I always thought >gain< was a function of the antenna design, and has to do
with the radiation pattern from the antenna becoming more horizontal and
less spherical, but conventional wisdom holds you don't want a really high
gain antenna on a sailboat because the horizontal radiation pattern doesn't
help you much when heeled. I think west marine recommends a 3db gain for
monohull sailboats, while I think I've seen antenna designs with as much as
9db gain for trawlers and multihulls.
Since VHF is basically line-of-sight, height increases the range for the
same reason a taller light can be seen further.
But I don't believe height itself increases gain.
> What is the maximum height that I can put my antenna
> without blowing out or overloading the radios of the adjacent boats?
I wouldn't worry about it if your running normal (<=25watt) power. As a
courtesy to others you should try to low power setting to reach your target
before trying the high power. I've never heard of anyone blowing out an
adjacent boats radio.
or are you pulling our legs again?