On Wed, 7 Apr 2010 13:51:18 -0700 (PDT), Bil
wrote:

That dock idler reckons the ATU would tune the whole rig. And that
more metal in the antenna is effectively better.

Is this madness? Heresy? Or makes sense?

Quite possibly all of the above depending on your opeating frequency
and how the base of your mast and shrouds are grounded, or not.

In other words it might work, and it might not. Would it do damage
to try it out? Hard to say but you might very well end up with high
RF voltages in places where you don't want them.

I'd leave it alone. The tuner is designed to work with a fully
insulated backstay or an insulated whip antenna in the range of 17 to
27 feet long, fed at the base. Anything else, you're in uncharted
territory. I'm operating an ICOM ATU into a 23 ft whip and it works
fairly well on all HF frequencies. The most important part of the
antenna is a good ground system.