Simrad EC150-3C, Руководство по установке

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438371/A
• The turbulent flow is a disorderly flow pattern, full of eddies.
A Turbulent flow
B Laminar flow
C Air bubbles
Air bubbles absorb and reflect the sound energy, and they may in worst cases block the
sound transmission altogether.
The boundary layer increases in thickness when it becomes turbulent. The boundary
layer is thin in the forward part of the vessel hull, and increases as it moves aft. The
thickness depends on ships speed and on the roughness of the hull. All objects sticking
out from the hull, or dents in the hull, will disturb the flow and will increase the thickness
of the boundary layer. When the flow speed is high, the turbulence can be violent enough
to destroy the integrity of the water. Small voids or cavities in the water will occur and
this is called cavitation.
It is our experience that a wide 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.
Related topics
Where to install the transducer, page 45
Installation summary, page 30
Keep the transducer far away from the propellers
The propulsion propellers is the dominant noise source on most vessels. The noise
is easily transmitted through the water. This noise may often reduce the overall
performance of your EC150-3C.
The transducer must be installed as far away from the propellers as possible. The best
positions are therefore on the fore part of the hull. Positions outside the direct line of
sight from the propellers are best.
On small vessels we recommend mounting the transducer on that side of the keel where
the propeller blades move
upwards . This is because the propeller cavitation is weakest
Simrad EC150-3C Installation Manual