Roger wrote:

I am installing an Icom 802 ssb with a 140 tuner. I am looking for
advice/experience on the difference in performance between
Shakespeare's 17'6" whip vs. the 23' whip.

I have a sloop with a split backstay and probably will go with a
whip.I only have about 3' between the antenna base and the mounting
clamp on the transom. Insulating the backstay and running the feed
wire along the split (through the bimini) is my second choice.

The length of your boat and backstay might help us, here for the
number crunchers.

Test Receiver (Rx) side first, manually adjusting tuner with power
off. Rx adjustments will be similar, reflecting Transmit (Tx) potential.

Consider not insulating your backstay. Just disconnect it's ground /
bonding at the transom. Insulate it with hose to transmit. Feed
point by hanging coax centre only to the midpoint of the split, or
insulate one leg of split from the centre or base and feed the other
bottom. Leave coax shield unconnected at Antenna feed point.
Experiment with directivity and relative sensitivity by monitoring a
distant transmitter while you power in a circle, or adjust matching.

You might be able to tune some by shortening the coax shield and /
or connecting the shield end at the maching box or transmitter by
switching R.F. capacitors in series with the shield, or
disconnecting the shield from ground and connecting it to Tx ground,
chassis or power lead ground. It is generally not good to use DC
wiring as part of the Antenna Counterpoise, but sometimes it will
work a miracle. Consequential lightning or static damage can occur,
frying other stuff. Methods abound.

This method of grounding can be like connecting a welder /
commercial electroplater to your prop and zincs, etc. unless they
are isolated, insulated from ground bonding and R.F. sources. R.F.
capacitor bondings can also be cobbled to lifelines, etc, sometimes
to good effect.

At R.F. distances from the ground connection, ground or power return
wires can become energised WRT other elements, acting as
counterbalancing antenna elements. Here, the more the better, except
for errant pedestrians.

Antennae are like cat's wiskers, sensing the wind is easier with
differential signal sensitivity, like hearing sonar returns through
multi-mike differential time delay systems, steering the sense of
hearing.

Some bondings are to be avoided. Polarisation can also be fiddled,
with goniometer tech and time delay devices.

Understanding R.F. and ground / counterpoise / lightning plans is a
heated subject, hereabouts.

Much fun to watch.

Terry K