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Echo-Sensor Installation
Location of the Depth
Sensor
Non-aerated (bubble free)
water must flow across the
transducer face at all
speeds if good depth sound-
ing performance is to be
achieved. The transducer should be located,
where the following conditions can be
met:
1. On sailboats the transducer shoud be
mounted where the acoustic beam will not be
shaded by the keel. A spot forward of a fin
keel is usually best. Try to find an accessible
spot with a minimum dead rise angle.
2. On displacement hull power boats (e.g.
trawlers), the transducer should be mounted
amidships, relatively close to the keel (center-
line of hull).
3. On planing power boat hulls, the trans-
ducer should be mounted well aft and close to
the keel to insure that the transducer is in
contact with the water at higher boat speeds.
If the vessel is capable of speeds greater than
25 knots, you may wish to review installation
location and operational results on similar
boats before proceeding.
4. Never position a depth transducer direct-
ly behind shaft struts, fittings and paddle
wheel speed transducers, since the turbu-
lence can adversely affect depth transducer
performance.
5. On I/O's (stern drive) transducer mount-
ing close to the engine(s) usually yields good
results. On inboards always mount the trans-
ducer well ahead of the propeller(s). Turbu-
lence from props seriously degrades trans-
ducer performance. Make sure transducer is
not shaded by the prop shaft(s).
6. It is very important that the mounting
location have reasonable access from inside
the vessel since the transducer will require
tightening from inside the hull.
7. The transducer transmits also some en-
ergy sideways into the hull. If the returning
echoes from inside the hull are strong enough
to be received, an acoustic isolation between
housing and hull will be required. Any soft
(porous) material may be used.
Flow Direction
Attention:
the fairing must
not be too flat; otherwise the
boundary layer would be deflected
onto the transducer face!
8. At speeds above 10 kts the turbulent
boundary layer will provide a shield for the
transmitted and received signals, preventing
any echo sounder operation. To overcome
this, a fairing of non swelling material should
be fitted, to place the transducer face below
the boundary layer.
Maintaining the Depth
Transducer
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. It is recom-
mended that the external face of the transduc-
er be coated with an antifouling paint. Use
only mineral spirits based antifouling paint. Do
not use Ketone based paints since they attack
the potting materials used in the transducer. If
fouling does occur, use a stiff brush or putty
knife to remove growth. Wet sanding of fouled
transducer face is permissible with NR. 220 or
finer grade type emery paper (use plenty of
water).
37
Fairing
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