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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
Preparations, page 22
Where to install the transducer, page 38
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 CP200-5C transducer.
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 on
that side. The cavitation starts when the water flows in the same direction as the propeller
blades. This is where the propeller blades move downwards.
Related topics
Preparations, page 22
Where to install the transducer, page 38
Summary of Contents for Simrad CP200-5C
Page 1: ...Photo by Gatis Marcinkevics kongsberg com simrad Simrad CP200 5C INSTALLATION MANUAL ...
Page 2: ......
Page 55: ...484164 A 53 Related topics Preparations page 22 Acoustic noise page 45 Preparations ...
Page 58: ...56 484164 A Related topics Preparations page 22 Simrad CP200 5C Installation Manual ...
Page 101: ...484164 A 99 Drawing file ...
Page 110: ... 2022 Kongsberg Maritime ...