Simrad ES200-7C - REV E, Installation Manual

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Where to mount the transducer
and flat bottom, with a rising angle less than around 13 degrees,
is prone to giving air problems for the transducer. In any case a
transducer location in the forward part of the hull is preferred in
order to minimise the influence of the boundary layer.
Mount the transducer far away from the propellers
The propulsion propeller is the dominant noise source on most
fishing vessels, research vessels, merchant vessels and pleasure
crafts. The noise is transmitted through the sea water. For
this reason, the transducer should be placed far away from the
propeller, which means on the fore part of the hull. Positions
outside the direct line of sight from the propeller are favourable.
On small vessels with short distances it is advised to mount the
transducer on that side of the keel where the propeller blades
move upwards, because the propeller cavitation is strongest on
the other side. The cavitation starts most easily when the water
flows in the same direction as the propeller blade, and that is to
some degree the case at that side of the keel where the propeller
blades move downwards.
Mount the transducer far away from the bow
thrusters
Bow thruster propellers are extremely noisy. When in operation,
the noise and cavitation bubbles created by the thruster make
the echo sounder useless, almost no matter where the transducer
is installed. And when not in operation, the tunnel creates
turbulence, and if the vessel is pitching, the tunnel may be filled
with air or aerated water in the upper position and release this in
the lower position. In general, all transducers must be therefore
placed well away from the bow thruster. However, this is not
an invariable rule. Certain thruster designs combined with its
physical location on the hull may still offer suitable transducer
locations near the thruster. If you are in doubt, consult a naval
architect.
Mount the transducer with a slightly inclined
transducer face
Ideally, the transducer face should be mounted in parallel with the
sea surface when the vessel is in normal trim, as this will provide
the most accurate echo information. However, it is also very
important that the water flow over the transducer face is laminar.
In order to ensure laminar flow, the transducer face may be tilted
slightly upwards in relation to the water flow. This allows the
flowing water to meet the face directly, and assures laminar flow.
The inclination angle must however be determined carefully. The
angle must be small on transducers with narrow beam angles. As
a rule of thumb, mount transducers with beam angles smaller
than seven degrees with minimum inclination angle. The smaller
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