Defining The Middle Position Of The Transducer - Simrad SN90 Operator's Manual

Simrad SN90 Operator Manual
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Defining settings related to user preferences and individual customizing, page 102

Defining the middle position of the transducer

The hull unit provided with the SN90 is designed to lower the transducer down below
the ship's hull when the SN90 shall be used. When the SN90 is switched off, the
transducer is hoisted for protection. The SN90 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 SN90.
Retracting the transducer to a middle position may be useful if you use the SN90
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.
112
to save your settings.
Apply
dialog box, or select
Installation
to close it.
OK
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