Kongsberg Simrad MF90, Installation Manual

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Defining the middle position of the transducer
The hull unit is used to lower the transducer down below the ship’s hull when the MF90
system shall be used. When the MF90 system is turned off, the transducer is hoisted for
protection. The MF90 system allows you to define a middle position for the transducer.
Prerequisites
The physical properties of the hull unit installation are known.
The correct type of hull unit is selected.
The vessel is berthed or at sea.
Context
The middle position is not a fixed length. The physical middle position depends on which
type of hull unit you are using with the MF90 system.
Retracting the transducer to a middle position may be useful if you use the MF90 system
simultaneously with other sonars. A higher position will permit you to increase the vessel
speed. If you operate in very shallow waters, you may also reduce the risk of hitting bottom.
However, placing the transducer immediately under the hull may increase the flow noise.
Caution
If the transducer hits larger objects or bottom, the transducer shaft may be bent, or - in
worst case - it can be broken off. A broken transducer shaft will cause water leakage
through the top of the shaft. If you suspect that the transducer shaft is seriously damaged
with holes, do not retract the transducer to its upper position.
To prevent serious damage to the vessel or the vessel stability, you must have a water
pump and a warning system in the sonar room.
Select the middle position carefully. The position is normally selected to place the transducer
just under the keel, but low enough to prevent echoes from the trunk. Once the position is
selected, make sure that the system protection functionality does not inhibit transmission.
Procedure
1 Make sure that you have sufficient water depth below
the keel before you lower the transducer.
2 On the top bar, select
Hull Unit
to access the control
settings.
3 Select [
+
] and [
–
] to adjust the middle position.
Setting to work