The Dockyard Electric Advisor
Antenna and Grounding
systems on Pleasure boats.
There are as many ways and ideas of mounting an SSB radio and antenna systems on a pleasure boat, as there are would be experts!A sound advice will always be to look to the Merchant fleet and their way of doing things, and then adapt it to the smaller boat, with the imperfections, that will give.
What I say here will give a lot of experts the shivers; the most efficient antenna will be a whip antenna the longer the better, but with the norm of today a length of 24 feet would be sufficient if the ground plane / counterpoise are of good standing.
Why should a whip be a good choice? The radiation pattern is very flat, non-directive, and thereby it will give good long distance contacts.
First, some facts:
Almost any modern merchant ship uses more or less the same equipment, as will be used on a pleasure boat. The transmitting power will mostly be no more than 250 watts, the antenna system a whip antenna of 24 feet, the antenna coupler / tuner will be the automatic type, where a burst of power will start the tuning process, and do that in seconds!
On the big cargo ship the ground plane will be the whole metal construction of the hull, the tuner / antenna coupler mounted beneath the whip antenna up on monkey island.
With a setup like that, they have contacts with other ships on low frequencies on very long distances, longer than any pleasure boat will ever achieve!
If you have a steel boat or aluminum boat, you will be better off than most, as your hull will act as a very good ground plane.
Where the hull is made from fiberglass or wood, you should mount a grounding plate, an sintered bronze plate or, if you don’t like perforations in your hull, you can put out a layer of copper strips below the waterline inside your hull, and that will work as good as the bronze shoe.
All ground connections should be made with an 2 to 3 “ wide copper strip, and don’t forget to ground your radio too!
But with a bit of care, a little investment and a few hours of work, you can achieve very good results on any boat, whatever type of materiel is used for the hull.
Any solution will have advantages and drawbacks, and of course any system will have to be adapted to the particular boat.
Any of the two antenna systems will work, some boats will have very good results, and then others who have used the same method, will find they have a very inefficient system.
In many cases a trial and error system will have to be used to fine-tune the system, when the original installation is finished.
Mounting the antenna:
A whip antenna must be as free of obstructions as possible, and the antenna tuner must be mounted directly beneath the antenna. Any conducting parts should be insulated to assure, that a hand involuntarily could touch them and thereby get burned.
An insulated backstay:
You will need expert help to take down your backstay and mount the insulators, which will convert your backstay from a normal backstay into an antenna.
Insulators are avaible from varies manufactures and in different forms, therefore contact you rigging specialist.
Mount the upper insulator at least 1 to 2 feet away from the top, and the one at the deck at least 6 feet or more above the deck to prevent any person from getting a burn or an electric chock by touching the antenna when transmitting.
Setting up the Ground system!
As mentioned above a sintered bronze plate, and connecting up any other big metal part in the boat, like stainless steel tanks and so on, and if it’s possible to lay out extra copper strips at the bottom of the boat in conjunction with the bronze plate, the more the better.
It’s not recommended to use the lifelines as a ground! Even I know of some cases, where it actually did work very well!
Use copper strip to connect any of the metal parts to the tuner and the radio, and the shorter the run the better!
The coaxial cables in between Radio and Tuner should always be of a good quality and the heavy RG 8 U or RG 213 would be a good choice.
One should take good care soldering on the connectors, or maybe let the supplier do the installation.
The cable from the tuner to the antenna should always be kept away from any conducting material. If an insulated backstay is the choice of antenna, the cable connecting to the backstay should be at least 2” from the non-insulated part of the stay. Have the supplier make up pieces of plexi glass as spreaders and fasten with wire straps. The same applies if you have to fit the cable to stanchions or a pulpit.
The power to the radio should have cabling of a sufficient dimension, as the consumption of the transmitter can reach up to 20 Amps. Look in this catalog for the right size.
Authors Note:
As I mentioned in the beginning of the writing, there are many ways of doing installations AND there are as many fairytales around of how to do it right.
I don’t claim to be the only one, who knows how to do an installation, on the contrary! But with 23 years of experience onboard a boat, being a Net Controller and Adviser for the last 11 years, and with 6 years in the Caribbean (The Albatros Net), many boats over all these years have given me a world of practical information, which doesn’t always coincide with the theoretical principles of installations of radios and aerial systems, but it works!
Alex F. Larsen S/Y “ALBATROS”