I had a CAT with a short stay on the port side as the antenna
. It looked feasible for an antenna
and may have been interesting. However, as you suggest there are many other implications on a boat that can make it a lot more challenging than ashore.
As stated earlier I check over 40 boats a year here in the Sea of Cortez
. While we have been really talking about theory of installations. The reality is quite different.
The average cruiser typically does not understand HF SSB
. They were an expert in another field before they retired. When faced with the option of cutting the back stay and putting holes in the boat to make it work, they resist and look for other options. Isolated backstay and dynaplate maybe the best around solution. However I think the boat has a lot to do with it. Here in PV, we have a local SSB
net. It is all ground wave.
The boats in La Cruz have various configurations. One of the boats has copper plates connected by copper strips (all isolated from DC ground) with an isolated backstay. They seem to be able to hear better than even the shore stations in the net. As far as transmitting they are always good. However the Cat with a Kiss Ground on the other side of the same dock
with a 24 foot fiberglass
pole was stronger today, but could not hear the contact south of us.
One of the boat with the dynaplate and Isolated backstay has been the weakest in the Sea of Cortez
. Seems to hear OK, but the boats in the same anchorage, some may even have Dynaplates, are 2-3 bars stronger.
About 30-40% of the installations down here are by the owners. Another 30-40 are by individuals that define them selves as experts and the rest are by good technical folks, maybe even real experts.
e.g. Last spring in Mazatlan I found one of the "defined expert installations" with max SWR on my meter. Long story short, he used GTO15 high voltage cable between the transceiver and the antenna tuner. The boat was using a Gamm antenna. The extra HV wire had been coiled into a 5" loop and tie wrapped to a metal bracket.
A boat I checked 2 days ago because of poor output here in the marina had inserted a piece of # 6 wire with about 10 MOVs in Parallel, that in series with another piece of wire and then to the Dynaplate ground connection on the AT 140 tuner. The Dynaplate was also hooked into the boats bonding system.
I could go on for hours.
Most of the ones installed by the owners are OK, some not great, but OK.
With the use of a Gamm and Kiss ground, there are usually minimal technical issues. They are installed they way the manufacture has specified. While communicating within the nets, the boats that do not communicate well are ones with issues. The ones that excel, strong transmission
, vary with products used.
As a result I typically do not badmouth any of the products used, except using a Ham radio
instead of a Marine radio
. Even that works for the Ham that put the radio in, but the second owner on those boats seem to always have issues. The Ham radio is never straight forward to do the marine
things like Airmail. (Airmail does support a few Ham radios, but not Icom
which seems to be the most popular, probably a cost factor.)
In saying all of this, while it may work fine to do an inverted V using 2 stays, with a 50 foot mast
and 14 foot beam, the length of the wire is probably to short for anything below 4.4 MHz and ~16 degree angle between the elements would be to small for a typical inverted V. The tuner at the top of your mast
would be interesting and would probably require a special control cable with larger wire. Alternatively you could run transmission
line from the tuner to the top of the mast, but there you have losses and the standard Marine grade tuner below would not compensate for transmission line and the antenna so you may well have high losses from cable length and SWR.
Bottom Line the systems now being used on boats work reasonably good. Nothing like our MARS station back home, but good. Because it is typically a back stay antenna, it is slightly directional from the stern. The key is make sure your connections are not corroded and use lots of snap on cores to keep the RF out of the transceiver, modem
Originally Posted by GrowleyMonster
I am thinking about splitting my backstay into two backstays
, one to the port and one to the starboard quarter, and using the two stays as a inverted vee. Feedpoint of course at the masthead. Maybe even locating the tuner up there, too, right at the feedpoint. Anybody here seen an installation
like that? Not really so far off topic... it would make the problems with RF ground sorta moot.