we use antennas for HF comms on-board our boats, the "counterpoises" we use, function in multiple ways....depending on the freqs/band, length of antenna (backstay, whip, etc.), and exact design/lay-out of the counterpoise, any/all of the below are the primary ways our counterpoises function:
1 -- reduce/eliminate feedline radiation.....
2 -- on most freqs / bands, they provide "the other half of the antenna"..(allowing the antenna return currents traveling through the ground / sea water, to get back to the antenna feed-point / base of the antenna, more effectively)
3 -- shunt "un-radiated" RF to ground (reducing RFI, etc.).....
4 -- assist an antenna couple (auto-tuner) in making an adequate match..
(although, some may question the "necessity" of this last item these days, as our modern auto-tuners could match a " wire coat-hanger", etc.....what this last function gives us is, the ability of the auto-tuner to find a more efficient tuning regime, thereby allowing more of our transmitted power to be properly coupled TO the antenna...is it "necessary", no....is it "desirable", YES! )
One of the misunderstandings that always amazes me is that many do not grasp the "differences" between using the sea water as our antenna ground/counterpoise, vs. using an artificial counterpoise made up of "radials"...(little distinction is made, between different ground/counterpoise systems, but there are REAL differences!)
The simple fact that using wire radials as a "counterpoise" does work, and
the simple fact that using copper strap to connect to the sea water, using the sea water as a "counterpoise" also works.....
They are NOT mutually exclusive....they are just different.....
(on-board radial-type counterpoises are typically made to be resonant on certain bands/freqs, and work "good-enough" elsewhere......
and, sea water-type counterpoises are broadband, and typically also have a fair amount of copper strapping inside the vessel that is functioning as part of the "counterpoise", similarly to the fact that the GTO-15 wire leaving your auto-tuner IS part of your antenna....)
There are pluses and minuses in both.....(barnacles, installation time/effort, complexity, possibility of RFI, etc.)
They both work.....which one you choose depends on many variables....
What works well for one application / one owner, may not be optimal for another.....
But, in most installations/applications the direct sea water connection, utilizing the sea water as the primary antenna ground/counterpoise, works best!!!
I hope all of the above helps, and does not overly complicate/confuse??
Fair winds..
John
s/v Annie Laurie