Avoid Protruding Objects Near The Transducer; Mount The Transducer At Forward Part Of Hull To Minimize The Effects From The Flow Boundary Water Layer - Simrad EC150-3C Installation Manual

Preparations
Slamming
Slamming happens if the vessel hull climbs out of the water in heavy seas. The force of
the water when the hull falls down may push the transducer up, and may cause damage
both to the transducer and to its mounting. This is especially important for low frequency
transducers with large faces. The effect of slamming can be reduced by mounting the
transducer as deep as possible on the hull.
Note
Kongsberg Maritime AS takes no responsibility for any damages to the transducer, the
cable or the mounting arrangement, caused by slamming.
Related topics
Where to install the transducer, page 45
Installation summary, page 30

Avoid protruding objects near the transducer

Objects protruding from the hull will generate turbulence and flow noise. This will
reduce the EC150-3C 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. If
necessary, grind and polish all surfaces.
Related topics
Where to install the transducer, page 45
Installation summary, page 30
Mount the transducer at forward part of hull to minimize the
effects from the flow boundary water layer
The upper water layers of the sea contain a myriad of small air bubbles created by the
breaking waves. When the hull moves through water it will cause a disturbance, and this
will generate friction. The friction zone is called the flow boundary layer.
The flow in this boundary layer may be laminar or turbulent.
• The laminar flow is a nicely ordered, parallel movement of the water.
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