In case your interested, this is how a “counterpoise” works. This is what your doing when you add the Tuner Ground to the boat.I know this is an advertisement for their system, but the principle is true. John S., made his own radial system.

 How it works.    Think of it like
this, you have 8 tuning forks all sitting in a line, of those 8, one of
them is a “C” note.  Now you can take another C note fork in your hand
and hit it and then silence it real quick and you will hear the C note
fork of the 8 ringing. It heard it’s harmonic frequency and vibrated
with it, and the others did nothing. Now let’s do this backwards, you
hit 7 of the 8 forks and not the C note, the extra C note fork in your
hand will not vibrate, but if you hit all 8 of them, the extra one in
your hand will vibrate, it has to hear the “C” note frequency to react
to it.  That is why the counterpoise has to have a length of the
frequency to pulse the radiating side of the antenna so it will transmit
that signal in that frequency chosen. Think of two magnets, if you put
the two north sides or south sides together they repel each other, if
your radiating antenna feels the same resonating signal close by, it
will then repel it’s signal out into the air. That is where the word
“counterpoiseâ€