In article ,
"Vito" wrote:

Tests of mobile antennae in the Amateur Radio 75 meter band (4MHz) yielded
the following results:

* Well-designed Bugcatcher or Screwdriver with top hat 0 dB reference
* Bugcatcher or Screwdriver with no top hat -3 dB
* Hustler or Outbacker -9 dB
* Hamstick -12 dB
* Whip with autotuner -14 dB

This suggests that the common insulated-backstay-with-autotuner used on
sailboats could be improved by adding a capacitive top hat immediately below
the upper insulator and/or a tapped coil in parallel (ie around) the lower
insulator to tune whatever length of antenna one can physically accomodate
to resonate on or near the Marine frequencies of interest, such as 2182 MHz.
Has anyone any experience doing so?

Most noncommercial boaters do not have the expertiese to understand,
let alone install, what you are describing. Most commercial vessels
have enough Mast Height to accommodate a "Total Antenna Length" of 75 ft
so that common autotuners can resonate the system to 2182 Khz. On
SOLAS Required Vessels MF and HF Antenna Systems are designed to
be resonate on all the specific SOLAS Required Frequencies and are
TESTED and Logged once a year by Licensed Marine Radio Tech's.

Bruce in alaska
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add a 2 before @