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strap or 2 to 3 inch wide 2 mil copper foil. Make sure that the contact point is
free from paint and dirt. Ensure a good contact area for minimum resistance.
Wooden and fiberglass hulled vessels present more of a grounding problem. It
is normally necessary to bond all large metallic parts such as the stove, fuel
tanks, engine, propeller shaft, etc., and sometimes an external grounding
plate should be connected to the hull. The bonding and grounding plate
should take into consideration the problems of electrolysis. Severe damage
may result if dissimilar metals are connected together.
Our experience is that sacrificial zincs, which double as radio grounds, may
help, but are not by themselves a complete solution. If you use one (or more)
of these devices, remember to provide for a large physical counterpoise in
addition.
In a sailboat installation, we generally place the Smartuner in the aft lazarette
and then run at least three runs of foil forward. One runs up the port chine,
just below the waterline, another up the starboard chine below the waterline
and the third up the center of the vessel.
The center foil is generally connected to the rudder post, transmission, engine
and keel bolts. The chine foils are attached to through hulls, the stove, tank-
age and so forth. The idea is to get as much metal inside the vessel connected
as possible. Metal toe rails and life lines work well as do keel coolers on motor-
ized craft.
Here is a tip for attaching foil to keel bolts. When a large keel bolt is exposed,
drill into the keel bolt and tap the hole for a suitable stainless steel machine
screw. Attach with suitable copper washers for a solid electrical connection.
Although it is not mandatory that ground foil be glued into place, we consider
it a good idea to keep the space below decks neat and orderly under all condi-
tions.
If you are using a backstay antenna, try to visualize your ground as you look
down from the top of the mast. Ask yourself if you see 100 square feet of metal
below you. The closer to this figure you can get, the better your radiated sig-
nal will be. What you are trying to do is make a large capacitor to the sea
water. Consider the salt water of the sea to be one plate of a capacitor, the
ground system the other and the hull to be the dielectric.
On marine installations, you should also be very aware of potential noise
sources which may need to be bypassed to ground. We have encountered just
about every source of noise imaginable in vessel installations. When you are
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© 1998 SGC Inc
SG-230 Manual