Avoid Protruding Objects Near The Transducer; Using A Suitable Inclination Angle - Simrad ES38DD Installation Manual

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Simrad ES38DD Installation Manual

Avoid protruding objects near the transducer

Objects protruding from the towed body will generate turbulence and flow noise. This

will reduce the ES38DD performance.

Protruding objects may be zinc anodes, transducers or even the vessel's keel. Holes and

pipe outlets are also important noise sources, as well as rough surfaces caused by bad

welding. Even traces of sealing compound, sharp edges, bolts or empty bolt holes will

create noise. All these protruding objects may act as resonant cavities amplifying the

flow noise at certain frequencies.

Do not place a transducer in the vicinity of protruding objects, and especially not close

behind them. Make sure that the surface of the transducer face, the hull plating and putty

around the transducer is as even and smooth as possible. Mounting screws or bolts must

not be extruding from the transducer, the installation hardware or the hull plating. Even

traces of sealing compound, sharp edges, bolts or empty bolt holes will create noise.If

necessary, grind and polish all surfaces.

Ideally, the transducer face should be mounted in parallel with the sea surface when the

towed body 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 must be tilted slightly

upwards in relation to the water flow. This

allows the flowing water to meet the face

directly, and reduces laminar noise.

The inclination angle must be determined

carefully. The angle must be small on

transducers with a narrow beam angles. As a rule of thumb, mount transducers with

beam angles smaller than seven degrees with 1 ° inclination angle. The smaller beam

angle your transducer has, the smaller the inclination angle can be.

Note

Ensure that you do not mount the transducer with a negative inclination angle. This may

cause turbulence on the transducer face, and reduced ES38DD performance.

341701/B

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