There's a tremendous amount of erroneous and misleading information concerning RF grounds and counterpoises for marine
and ham SSB operation. Much of this has been carried for years in most books
ssb (though not ham, usually) and in manufacturers instruction manuals
The famous "100 square feet" appears over and over, referring to the need to hook up everything metal belowdecks to try to achieve 100 sq ft of area.
Unbelievably, authors have just repeated this garbage over and over, though hams have known for many years that it's just not true. Even the guru of marine SSB, Gordon West, debunked this myth years ago. In his experiments, a simple copper strap to the nearest bronze thru-hull did very well indeed.
Hams, military operators, and others have used radials for many years as effective RF ground systems for HF operation. It has been proven that elevated radials -- above the ground -- are even more effective than are buried radials or those lying on the ground.
The marine corollary has to do with "coupling to seawater". Many "authorities" say salt water
is such a great ground that you only need to "couple" to it -- directly or capacitatively -- to have a good RF ground system. Well, guess what? That's garbage, too!
IS indeed a good conductor, but it's primary use is for REFLECTING electromagnetic waves (radio waves) off its surface, and bouncing them up to the ionosphere. This doesn't require "coupling"...it only requires that the RF energy be generated and beamed/bounced over water.
There are numerous posts on RF grounds on this Board and others. I did a very long post on subject years ago on the SSCA Board and elsewhere entitled, "RF Grounds in the Marine Environment".
Bottom line: LOTS AND LOTS OF THINGS WILL WORK VERY WELL AS AN RF GROUND ON A BOAT.....radials, s/s rub rails, aluminum
toerails, pushpit/pulpit/lifeline complex, large metal structures like swim platforms, radar
arches, etc., etc. A simple ground strap to a nearby bronze thru-hull will work as well. And, guess what, you can even do without the thru-hull. It's really the copper strapping which serves as the RF ground.
Automatic antenna tuners in common use these days, like the Icom AT130/140 and the SGC SG-230, are so good they'll couple to almost anything. Sometimes they'll even tune when nothing is attached to them, which is not to say that in those circumstances they'll generate a good signal. Rather, they'll just trick the transceiver into believing that everything is OK by presenting a 50-ohm load, which is what the transceiver wants to see. And, after all, a dummy load is an excellent 50-ohm match, but you won't be transmitting very far with it :-)
However, given a fair chance by connecting some conducting wire to the antenna and ground lugs on these tuners, you can generate an acceptable to very good signal.
The KISS-SSB is a commercial
product which is extremely well made and has been experimentally developed for both the marine and ham bands. It works very well and is extremely simple to install. Since I'm a dealer, I can't say much more than I've said in the past. It works, and in many situations it's just the ticket.
Re: placement of whip antenna, you want a vertical antenna for HF to be placed low down to the water
, not high up (unlike VHF
where the opposite is true). This is so you can take advantage of a low vertical takeoff angle for long-distance communications
I haven't personally tried the GAM antenna but I've heard them on the air on various nets and I'm not impressed. They seem not to perform as well as other options, including insulated backstays
, verticals, "alternate backstay antennas", so-called rope
Here's a comparison of some of the antenna choices for marine operation: