I understand your hesitance based on your (one?) experience with a customer's boat. I would urge you not to take this experience as representative; there could be LOTS of reasons your client is having difficulty, none related to the KISS-SSB ground system.
At the heart of your question is ERP....effective radiated power. There is no technical reason why ERP with the KISS-SSB (or any other effective radial system) would be on average less than with a "traditional" RF ground system. Actual measurements of ERP would be a non-trivial task due to the complexities involved. Some years ago now Gordon West attempted some rudimentary ERP trials with another boater and, basically, the results tended to de-bunk the ubiquitous "100 square feet of copper" myth which has been repeated in most texts and instruction manuals
for decades. Gordon found that a simple copper strip from the tuner to the nearest bronze thru-hull works fine.
While we don't have empirical ERP data, we do have the following knowledge to draw upon:
1. Boats with SSB ground installations based on radials of some type tend to have signals just as strong and often stronger than those with the more traditional ground systems
...copper, plates on the bottom of the hull
, etc. I observe this daily on the maritime nets. For the past several weeks I've been hearing/talking to a client with a KISS-SSB ground system as he moves down the ICW
. His signal is quite strong and doesn't lack anything compared to other boats.
2. One of the most effective long-distance antennas you can mount on a sailboat is a vertical dipole
, i.e., a plain old dipole mounted vertically with the lower end tied off near the deck
. This antenna doesn't require ANY type of external RF ground system. The lower half of the dipole serves as a very effective complement to the upper half, and generates a very good low-angle signal all around the boat. When you have a traditional backstay system, what you're effectively trying to do is created the lower half of the dipole....at varying frequencies. Radials tuned to 1/4 wave work very well in this regard.
3. Elevated radials work better than buried radials
. Those at deck
level or somewhat below should and do work very, very well.
4. The KISS-SSB radial ground system works on virtually all commonly used marine and amateur HF bands
. One nice thing about radials is that their electrical
length (different from their physical length) isn't really critical, i.e., they work across a pretty wide part of the band.
5. In several recorded instances, the KISS-SSB radial system has actually worked better
than traditional ground systems, helping to eliminate troublesome RFI. One well-known builder
in the Far East of high-quality long-range trawlers has adopted the system after finding that it virtually eliminated the interference
problems they were having with their autopilot
I'm not going to say that the KISS-SSB radial system will work better on your boat than any other radial or RF ground system, but I can say based on the six units I've handled and tested that it WILL work very well, is very easy to install, and is certainly worth the price
when compared to any real costs of trying to build one yourself.
RE: range potential, that's a loaded and unanswerable question since range depends on a whole host of variables, some of which change from minute to minute. What I can say is that I talk to boats every day with this system installed...sometimes over distances more than 1,000 miles on the 40-meter amateur band...and they have signals every bit as good as others.