Kongsberg EA640, Installation Manual

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413764/B
Where to install the transducer
Topics
Introduction to transducer location, page 20
Mount the transducer deep, page 20
Avoid protruding objects near the transducer, page 21
Keep the transducer far away from the propellers, page 22
Mount the transducer at a safe distance from bow thruster(s), page 22
Summary and general recommendations, page 22
Introduction to transducer location
A single answer to the question "where to install the transducer" cannot be given.
The physical location of the transducer depends on the vessel's design and construction,
how the hull is shaped, and how the water runs along the hull. There are however a
number of important guidelines, and some of these are even conflicting.
Note
The information here must be considered as general advice. Each EA640 installation
must be handled separately depending on the hull design and the other electrical and
mechanical systems installed on the vessel.
Mount the transducer deep
In order to achieve the best possible EA640 performance, mount the transducer as deep
as possible under the vessel’s hull.
There are several reasons for this recommendation.
Flow noise
Consider the situations when the vessel is unloaded, and pitching in heavy seas. The
vessel is riding high, and the bow may even be lifted out of the water. This will cause a
lot of air to follow the shape of the hull.
The upper water layers of the sea contain a myriad of small air bubbles created by the
breaking waves. In heavy seas the upper 5 to 10 metres may be filled with air, and the
highest concentrations will be near the surface. Air bubbles absorb and reflect the sound
energy, and they may in worst cases block the sound transmission altogether.
EA640 Installation Manual