Simrad ES70 - INSTALLATION REV A Installation Manual page 118

Simrad ES70
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 beam angle your transducer has, the smaller the inclination angle can
be. Ensure that you do not mount the transducer with a negative inclination angle. This
may cause turbulence under the transducer face, and reduced echo sounder performance.
Summary and general recommendations
Some of the above guide lines are conflicting, and each case has to be treated individually
in order to find the best compromise. Generally the propeller noise is the dominant factor,
and a recommended transducer location is in the fore part of the hull, with maximum
distance from the bow equal to one third of the total length of the hull at the water line.
Figure 22 General recommendation for transducer location
A Transducer
Inclination angle
B
C Hull length at water line
D Maximum 1/3 of the hull length at water line (C)
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