AIR ECHOES:
Air echoes can be caused by too much turbulence under the face of the transducer. It is important
to know that ultra sonic signals from a transducer will not penetrate air. They react to air in the
same manner as they react to a hard bottom described above. Therefore, if your transducer is not
mounted properly and you are getting turbulence (air bubbles) under your transducer, you may
get false readings simply because signals are being returned by the turbulence and never
reaching the bottom.
Adjusting the Shallow Water sensitivity can reduce this problem. Adjustment of the transducer
location can also help solve these false readings.
TRANSDUCER REPLACEMENT/IDENTIFICATION TAG
On most transducers manufactured after 1987, the operating frequency and part number is
attached to the cable or is printed on a mylar tag near the connector end. Do not remove this tag
since it identifies the transducer and will help you identify the operating frequency of the
transducer. (Improper frequency will cause your instrument to not operate properly.) Removal of
the identification tag will void the warranty.
SALTWATER MAINTENANCE/ANTIFOULING PAINT
Antifouling Paint: If the vessel is kept in saltwater, sea growth can accumulate rapidly on the
transducer face and seriously reduce performance in a matter of weeks. If fouling does occur, use
a stiff brush or putty knife to remove this growth. Wet sanding of the fouled transducer face is
permissible with #220 or finer grade of wet or dry emery paper. (Use plenty of water.) Coating
transducers with antifouling paint is often necessary to achieve consistent performance. All anti
fouling paints have a solvent base and solvents attack encapsulation materials and plastics to
varying degrees. If you need anti fouling protection use only paints with a mineral spirits base; do
not use acetone vinyl based paints. Glouchester (RULE) 7 is a hard, mineral spirits based paint
that we have found to be practically transparent to acoustic energy. Never apply paint to the
transducer by spraying; use a brush or roller. A sprayed surface “wets” very slowly and there are
often microscopic air pockets under the surface which attenuate the sound energy.
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