Brett,
The common practice of insulating the backstay on a sailboat
ABOVE the point where casual human contact can take place, is
driven by personal safety considerations. An insulated wire
running from the below-deck tuner TO that backstay antenna is
a safer approach than lowering the insulator.
On a 30' sailboat, for casual, coastal cruising, antenna
selection is a real debate. One thing I'd try is a hamstick
off the transom...or on a stern pulpit mount, fed through
an automatic tuner like the SGC or Icom AH4, against ground.
Design for 1/4-20 mount, and you can experiment with various
hamsticks, and perhaps an outbacker in the same setup.
Previous comments in respect to ground are noted; this is
actually the more challenging aspect of the installation.
If anybody is interested, I'd discuss it off reflector.
Jim/N2EA
Message: 12
To: <towertalk@contesting.com>
Date: Sat, 06 Jul 2002 01:50:45 +0000
To: towertalk@contesting.com
From: VR2BrettGraham <vr2bg@harts.org.hk>
Subject: Re: [Towertalk] 20m Antennas for sailing
I agree with AC7NJ - insulated backstay is the way to go on a sailboat. I have
done this on a number of boats here over the years.
If the boat is not to be scrutinized for off-shore racing, then one can do
it right -
break the lower end of backstay with an insulator right at the deck & place the
tuner under the deck at that point.
For some reason, common practice is to break the backstay a few meters up
from the deck & then bring a length of coax down from there. I would expect
that the aim of keeping the lower end "cold" will be lost as depending on
length
& frequency, the "feeder" could be awfully hot & will be coated in salt water
itself.
The likelihood of someone using the radio whilst crew are hanging on to the
backstay is slim & IMHO one can do better insulating with a shroud of some
sort - therefore being safer & electrically better.
Another sailing antenna solution I would like to try for somebody someday is
to put something like an IsoLoop on top of the mast.
W1ECT mentioned AA1XO/MM's boat is a bit of a dinky toy, so a permanent
antenna might be overkill, in which case I would be tempted to use something
based on my preferred backup antenna - fiberglass fishing pole strapped to
the aft railing: makes for a great wire vertical support & one can simply drop
a wire into the water to complete the other half.
73, VR2BrettGraham
Jim Jarvis
Keithley Instruments
Essex Vermont
802 872 5830 voice
802 872 5831 fax
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