Change HF-SSB antenna on sailboat

[Goudurix]

Hi,
Until now I had a 9,2 m sloping wire (halyard to transom) as HF antenna.
Due to the installation of an A-frame and a bimini I would have to move this wire more outward and via standoffs on the A-frame until the through-deck lead to the ATU.
This makes the wire slope even less "vertical".

Through antenna modeling I found out that a 7,2 m vertical whip gives a cleaner and better predictable radiation pattern. I would also have to install it outside of the A-frame, starboard side. Not an easy installation.

Is it worth the effort to go for the vertical whip or should I change the sloping wire as explained above and not bother with the increased directivity of a less steep sloping wire?

My main use is Winlink comm for grib files and HAM voice and digital comm for fun.

Thanks for any advice or comment,

Jan ONZTT/MM

[tkeithlu]

K4TKL here. Disclaimer - antennas are not one of my ham strengths. But, from a practical standpoint, I recommend that you install the old sloping wire and give it a test. My bet is that you'll be OK, and it's not that difficult to use it from the dock to contact a few other hams on any given morning. If there's an objectionable loss, or you are dead on the side that radiates into the water, then go with the whip. I use a whip, not having a mast slope above 45 degrees; it needs support part way up.

[S/V Illusion]

If you modeled the 7.2M vertical, you should also be able to model the effect of changing the sloper angle on radiation pattern.

The directivity of a sloper is well known, however, slight changes in its angle make little difference.

[Goudurix]

Hi S/V Illusion,

It's been years since I did the modeling and I don't have the software installed on my new laptop and it would take quite a while to re-model the boat with its mast, shrouds, guardrail .....

Also I now added the A-frame at the transom.

But indeed re-running the sloper is the easiest way and I'll see how that works out.

Regards,

Jan
ON3ZTT/MM